WO1997020362A1 - Virtual network configuration and management system for satellite communications system - Google Patents

Abstract

In a mobile satellite system, a system for providing satellite communication between multiple users in a virtual network arrangement includes first and second mobile earth terminals (METs) responsively connected to and registering with the mobile satellite system. The first MET selects a virtual network identifier (VN ID) representing a virtual network group including the first and second METs to establish voice communication therewith and transmits the VN ID to a central controller. The central controller receives the VN ID from the first MET, validates the first MET for communication, validates the VN ID, allocates a frequency for the virtual network group, and broadcasts the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith. The second MET tunes to the frequency in response to the message broadcast by the central controller.

Description

VIRTUAL NETWORK CONFIGURATION AND MANAGEMENT SYSTEM FOR SATELLITE COMMUNICATIONS SYSTEM

Related Applications

This application claims priority from: U.S.

provisional application serial number 60/007,742 filed on November 30, 1995 entitled "COMMUNICATIONS GROUND SEGMENT SYSTEMS ARCHITECTURE," U.S. application serial no. 08/565,036, filed November 30, 1995, entitled

"FRAUD DETECTION AND USER VALIDATION SYSTEM FOR MOBILE EARTH TERMINAL COMMUNICATION DEVICE," U.S. patent application serial number 08/654,198 filed on May 28, 1996 entitled "COMMUNICATION PROTOCOL FOR MOBILE EARTH TERMINAL COMMUNICATION DEVICE USED IN MOBILE SATELLITE COMMUNICATION SYSTEM," U.S. provisional application serial number 60/007,748 filed on November 30, 1995 entitled "NETWORK OPERATIONS CONTROLLER (NOC)," U.S. patent application serial number 08/700,943 filed on

August 21, 1996 entitled "NETWORK OPERATIONS CONTROLLER FOR MOBILE EARTH TERMINAL SATELLITE COMMUNICATIONS SYSTEM," U.S. provisional application serial number 60/007,749 filed on November 30, 1995 entitled "GROUP CONTROLLER," and U.S. patent application serial number 08/728,227 filed on October 10, 1996 entitled "IMPROVED NETWORK CONTROL CENTER FOR SATELLITE COMMUNICATION SYSTEM," all of which are hereby incorporated by reference. Technical Field

The present invention relates generally to a satellite trunked radio service system for satellite communication, and more particularly, to a virtual network configuration and management system for

satellite communication utilizing a shared satellite demand period circuit associated with private voice networks. Background Art

An overview of the satellite network system is illustrated in Figure 1. The satellite network system design provides the capability for METs and FESs to access one or more multiple beam satellites located in geostationary orbit to obtain communications services.

The heart of the satellite network system for each of the networks is the Network Control System (NCS) which monitors and controls each of the networks. The principal function of the NCS is to manage the overall satellite network system, to manage access to the satellite network system, to assign satellite circuits to meet the requirements of mobile customers and to provide network management and network administrative and call accounting functions.

The satellites each transmit and receive signals to and from METs at L-band frequencies and to and from Network Communications Controllers (NCCs) and

Feederlink Earth Stations (FESs) at Ku-band

frequencies. Communications at L-band frequencies is via a number of satellite beams which together cover the service area. The satellite beams are sufficiently strong to permit voice and data communications using inexpensive mobile terminals and will provide for frequency reuse of the L-band spectrum through interbeam isolation. A single beam generally covers the service area.

The satellite network system provides the

capability for mobile earth terminals to access one or more multiple beam satellites located in geostationary orbit for the purposes of providing mobile

communications services. The satellite network system is desired to provide the following general categories of service:

Mobile Telephone Service (MTS). This service provides point-to-point circuit switched voice connections between mobile and public switched

telephone network (PSTN) subscriber stations. It is possible for calls to be originated by either the mobile terminal or terrestrial user. Mobile terminal-to-mobile terminal calls are also supported.

Mobile Radio Service (MRS). This service provides point-to-point circuit switched connections between mobile terminal subscriber stations and subscriber stations in a private network (PN) which is not a part of the PSTN. It is possible for calls to be originated from either end. Mobile terminal-to-mobile terminal calls are also supported.

Mobile Telephone Cellular Roaming Service (MTCRS). This service provides Mobile Telephone Service to mobile subscribers who are also equipped with cellular radio telephones. When the mobile terminal is within range of the cellular system, calls are serviced by the cellular system. When the mobile terminal is not in range of the cellular system, the MTCRS is selected to handle the call and appears to the user to be a part of the cellular system. When the mobile terminal is not in range of the cellular system, the MTCRS is selected to handle the call and appears to the user to be a part of the cellular system. It is possible for calls to be originated either from the MET or the PSTN Mobile terminal-to-mobile terminal calls are also supported.

Mobile Data Service (MDS). This service provides a packet switched connection between a data terminal equipment (DTE) device at a mobile terminal and a data communications equipment (DCE) /DTE device connected to a public switched packet network. Integrated

voice/data operation is also supported.

The satellites are designed to transmit signals at L-band frequencies in the frequency band 1530-1559 MHz. They will receive L-band frequencies in the frequency band 1631.5 - 1660.5 MHz. Polarization is right hand circular in both bands. The satellites will also transmit in the Ku frequency band, 10,750 MHz to 10,950 MHz, and receive Ku-band signals in the frequency band 13,000 to 13,250 MHz.

The satellite transponders are designed to

translate communications signals accessing the

satellite at Ku-band frequencies to an L-band frequency in a given beam and vice versa. The translation will be such that there is a one-to-one relation between frequency spectrum at Ku-band and frequency spectrum in any beam at L-band. The satellite transponders will be capable of supporting L-band communications in any portion of the 29 MHz allocation in any beam.

Transponder capacity is also provided for Ku-band uplink to Ku-band down-link for signalling and network management purposes between FESs and NCCs. The

aggregate effective isotropic radiated power (AEIRP) is defined as that satellite e.i.r.p. that would result if the total available communications power of the

communications subsystem was applied to the beam that covers that part of the service area. Some of the key performance parameters of the satellite are listed in Figure 2.

The satellite network system interfaces to a number of entities which are required to access it for various purposes. Figure 3 is a context diagram of the

satellite network system illustrating these entities and their respective interfaces. Three major classes of entities are defined as user of communications services, external organizations requiring

coordination, and network management system.

The users of satellite network communications services are MET users who access the satellite network system either via terrestrial networks (PSTN, PSDN, or Private Networks) or via METs for the purpose of using the services provided by the system. FES Owner/Operators are those organizations which own and control FESs that provide a terrestrial interface to the satellite network. When an FES becomes a part of the satellite network, it must meet specified technical performance criteria and interact with and accept real-time control from the NCCs. FES Owner/Operators determine the customized services that are offered and are ultimately responsible for the operation and maintenance of the FES. Customers and service

providers interact with the Customer Management

Information System within the Network Management

System.

The satellite network system interfaces to, and performs transactions with, the external organizations described below:

Satellite Operations Center (SOC): The SOC is not included in the satellite network ground segment design. However, the satellite network system

interfaces with the SOC in order to maintain cognizance of the availability of satellite resources (e.g. in the event of satellite health problems, eclipse operations, etc.) and, from time to time, to arrange for any necessary satellite reconfiguration to meet changes in traffic requirements.

NOC : The satellite network system interfaces with the satellites located therein via the NOC for a variety of operational reasons including message delivery and coordination.

Independent NOCs: The satellite network system interfaces with outside organizations which lease resources on satellite network satellites and which are responsible for managing and allocating these resources in a manner suited to their own needs.

Other System NOCs : This external entity represents outside organizations which do not lease resources on satellite network satellites but with whom operational coordination is required.

The satellite network management system (NMS) is normally located at an administration's headquarters and may comprise three major functional entities;

Customer Management Information System (CMIS), Network Engineering, and System Engineering (NE/SE). These entities perform functions necessary for the management and maintenance of the satellite network system which are closely tied to the way the administration intends to do business. The basic functions which are

performed by CMIS, Network Engineering, and System Engineering are as follows:

Customer Management Information System: This entity provides customers and service providers with

assistance and information including problem

resolution, service changes, and billing/usage data. Customers include individual MET owners and fleet managers of larger corporate customers. Service providers are the retailers and maintenance

organizations which interact face to face with

individual and corporate customers.

Network Engineering: This entity develops plans and performs analysis in support of the system.

Network Engineering analyzes the requirements of the network. It reconciles expected traffic loads with the capability and availability of space and ground

resources to produce frequency plans for the different beams within the system. In addition, Network

Engineering defines contingency plans for failure situations.

System Engineering: This entity engineers the subsystems, equipment and software which is needed to expand capacity to meet increases in traffic demands and to provide new features and services which become marketable to subscribers. The satellite network system comprises a number of system elements and their interconnecting

communications links as illustrated in Figure 4. The system elements are the NOC, the NCC, the FES, the MET, the Remote Monitor Station (RMS), and the System Test Station (STS). The interconnecting communications links are the satellite network Internetwork,

terrestrial links, the MET signaling channels, the Interstation signaling channels, and the MET-FES communications channels. The major functions of each of the system elements are as follows:

NOC. The NOC manages and controls the resources of the satellite network system and carries out the administrative functions associated with the management of the total satellite network system. The NOC

communicates with the various internal and external entities via a local area network (LAN) /wide area network (WAN) based satellite network Internetwork and dial-up lines.

NCC. The NCC manages the real time allocation of circuits between METs and FESs for the purposes of supporting communications. The available circuits are held in circuit pools managed by Group Controllers (GCs) within the NCC. The NCC communicates with the NOC via the satellite network Internetwork, with FESs via Ku-to-Ku band interstation signaling channels or terrestrial links, and with mobile terminals via Ku-to-L band signaling channels.

FES. The FES supports communications links between METs, the PSTN, private networks, and other MTs. Once a channel is established with an MET, call completion and service feature management is accomplished via In-Band signaling over the communication channel. Two types of FESs have been defined for the satellite network system; Gateway FESs and Base FESs. Gateway FESs provide MTS, MRS, MTCRS and NR services. Base FESs are for like services and/or value added services.

MET. The MET provides the mobile user access to the communications channels and services provided by the satellite network system. A range of terminal types has been defined for the satellite network system.

RMS. The RMS monitors L-band RF spectrum and transmission performance in specific L-band beams. An RMS is nominally located in each L-band beam. Each RMS interfaces with the NOC via either a satellite or terrestrial link.

STS. The STS provides an L-band network access capability to support FES commissioning tests and network service diagnostic tests. The STS is

collocated with, and interfaced to, the NOC.

Communications channels transport voice, data and facsimile transmissions between METs and FESs via the satellite. Connectivity for MET-to-MET calls is accomplished by double hopping the communications channels via equipped FESs. Signaling channels are used to set up and tear down communications circuits, to monitor and control FES and MET operation, and to transport other necessary information between network elements for the operation of satellite network. The system provides Out-of-Band and Interstation signaling channels for establishing calls and transferring information. In-Band signaling is provided on

established communications channels for supervisory and feature activation purposes. A detailed description of the satellite network signaling system architecture is provided in L. White, et al., "North American Mobile Satellite System Signaling Architecture," AIAA 14th International Communications Satellite Conference, Washington, DC (March 1992), incorporated herein by reference. The satellite network Internetwork provides

interconnection among the major satellite network ground system elements such as the NOCs, NCCs, and Data Hubs, as well as external entities. Various leased and dial-up lines are used for specific applications within the satellite network system such as backup

interstation links between the NCC and FESs and

interconnection of RMSs with the NOC.

The primary function of the NOC is to manage and control the resources of the satellite network system. Figure 5 is a basic block diagram of the NOC and its interface. The NOC computer is shown with network connections, peripheral disks, fault tolerant features, and expansion capabilities to accommodate future growth. The NOC software is represented as two major layers, a functional layer and a support layer. The functional layer represents the application specific portion of the NOC software. The support layer

represents software subsystems which provide a general class of services and are used by the subsystems in the functional layer.

The application specific functions performed by the NOC are organized according to five categories: fault management, accounting management, configuration management, performance management, and security management. The general NCC Terminal Equipment (NCCTE) configuration showing constituent equipment includes: processing equipment, communications equipment, mass storage equipment, man-machine interface equipment, and optional secure MET Access Security Key (ASK) storage equipment. The Processing Equipment consists of one or more digital processors that provide overall NCC control, NCS call processing, network access processing and internetwork communications processing.

The Communications Equipment consists of satellite signaling and communications channel units and FES terrestrial communication link interface units. The Mass Storage Equipment provides NCC network

configuration database storage, call record spool buffering an executable program storage. The Man-Machine Interface Equipment provides operator command, display and hard copy facilities, and operator access to the computer operating systems. The MET ASK storage Equipment provides a physically secure facility for protecting and distributing MET Access Security Keys.

The NCCTE comprises three functional subsystems:

NCCTE Common Equipment Subsystem, Group Controller Subsystem, and Network Access Subsystem. The NCCTE Common Equipment subsystem comprises an NCC Controller, NCCTE mass storage facilities, and the NCCTE man-machine interface. The NCC Controller consists of processing and database resources which perform

functions which are common to multiple Group

Controllers. These functions include satellite network Internetwork communications, central control and monitoring of the NCCTE and NCCRE, storage of the network configuration, buffering of FES and Group

Controller call accounting data, transfer of

transaction information to the Off-line NCC and control and monitoring of FESs.

The Mass Storage element provides NCC network configuration database storage, call accounting data spool buffering, and NCCTE executable program storage. The Man-machine Interface provides Operator command and display facilities for control and monitoring of NCC operation and includes hard copy facilities for logging events and alarms. A Group Controller (GC) is the physical NCC entity consisting of hardware and software processing resources that provides real time control according to the CG database received from the NOC.

The Group Controller Subsystem may incorporate one to four Group Controllers. Each Group Controller maintains state machines for every call in progress within the Control Group. It allocates and deallocates circuits for FES-MET calls within each beam of the system, manages virtual network call processing, MET authentication, and provides certain elements of call accounting. When required, it provides satellite bandwidth resources to the NOC for AMS (R) S resource provisioning. The Group Controller monitors the performance of call processing and satellite circuit pool utilization. It also performs MET management, commissioning and periodic performance verification testing .

The Network Access Subsystem consists of satellite interface channel equipment for Out-of-Band signaling and Interstation Signaling which are used to respond to MET and FES requests for communications services. The Network Access Processor also includes MET

communications interfaces that are used to perform MET commission testing. In addition, the subsystem

includes terrestrial data link equipment for selected FES Interstation Signaling.

The principal function of the FES is to provide the required circuit switched connections between the satellite radio channels, which provide communications links to the mobile earth terminals, and either the PSTN or PN. FESs will be configured as Gateway

Stations (GS) to provide MTS and MTCRS services or Base Stations to provide MRS services (described in detail below). Gateway and Base functions can be combined in a single station.

The FES operates under the real time control of the Network Communications Controller (NCC) to implement the call set-up and take-down procedures of the

communications channels to and from the METs. Control of the FES by the NCC is provided via the interstation signaling channels. An FES will support multiple Control Groups and Virtual Networks. The FES is partitioned into two major functional blocks, the FES RF Equipment (FES-RE) and the FES Terminal Equipment (FES-TE). The principal function of the FES-RE is to provide the radio transmission functions for the FES. In the transmit direction it combines all signals from the communications and interstation signaling channel unit outputs from the FES-TE, and amplifies them and up-convert these to Ku-Band for transmission to the satellite via the antenna. In the receive direction, signals received from the satellite are down-converted from Ku-Band, amplified and distributed to the channel units within the FES-TE. Additional functions include satellite induced Doppler correction, satellite

tracking and uplink power control to combat rain fades.

The principal function of the FES-TE is to perform the basic call processing functions for the FES and to connect the METs to the appropriate PSTN or PN port. Under control of the NCC, the FES assigns

communications channel units to handle calls initiated by MET or PSTN subscribers. The FES-TE also performs alarm reporting, call detail record recording, and provision of operator interfaces.

For operational convenience, an FES may in some cases be collocated with the NCC. In this event, the NCC RF Equipment will be shared by the two system elements and the interstation signaling may be via a LAN. Connection to and from the PSTN is via standard North American interconnect types as negotiated with the organization providing PSTN interconnection. This will typically be a primary rate digital interconnect . Connection to and from private networks is via standard North American interconnect types as negotiated with the organization requesting satellite network service. This will typically be a primary rate digital

interconnect for larger FESs or an analog interconnect for FESs equipped with only a limited number of

channels may be employed.

It has been discovered that there is a general need for an integrated mobile telephone that can be used to transmit to, and receive from, to communicate in a virtual network arrangement that allows each member of the group to hear what any other user is saying. Each member of the group can also talk when needed. The system behaves like a radio multi-party line where several parties communicate over the same communication channel . Public services and law enforcement agencies are typical users of this service, which is normally provided by either traditional terrestrial radio networks or by the more recent trunked radio systems. These trunked systems, generally in the 800-900 MHz band, provide groups of end users with virtual network systems by assigning frequencies on a demand basis. In this connection, however, it has been discovered that an integrated mobile communication device is needed that provides this ability to communicate in a virtual network of a satellite communications system.

It has also been discovered the need for a

nationwide and regional point -to-multipoint mobile communication service that is not limited in coverage. Summary of the Invention

It is a feature and advantage of the present invention to provide an integrated mobile telephone that can be used to transmit and receive in a virtual network arrangement that allows each member of the group to hear what any other user is saying.

It is another feature and advantage of the present invention to permit each member of the group to talk when needed, and to provide a system that behaves like a radio multi-party line. It is a further feature and advantage of the present invention to provide an integrated mobile communication device that can communicate in a virtual network of a satellite network.

It is another feature and advantage of the present invention to provide an inexpensive virtual network satellite service to the owner of the group.

It is another feature and advantage of the present invention to minimize the call set-up time for one shared circuit per virtual network.

It is another feature and advantage of the present invention to generally effectively and efficiently effectuate transmissions between mobile communication devices and the satellite network in a virtual network environment by utilizing an efficient communication protocol .

It is another feature and advantage of the

invention to provide a nationwide and regional point to-multipoint mobile communication service that is not limited in coverage.

The present invention is based, in part, on the desirability of providing point-to-multipoint circuit switched connections between mobile terminal subscriber stations and a central base station in a virtual network. Mobile users are able to listen to two-way conversations and to transmit.

To achieve these and other features and advantages of the present invention, a mobile communication system is provided in a mobile satellite system. The mobile satellite system includes a satellite communication switching office having a satellite antenna for

receiving/transmitting a satellite message via a satellite from/to a vehicle using a mobile

communication system, a satellite interface system, a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the vehicle via the satellite and the satellite interface system. The mobile

communication system includes a user interface system providing a user interface through which a user has access to services supported by the mobile satellite system, and an antenna system providing an interface between the mobile communication system and the mobile satellite system via the satellite interface system, and receiving a first satellite message from the satellite and transmitting a second satellite message to the satellite. The antenna system includes an antenna including one of a directional and an

omnidirectional configuration, a diplexer, an

amplifier, a low noise amplifier, a beam steering unit when the antenna is of the directional configuration, and at least one of a compass and sensor to determine vehicle orientation. The mobile communication system also includes a transceiver system, operatively

connected to the antenna system, including a receiver and a transmitter. The transmitter converts the second satellite message including at least one of voice, data, fax and signaling signals into a modulated signal, and transmits the modulated signal to the antenna system. The transmitter includes an amplifier, a first converter and associated first frequency synthesizer, a modulator, an encoder, multiplexer, scrambler and frame formatter for at least one of voice, fax, and data. The receiver accepts the first satellite message from the antenna system and converts the first satellite message into at least one of voice, data, fax and signaling signals, at least one of the voice, data and fax signals routed to the user

interface system. The receiver includes a second converter with an associated second frequency

synthesizer, a demodulator, a decoder, demultiplexer, descrambler and frame unformatter for at least one of voice, fax, and data. The mobile communication system also includes a logic and signaling system, operatively connected to the transceiver, controlling

initialization of the mobile communication system, obtaining an assigned outbound signaling channel from which updated system information and commands and messages are received. The logic and signaling system configures the transceiver for reception and

transmission of at least one of voice, data, fax and signaling messages, and controls protocols between the mobile communication system and the mobile satellite system, and validating a received signalling messages and generating codes for a signaling message to be transmitted .

In one embodiment of the invention, a system for providing satellite communication between multiple users in a virtual network arrangement includes first and second mobile earth terminals (METs) responsively connected to and registering with the mobile satellite system. The first MET selects a virtual network identifier (VN ID) representing a virtual network group including the first and second METs to establish voice communication therewith and transmits the VN ID to a central controller. The central controller receives the VN ID from the first MET, allocates a frequency for the virtual network group, and broadcasts the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith. The second MET tunes to the frequency in response to the message broadcast by the central controller .

In another embodiment of the invention, a method of providing satellite communication between multiple users in a virtual network arrangement includes the steps of first and second mobile earth terminals (METs) registering with the mobile satellite system, the first MET selecting a virtual network identifier (VN ID) representing a virtual network group including the first and second METs to establish voice communication therewith. The method also includes the steps of the first MET transmitting the VN ID to the central

controller, the central controller receiving the VN ID, allocating a frequency for the virtual network group, and broadcasting the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith. The method also includes the steps of the second MET tuning to the frequency in response to the message broadcast by the central controller.

In another embodiment of the invention, the method also includes the steps of a third MET included in the virtual network group registering with the mobile satellite system, and the central controller

broadcasting the message to the virtual network group including the third MET informing the virtual network group of the allocated frequency and the voice

communication associated therewith The method also includes the steps of the third MET tuning to the frequency in response to the message broadcast by the central controller.

According to the invention, the central controller advantageously controls the virtual network satellite communication including virtual network parameters used by the first and second METs.

The central controller advantageously collects billing information regarding the virtual network satellite communication and transmits the billing information to the mobile satellite system. The mobile satellite system optionally charges a service fee to a customer that has requested the virtual network arrangement instead of each of the individual users in the virtual network group thereby consolidating the billing transactions and permitting a single customer to monitor communication charges.

In another embodiment of the invention, the method includes the steps of the first MET selecting the virtual network identifier (VN ID) representing a virtual network group including the first MET and a non-MET serviced by one of a public switched telephone network and a cellular network to establish voice communication therewith, and the first MET transmitting the VN ID to the central controller. Additionally, the method includes the central controller receiving the VN ID, determining that the virtual network group includes the non-MET, and broadcasting a non-MET message to either the public switched telephone network or the cellular network including the voice communication associated therewith, and either the public switched telephone network or the cellular network receiving the non-MET message from the central controller and

transmitting the non-MET message to the non-MET to establish the virtual network arrangement between the MET and the non-MET.

In another embodiment of the invention, the NOC manages and controls the resources of the satellite network system and carries out the administrative functions associated with the management of the total satellite network system. The NOC communicates with the various internal and external entities via a local area network (LAN) /wide area network (WAN) based satellite network Internetwork and dial-up lines.

The NOCs network management functions include measuring the usage of resources by customers to enable predictions of what changes to make in the future deployment of resources. Such resources may be network elements and CPUs in the system. Data such as usage records are collected and analysis of capacity planning is performed based on present characteristics.

Security functions are provided wherein the network is protected against unauthorized use. Security

mechanisms built in to the network management include enhanced fraud security coding encryption and user passwords. Configuration management, i.e., how

resources are allocated, is another function of the NOC. Fault detection and management are provided for by the NOC. Problems are isolated and reported to operations personnel who can react to the problems.

In another embodiment of the invention, a method of performing a call setup procedure in a mobile satellite system from a call initiated by a mobile communication system (MCS) to a destination served by a public switched telephone network, includes the steps of initiating the call by the MCS, the MCS formatting and transmitting an access request message via a random access channel, and receiving by the central controller the access request message, and transmitting frequency assignments to the MCS and to the SCSO. The method also includes receiving by the MCS the frequency assignment, transmitting a scrambling vector message to the SCSO, and verifying by the SCSO the identity of the MET responsive to the scrambling vector. Upon

successful verification, the method includes the steps of switching by the SCSO and the MCS from call setup mode to voice mode, transmitting by the SCSO voices frames to the MCS including a voice activation disable signal to disable a voice activation timer in the MCS for at least 3 super frames, and transmitting a

destination number to the PSTN. The method also includes the steps of transmitting by the SCSO an enable signal to the MCS to re-enable the call

activation timer in the MCS, and establishing voice communication between the PSTN and the MCS. In another embodiment of the invention, a method of performing a call setup procedure in a mobile satellite system from a call initiated by a destination served by a public switched telephone network (PSTN) to a mobile communication system (MCS) . The method includes the steps of receiving by the SCSO a call from the

destination served by the PSTN, transmitting by the SCSO to the central controller a channel request using interstation signaling, determining by the central controller an identity of the MCS responsive to the destination number, and transmitting a call

announcement via a random access channel. The method also includes the steps of acknowledging by the MCS the call announcement via the random access channel to the central controller, transmitting frequency assignments to the MCS via the random access channel and to the SCSO via an interstation signaling channel, and

transmitting an access security check field used to verify the MCS 's identity. The method also includes the steps of receiving by the MCS the frequency

assignment, and transmitting a scrambling vector message to the SCSO, verifying by the SCSO the identity of the MET responsive to the scrambling vector, and upon successful verification, transmitting by the SCSO a ring command to the MCS. The method also includes the steps of receiving by the MCS of the ring command, generating a ringing signal to a MET user, and

transmitting a ring command acknowledgement to the SCSO. The method also includes the steps of receiving by the SCSO the ring command acknowledgement from the MCS, and once the call setup is complete, transmitting by the MCS voice frames to the SCSO including a voice activation disable signal to disable a voice activation timer in the MCS for at least 3 super frames. The method further includes the steps of upon detection of the MCS switching to a voice frame mode, switching by the SCSO to the voice mode, and transmitting a voice activation enable signal to the MCS to re-enable the call activation timer in the MCS, and establishing voice communication between the PSTN and the MCS.

These, together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully herein described and claimed, with reference being had to the accompanying drawings forming a part hereof wherein like numerals refer to like elements

throughout .

Brief Description of the Drawings

Fig. 1 is a diagram illustrating an overview of the satellite network system;

Fig. 2 is a diagram illustrating key performance parameters of the satellite used in the satellite network system;

Fig. 3 is a diagram of the satellite network system illustrating components and respective interfaces;

Fig. 4 is a diagram of a satellite network system illustrating a number of system elements and their interconnecting communications links;

Fig. 5 is a basic block diagram of the NOC and its interfaces;

Fig. 6 is a basic block diagram of the physical architecture of the mobile earth terminal;

Fig. 7 is a basic block diagram of the functions of the mobile earth terminal;

Figs. 8a-8b are diagrams of the improved call setup protocol used to establish a MET originated voice call;

Figs. 9a-9b are diagrams of the improved protocol used for PSTN originated calls;

Fig. 10 is a block diagram of an improved NOC functional architecture; Figs. 11A - 11C are diagrams of the NOC

architecture in more detail;

Fig. 12 is a basic block diagram of the basic components of the NCC showing the included GC;

Fig. 13 is a diagram of the NCC logical

architecture;

Fig. 14 is a basic block diagram of a circuit switched NAP;

Fig. 15 is a block diagram showing the channel unit (CU) architecture;

Fig. 16 shows the GC subsystems which manage a call in progress;

Fig. 17 is an illustration of the basic role of the GWS within the Mobile Satellite Services (MSS) system;

Fig. 18 depicts the basic call processing

interaction between the GWS and other elements within and outside of the overall MSS system;

Fig. 19 is a functional illustration of the Gateway Switch;

Fig. 20 is an illustration of a virtual network associated with a group of FESs and METs,

Fig. 21 illustrates the basic concept and elements involved in establishment of communications and control in the virtual network system;

Fig. 22 illustrates an example of a virtual network service subscribing organization with several

communication virtual networks;

Fig. 23 is a decision tree of the order of

application of the virtual network rules; and

Fig. 24 is a more detailed illustration of the NCC terminal equipment.

Best Mode for Carrying Out the Invention

The present invention provides point-to-multipoint circuit switched connections between mobile terminal subscriber stations and a central base station. Mobile users are able to listen to two-way conversations and to transmit.

The MET includes all of the communication and control functions necessary to support communications from a vehicle or fixed remote site using the resources of the satellite network system. Figs. 6 and 7 are basic block diagrams of the physical architecture and functions of the mobile earth terminal. The basic functional diagram of Fig. 7 is implemented by baseband processing and RF electronics of Fig. 6. A standard voice coder/decoder receives coded messages from the baseband processing and RF electronic system and decodes the message received from the satellite antenna unit for delivery to the interface unit that includes standard user interfaces. Baseband processing and RF electronics receive satellite communications responsive with low noise amplifier (LNA) and output signals for transmission using the diplexer of the antenna unit . Baseband processing and RF electronics also outputs signals for use with beam steering antennas as will be discussed blow. Advantageously, the mobile earth terminal is functional with antennas that are either steerable or nonsteerable.

The functional subsystems comprising the MET are shown in Fig. 7 and include the user interface,

transceiver, antenna, logic and signaling, power supply subsystems, and Position Determination subsystem. The baseline MET will have a low gain directional antenna in the antenna subsystem. The satellite network system supports communications with METs using omnidirectional and higher gain directional antennas.

The user interface subsystem provides the user interfaces through which the user has access to the services supported by the satellite network system. Depending on the service(s) the MET will be equipped with one or more of the devices or ports. The transceiver subsystem consists of a receiver and a transmitter. The transmitter accepts voice, data, fax and signaling signals and converts them to a modulated RF signal. The transmit RF signal is routed to the antenna subsystem. The transmitter typically consists of the high power amplifier (HPA), the upconverter with its associated frequency synthesizer, the modulators and the modules for voice, Fax, or data encoding, multiplexing, scrambling, FEC encoding, interleaving and frame formatting.

The receiver accepts modulated RF signals from the antenna subsystem and converts them into voice, data, fax or signaling signals as appropriate. The voice, data and fax signals are routed to the user interface subsystem. The receiver typically consists of the downconverter with its associated frequency

synthesizer, the demodulator, and the modules for frame de- formatting, de-interleaving, FEC decoding,

descrambling, demultiplexing and voice, Fax, or data decoding. The transceiver communicates over one channel in each direction at any one time. Thus, the transceiver subsystem will typically consist of only one receiver and one transmitter. However, the MET may also incorporate a pilot receiver for antennas and frequency tracking purposes, or a complete receiver dedicated to the continuous reception of the signaling channel from the Group Controller.

The antenna subsystem provides the MET interface to the satellite network and is responsible for receiving the RF signal from the satellite and transmitting the RF signal generated by the MET towards the satellite. The subsystem typically includes an antenna which may be either directional or omnidirectional, a diplexer, a low noise amplifier (LNA), an optional beam steering unit (BSU) if a directional antenna is used, a device such as a compass or an inertial sensor for the determination of the orientation of the vehicle, and an antenna for the position determination receiver.

The logic and signaling subsystem acts as the central controller for the MET. Its basic functions are to initialize the MET by performing a self test at power up and control, based on a resident system table, the acquisition of one of the METs assigned outbound signaling channels from which updated system

information and commands and messages from the GC are derived. The logic and signaling subsystem sets up and configures the transceiver for the reception and transmission of voice, data, fax or signaling messages as appropriate. The logic and signaling subsystem also handles the protocols between the MET and the FES and between the MET the GC via signaling messages, and checks the validity of the received signaling messages (Cyclic Redundance Check (CRC)) and generates the CRC codes for the signaling message transmitted by the MET.

The logic and signaling subsystem also interprets the commands received from the local user via the user interface subsystem (e.g. on/off hook, dialled numbers, etc.) and take the appropriate actions needed, and generates, or commands the generation, of control signals, messages and indications to the user through the user interface subsystem. The logic signaling system also controls the beam steering unit (if any) in the antenna subsystem, and monitors and tests all the other subsystems. In case of fault detection, it informs the user about the failure and take the

appropriate measures needed to prevent harmful

interference to the satellite network or other systems.

The power supply subsystem provides power to all other subsystems. The external voltage source to which this subsystem interfaces depends on the type of vehicle on which the MET is mounted (e.g. 12/24 Volts DC for land vehicles). A standard receiver such as a GPS or a Loran-C receiver is also provided for the determination of the position of the vehicle. This information is used by the logic and signaling subsystem for beam steering (if used) or for applications such as position reporting. The position determination system is implemented externally to the MET and interfaced through a

dedicated data port in the user interface subsystem.

The function of the Remote Monitor System is to continuously monitor the activity on each GC-S channel and to monitor the activity within the downlink L-band spectrum in the beam in which it is located. An RMS will be located in every beam carrying satellite network traffic. An RMS may be a stand alone station or collocated with the NCC or an FES. The RMS is controlled by the NOC and communicates via leased lines or the interstation signaling channels if collocated with an FES. The RMS detects anomalous conditions such as loss of signal, loss of frame sync, excessive BER, etc. on the GC-S channels and generates alarm reports which are transmitted to the NOC via the leased line interface. In addition, it monitors BER on any channel and power and frequency in any band as instructed by the NOC.

The primary functions of the System Test Stations

(STS) is to provide commission testing capability for every channel unit in a FES and to provide readiness testing for the Off -Line NCC. The STS is collocated with and controlled by the NOC and will comprise one or more specifically instrumented METs. The STS provides a PSTN dial-up port for making terrestrial connections to FESs to perform MET to terrestrial end-to-end testing. The STS also provides a LAN interconnection to the NOC to provide access to operator consoles and peripheral equipment. The MSS signaling system provides the

communications capability between network elements required to set up and release communications circuits, provide additional enhanced services, and support certain network management functions. The network elements discussed above include group controllers (GCs), feederlink earth stations (FESs), and mobile earth terminals (METs). The seven different channel types are:

The basic element of communication for signaling and control for the MSS signaling system is the

Signaling Unit (SU). The SU consists of 96 bits organized in 12 octets of 8 bits each. The first 80 bits comprise the message, and the last 16 a parity check, computed using the CCITT CRC-16 algorithm. For transmission, the SU is convolutionally encoded at either rate 3/4 or 1/2, adding an additional 32 or 96 bits respectively.

The various fields are as follows:

* Message type: A 7 bit code which identifies the meaning of the SU; in this case a request for access to the MSS system for call placement.

* MET-GC Signaling Protocol (MGSP) Header: A 8 bit field comprised of several sub-fields giving particular information related to the protocol: message type (command, response, message), message reference identification, and the number of times the message has been retransmitted.

* RTIN: Reverse Terminal Identification Number - the MET's Electronic Serial Number, by which it

identifies itself in transmissions on the MET-SR channel.

* Digits 1-10: The first 10 digits of the addressed telephone number in the PSTN or private network, in hexadecimal. If the 10th digit is set to "C", an address of greater than 10 digits is indicated.

* CRC: The 16-bit error detection code (Cyclic

Redundancy Code).

The frame formats used in the GC-S, MET-SR and MET-ST channels are closely related, and are based on a common 360 millisecond superframe established on the GC-S channel. All timing relationships in the MSS system signaling scheme are determined from the GC-S frame structure. The GC-S is operated in the QPSK mode at an aggregate rate of 6750 b/s. The stream is divided into superframes of 360 ms, comprising three 120 ms frames. Each frame is in turn comprised of a 24-bit unique word (UW), six SUs, eight flush bits and 10 unused bits, for a total of 810 bits and 120 ms . The first frame of a superframe is identified by inversion of the UW. Mobile terminals throughout the area covered by any beam receive GC-S channels with a total uncertainty of approximately 32 ms, primarily due to their

geographical locations. The received superframe boundary establishes the four 90 ms "slots" in the MET-SR random access channels, which operate in the BPSK mode at 3375 b/s. The actual random access burst is comprised of a 24-bit preamble, a 32-bit UW, a 128-bit SU (96 bits rate 3/4 coded), and eight flush bits, for a total of 192 bits in 56.9 ms. This allows a 33.1 ms guard time between bursts. Mobile Terminals select a MET-SR channel and slot at random from among the permitted choices.

The MET-ST TDMA channels, which also operate in the BPSK mode at 3375 b/s, are comprised of bursts which are equal in length to the GC-S frame, and which are also timed on the received frame boundary. The TDMA burst is made up of a 24-bit preamble, a 32-bit UW, a 192-bit SU (96 bits rate 1/2 coded), and eight flush bits. The total length of the TDMA burst is 256 bits in 75.9 ms, which allows a guard time of 44.1 ms .

Mobile Terminals always respond to commands received on the GC-S on a MET-ST channel which corresponds in number to the position of the command SU in the TDM frame. For example, the MET will respond to a command in SU slot 2 on MET-ST channel 2, and so forth. The response is always transmitted in the second frame time after receipt of the command, so that there is a minimum of 120 ms in which the MET can prepare its response.

The initial phase of establishing a call is handled by out-of-band signaling on the GC-S, MET-SR and MET-ST channels. This phase culminates in assignment of a pair of communication channels to the MET and FES.

When these elements receive and tune to the

communication channels, further signaling and control functions are accomplished using inband signaling. The communication channels, FES-C and MET-C, use a variety of related TDM formats which are determined by the intended use of the link, i.e., voice, data, or

facsimile and one of three possible primary modes:

call setup (entirely signaling), communication (no signaling), or in-band signaling (an occasional

subframe of 128 bits is used for signaling/control).

The same 96-bit SU described above is used to accomplish in-band signaling. The outbound TDM, inbound TDMA, and inbound random access channels provide signaling between the GC and each of the METS in the associated control group. All communications on these channels will be passed in the form of 96 bit (12 octet) messages known as signaling units. Each

signaling unit will begin with a 1-octet messages type field and end with a two-octet cyclic redundancy check. The MET to GC Signaling Protocol (MGSP) serves as the layer two protocol for these channels.

Communications from the group controller (GC) to the mobile terminals is provided by the Outbound TDM or GC-S channel. The primary function of this channel is to carry frequency assignments from the GC to

individual METs. In addition, the Outbound TDM channel carries network status information which is received by all METs in a particular beam and control group. The outbound TDM channel operates at a rate of 6750 bits/s with rate 3/4 FEC. QPSK modulation and nominally 6.5 kHz channel spacing (other spacings are under

investigation) is employed. These parameters are identical to those of the communications channel and were chosen to reduce MET complexity.

Inbound TDMA (MET-ST) channels are used by the MET to respond to actions initiated by the GC, such as responding to the call announcement issued by the GC to check a MET's availability to receive a PSTN originated or MET to MET call. The Inbound Random Access (MET-SR) channels are used by METs to request frequency assignments and for other MET initiated actions. The inbound random access and TDMA channels each operate at a rate of 2400 bits/s with rate 3/4 FEC. DPS modulation and nominally 7.5 kHz channel spacing is employed. This modulation scheme has been selected because of its robust performance in the presence of frequency offset and timing errors. It also exhibits superior performance relative to

conventional BPSK in the presence of band-limiting and hard-limiting.

Each control group has associated with it a number of L-band beams over which it operates. In each of these L-band beams a control group has associated with it a distinct set of outbound TDM, inbound TDMA, and inbound random access channels. The number of

signaling channels of each type in each set is

determined based on the level of signaling traffic flowing between the GC and the METs in that control group in that L-band beam. As signaling traffic levels change, new signaling channels of each type are

allocated to or deallocated from a particular set of channels. The frequencies used for outbound TDM, inbound TDMA, and inbound random access channels are included in the status information carrier in the bulletin board signaling units transmitted on the outbound TDM channel .

Each MET is assigned to one of the outbound TDM channels in the control group and beam to which it belongs. Each control group supports up to 16 outbound TDM channels in each beam. Each outbound TDM channel has associated with it up to 6 inbound TDMA channels. An inbound TDMA channel will only carry messages that are responses to messages received on the outbound TDM channel with which it is associated inbound random access channels will not associated with a particular outbound TDM channel. A MET chooses a inbound random access channel at random from among those associated with its control group and beam each time a message is to be transmitted. Each control group can support up to 64 inbound random access channels in each beam. Up to 64 of these channels may be used system wide to meet the signaling requirements of a fully loaded system supporting 5000 circuits.

Inband signaling channels (FES-C and MET-C) are provided between the FES and the MET. These channels are used to provide signaling for call setup and call release, and also provide the capability to pass other signaling information while a call is in progress. The FES-C and MET-C channels are operated in two separate modes in "call setup mode" only signaling messages are carried by the channel. In voice mode voice frames are carried by the channel, but the capability to inject signaling messages by occasionally dropping voice subframes exists. Frames containing inband signaling messages employ a unique word different from that used for frames containing only voice subframes.

Interstation signaling channels (GC-I and FES-I) are used to pass signaling information between the GC and each of the FESs. These channels operate at a rate of 9.6 to 64 kbit/s and are implemented using either the available 5 MHz Ku-band satellite capacity or terrestrial links. The LAP-F protocol will be employed on those links to ensure reliable transfer of variable length signaling and network management messages.

When a MET is idle (powered on and ready to receive a call) it will continuously receive an Outbound TDM channel in order to receive call announcements

associated with incoming calls and obtain status information from bulletin board signaling units. Each MET will be capable of transmitting signaling information to the GC on any of the inbound random access channels or on any of the inbound TDMA channels associated with the outbound TDM channel that it is receiving. During a call a MET will receive and transmit all signaling information via the In-Band signaling channels. No signaling information will be sent to a MET via the outbound TDM channel during a call. Any signaling messages from the GC to the MET will be sent to the MET via the FES through the GC-I and FES-C channels.

Each group controller supports at least one

outbound TDM channel in each of its associated L-band beams. Each outbound TDM signaling channel is

continuously transmitted and carries frequency

assignments and networks status information from the GC to the METs. The outbound TDM channels are also used to poll idle METs to see if they can accept incoming calls. As this channel is the only way to signal information to a MET not engaged in communications, it must be as robust as possible under harsh fading and shadowing conditions.

Another key element in the MSS system is the need for the METs to be as inexpensive as possible. Towards this end, the outbound TDM channel will have the same rate and modulation as the communications channels.

This will maximize the commonality of the receive chain of the MET for communications and signaling. Note that as the demodulation process is much more complex than the modulation process, the inbound random access and inbound TDMA channels do not really require this level of commonality with the communications channel.

The number of outbound TDM channels assigned to each set of signaling channels is determined by the traffic supported by the group controller in that L-band beam. Assignment of METs to outbound TDM channels is made based on a special identifier assigned to each MET as commissioning. This identifier is called the GC-S Selector Identifier code (GSI). The MET selects the outbound TDM channel to be used by dividing the GSI by the total number of outbound TDM channels available in the given beam. The number of TDM channels

available is given in the BB of each TDM channel. The remainder of the four bit binary division process will form the number of the channel to be used. Each MET will receive only the outbound TDM channel assigned to it. This method allows METs in the same logical grouping to be assigned to the same outbound TDM channel as is needed for the Virtual Network Service provided by the MSS System. It also allows the load on the outbound TDM channels to be redistributed quickly if a channel fails or a new channel is added.

The 120 ms frame length was chosen because it would support 6 messages per frame and correspond to the slot size requirement (>120 ms) of the inbound TDMA channel. This allows a direct correspondence between outbound TDM frames and inbound TDMA slots for the purposes of TDMA synchronization and scheduling responses to outbound messages. Eight flush bits are included at the end of each frame to allow the decoder to reset to a known state at the beginning of each frame. This allows more rapid reacquisition following channel fade events. The modulation scheme and transmission rate for this channel will be the same as for the

transmission channel, namely QPSK modulation at a transmission rate of 6750 bps. Signaling units within each frame will be coded with a rate 3/4 constraint length K=7 convolutional code.

The outbound TDM superframe has a duration of 360 ms and is made up of three outbound TDM frames. The superframe duration is the basic time interval over which message repetitions are done. Repetitions are used to increase the reliability of outbound TDM signaling units. Messages can be repeated in

consecutive superframes. Studies by AUSSAT have shown that L-band fade events typically have durations ranging between 10 ms and 100 ms (2). Because the 120 ms frame would not provide adequate separation between message repetitions, the 360 ms superframe is used to reduce the chance of losing two copies of a message during the same L-band fade event. This repetition method is similar to that used in the AUSSAT system. Different numbers of repetitions may be used for different message types to provide different levels of reliability. The number of repetitions used for a particular message type will be a part of the signaling protocols and can be varied by the system operator. In addition to message repetitions, interleaving will be used to protect against burst errors. The interleaving is provided over a TDM frame and provides improved performance in the presence of short burst errors.

The bulletin board is a set of signaling unit (SUs) that are periodically transmitted by the MCC on all outbound TDM channels. The bulletin board contains global information such as current network status, signaling channel frequencies and inbound random access channel congestion control parameters Every MET processes the information in the bulletin board METs, on startup, and acquires the entire bulletin board before attempting to use the MSS system. At least one bulletin board SU is transmitted in every outbound TDM frame. Bulletin board SUs are also sent as "filler" SUs, i.e., sent when there are no other SUs pending on the outbound TDM channels. Bulletin board SUs do not occupy any fixed position in the outbound TDM frame.

Bulletin board SUs are grouped into pages of related SUs. Each Bulletin Board page has an update number associated with it, which will be sent with each SU of that page. This number will be incremented by the NCC whenever the information in that page is updated. METs are required to build a local data structure that contains the contents of the bulletin board. Whenever a change in update number is detected for any page, the MET will update the entire data structure for that page with the contents of the bulletin board SUs that follow.

The inbound TDMA channel is used by the METs to transmit responses to call announcement messages and for responses to other messages received on the

outboard TDM channel. Each of the inbound TDMA

channels is assigned to a particular outbound TDM channel . The number of inbound TDMA channel assigned to a particular outbound TDM channel depends on the traffic supported by that outbound TDM channel and is selectable by the network operator. The TDMA channel is divided into slots of 120 ms duration. Inbound messages consist of 96 bits before coding and 128 bits after rate 3/4 convolutional coding. The resulting burst will occupy 80 ms of the slot, allowing 40 ms of guard time.

This guard time arises due to the uncertainty in round trip transmission time between the satellite and a mobile terminal. Mobile terminals derive their inbound frame timing (for both the TDMA and random access channels) from the outbound TDM frames. Inbound TDMA slots have the same duration as an outbound TDM frame. At a MET each TDMA slot boundary occurs at an outbound TDM frame boundary. If MET A is nearer to the satellite than MET B, MET A will receive the outbound TDM channel Δt sooner than MET B, where Δt corresponds to the difference in propagation times to the satellite for the two terminals. As a result, if both METs synchronize their transmit timing to their reception of the outbound TDM channel, MET B's responses to messages will take 2Δt longer to reach the satellite than MET A's responses. As additional guard time of 1 symbol time also must be included to account for the ± 1/2 symbol synchronization uncertainty in the MET. This results in a total guard time requirement of 2Δt + 1 symbol time.

TDMA scheduling is done using a fixed relationship between outbound TDM channel time slots and inbound TDMA channels and slots. The response to a message received in the nth slot of the outbound TDM frame is transmitted on the nth TDMA channel assigned to that outbound TDM channel. The frequencies of the assigned inbound TDMA channels are contained in one of the bulletin board signaling units periodically transmitted in the outbound TDM channel. The response to an outbound message is transmitted in the TDMA time slot that begins 120 ms after the end of the TDM frame in which the outbound message was received. This should provide adequate time for message processing in the MET.

The inbound random access channel is used by the

METs to transmit call requests to the GC. It is also used to carry other inbound messages for MET originated actions. The number of inbound random access channels assigned to a particular control group in a particular L-band beam depends on the traffic supported by that control group in that beam and is selectable by the network operator. To provide reasonable call setup times and call loss probabilities these channels are typically be operated at a throughput of approximately 25% or less. As the random access channel is operating at a relatively low efficiency, one of the prime goals in its design is that it be bandwidth efficient.

The frequencies used for the random access channels are transmitted in the bulletin board signal units. For each transmission, METs choose at random among the inbound signaling channels assigned to their control group. After transmitting a message, the MET waits a given amount of time for a response. If no response is received within this amount of time, the MET

retransmits in a slot selected at random over some given number of slots. This procedure is repeated until either a response is received or a maximum number of transmissions is reached. The bursts on the random access channel are identical to those on the TDMA channel (i.e., modulation, coding, preamble, etc.).

The MET-GC Signaling Protocol (MGSP) procedures send signaling units between GCs and METs via the GC-S, MET-ST and MET-SR channels. This protocol encapsulates functions such as channel selection, channel access, slot timing, error recovery and congestion control. Higher layer functions, such as call processing, use the protocol for communicating among themselves between the METs and GCs.

A transaction consists of a command message that is sent from an originating application to a destination application, to which the destination application replies with a response message. Each command and response consists of a signaling unit. The MGSP performs functions such as channel selection, error recovery using retransmission, and repetition of SUs to improve channel reliability. The MGSP at a MET also implements congestion control procedures for the MET-SR channels. Only one outstanding transaction exists between a MET and a GC in a given direction. However, two simultaneous transactions, one in each direction, are supported between a GC and a MET. MGSP also provides a only-way message service, that does not require a response from the receiver.

The improved call setup protocol used to establish a MET originated voice call is shown in Figs. 8a-8b. When a MET user initiates a call, the MET formats and transmits an access request message via a random access channel. This message includes the call type and the destination phone number. The group controller chooses an FES to handle the call and sends frequency

assignments to the MET via the TDM channel and to the FES via the interstation signaling channel. The FES frequency assignment also includes the call type, the destination phone number to allow the FES to complete the call, and an access security check field used to verify the METs identity. The access security check field is generated by the group controller using the

MET frequency assignment and the MET key which is known only to the MET and the group controller.

After the MET receives the frequency assignment, it transmits a scrambling vector message to the FES. This message contains the initial vector to be preloaded into the FES scrambler at the beginning of each voice channel frame. Letting the MET randomly pick this vector provides some degree of privacy on the Ku to L-band link. The scrambling vector message also contains an access security check field generated by the MET using its frequency assignment and its key. The FES compares this field with that received from the group controller to verify the identity of the MET. When the FES receives the scrambling vector, the FES will check the validity of the METs identity. If the check fails, the FES will initiate a call release.

After receiving the scrambling vector message and successful authentication of the MET (see U.S.

application serial no. 08/565,036, filed November 30, 1995, entitled FRAUD DETECTION AND USER VALIDATION

SYSTEM FOR MOBILE EARTH TERMINAL COMMUNICATION DEVICE," incorporated herein by reference), the FES and the MET switch from call setup mode to voice frame mode and the FES completes the call to the terrestrial network user. The FES transmits voices frames to the MET to

effectuate voice communication. We have discovered that the coder/decoder which is used in the MET imposes certain constraints described below that require the signalling architecture to be adapted thereto.

Specifically, it has been determined that the voice coder/decoder performs the following functions that impact on the signalling architecture in the context of our mobile satellite system. The voice coder/decoder receives coded messages from the baseband processing and RF electronic system and decodes the message received from the satellite antenna unit for delivery to the interface unit that includes standard user interfaces. The voice coder/decoder processes speech to produce 6400 bps output. The inherent speech coding rate is 4150 bps, to which 2250 bps of error correction and detection is added. The coder/decoder encodes

160+/-4 samples of speech and converts it to 128 bits. The encoding function is called approximately every 20 ms to produce the 6400 bps bit stream. The

coder/decoder decodes 128 bits of speech and produces 160 +/- 4 samples of speech. The encoder/decoder also performs voice activity detection.

In accordance with the coder/decoder functions and operations, the coder/decoder includes a voice

activation timer or synchronizer that is used to determine and insure that a caller is present during the call setup process. The encoder determines that the voice communication is active when valid data appears at the output within two sub-frames or

approximately 40 ms . The encoder determines that the voice communication is not active when no voice

activity occurs for 3 sub- frames or approximately 60 ms . The decoder sets the voice activity to active when voice activity is detected, and to inactive when no voice activity is detected.

In accordance with the above constraints of the coder/decoder, it has been determined that the protocol used by the mobile satellite system must be adapted for use with the standard encoder/decoder used for voice communication. In particular, it has been determined that the inherent delays in the mobile satellite system are incompatible with the voice activation timer used in the coder/decoder. In this connection, it has been determined that it is beneficial to eliminate usage of the voice activity timer during the voice mode prior to completion of call setup. Once call setup has been completed, the voice activity timer can then be reenabled and used for its intended purpose, i.e., to determine whether the call is still active or whether the call has terminated, thereby freeing up satellite resources more expediently.

Accordingly, once voice frames have been

transmitted from the FES to the MET in the voice mode, and once the FES transmits the destination number to the PSTN, the FES also transmits a voice activation disable signal to the MET to disable the voice

activation timer in the MET. The voice activation timer is then disabled for at least 3 super frames. After the FES has completed call setup with the GC, the FES transmits a signal to re-enable the call activation timer in the MET.

The PSTN provides ringing tones to the FES

indicating that the call is being placed to the

destination, and the FES in turn transmits the ringing tones to the MET. When the destination telephone answers the MET originated call, an off-hook signal is transmitted from the PSTN to the FES, and the FES in turn transmits same to the MET indicating that the call has been answered by a user connected to the PSTN.

Voice communication between the MET and the PSTN destination via the FES is then commenced until either party terminates the MET originated call. The improved protocol used for PSTN originated calls is shown in Figs. 9a-9b. When a call from a terrestrial network user arrives at an FES, the FES makes a channel request using interstation signaling. This request contains the phone number received from the terrestrial network user. The group controller determines the MET identity based on the phone number and transmits a call announcement via the TDM channel. The MET acknowledges this announcement via the TDMA channel. This exchange allows the group controller to verify that the MET is available before assigning bandwidth to the call . Frequency assignments are then made and the scrambling vector is transmitted by the MET once the MET tunes to the assigned frequency.

Upon successful reception of the scrambling vector, the FES checks the validity of the MET's identity. If the check fails, the FES initiates a call release procedure. If not, the FES transmits the ring command to the MET. Upon reception of the ring command by the MET from the FES, the MET generates a ringing signal to the MET user and transmits a ring command

acknowledgement. The ring command acknowledgement is repeated by the MET until the MET is taken off -hook by the MET user or until the call is cleared. Upon receipt of the acknowledgement from the MET and once the call setup is complete, the MET begins transmitting voice frames to the FES and also transmits a voice activation disable signal as described in connection with MET originated call setup procedure. Once the MET is taken offhook the MET switches to the voice frame mode. Upon detection of the MET switching to the voice frame mode, the FES stops transmitting null signal units, switches to the voice mode, transmits a voice activation enable signal and commences voice

communication between the MET and PSTN. MET to MET calls are set up using a double hop connection through an FES. These calls are set up by the group controller and the FES as a MET to PSTN call setup concatenated with a PSTN to MET call setup. As a result the METs require no additional call processing for MET to MET calls. That is, the procedures at the MET for receiving a MET-MET call are the same as procedures for reception of PSTN-MET calls, and the procedures at the MET for originating a MET-MET call are the same as procedures for origination of MET- PSTN calls .

Advantageously, the MET combines three different features for the delivery and transmission of voice and data. These three features include: the ability to initiate and transmit a data call, the ability to initiate and transmit a facsimile digital call, and the ability to roam between satellite and terrestrial based wireless communication systems. The following

documents, representing applicable transmission

protocols, are hereby incorporated by reference:

EIA/IS-41B Cellular Radio Telecommunications Inter-System Operations; EIA/TIA-553-1989 "Cellular System Mobile Station - Land Station Compatibility Standard"; EIA/TIA-557; EIA/IS-54B.

The improved NOC functional architecture is shown in the block diagram of Fig. 10. The NOC collects information pertaining to the utilization of resources and distributes information to appropriate destinations such as CMIS and NE/SE. The NOC is involved in network security to prevent unauthorized use. The blocks shown in the figure broadly represent the functions that the NOC performs or oversees. The network management is a framework for the NOC basic functions. The

configuration management implements and allocates resources in cooperation with plans formulated with NE/SE. The operator interface serves a fault management function. Problems in the system are isolated and reported to give operations personnel the ability to see when problems occur and react to them. The operator interface is a man-machine interface (MMI) to present alarms and events to the operators.

Information as to system configuration is also made available. Call records management serves as an accounting functionality. This function accepts MET registration records and other information sent by external entities for storage in appropriate NOC database tables. Usage data sent by the individual GCs and FESs are assembled into Call Records. Data

management serves as a data base repository for

transmission and receipt of information gathered by the other components of the network operations center.

Figs. 11A - 11C set forth the NOC architecture in more detail, the elements shown corresponding to the blocks of Fig. 10. As shown in Fig. 11A, the network management block contains Polycenter Processes modules that serve alarm manager, exporter, historian and operator control functions. The historian records performance of the network over time, collecting at suitable intervals statistics regarding resource utilization, calls in progress. The management

information repository (MIR) server interfaces with the exporter. Network update requests are received from the router. When transactions come in from NE/SE or CMIS, they need to be distributed to different parts of the system. Updates are distributed to the MIR server so that it can update the internal data base. After all elements of the system are set up, network updates are communicated back to the router for network

implementation. Exporter transmits collections of information, including performance traffic data, to the database in the data management block. The NE/SE system is described in detail in U.S. application serial number 08/601,749 filed on February 15, 1995, incorporated herein by reference. The CMIS system is described in detail in U.S. application serial number 08/598,556 filed on February 8, 1996, incorporated herein by reference.

The alarm rule manager sets thresholds for adverse conditions and executes set up procedures for the event management block. For example, if customer service center sends out a commissioning request and the commissioning fails, an alarm is generated and the NOC sends a message to CMIS describing the failure and the cause of the failure. The watchdog looks for events, such as the system disk becoming fully utilized and other fault conditions, and sends an alarm to NMS to operator screen. The performance data collector samples resource utilization, collects statistics and provides feedback. NOC process control is involved with custom processes such as NOC startup and shutdown.

Configuration updates are received by the

configuration management block, shown in Fig. 11A. A routing table is used to distribute messages to the appropriate components of the NOC.

The data management block, illustrated in Fig. 11B, includes servers to interface with the NOC main data base (DB) . The RTR router receives RTR requests from either satellite resource manager or configuration management. The NOC configuration DB server decides from polling NOC components whether the request for update is to be accepted. If so, the NOC data base (DB) is updated and confirmation is sent to other components to update local data bases. The request is basically distributed to all other components to vote on the appropriateness of the requested change. For each transaction there is a specific set of data bases that are to be updated. DC Comm exports information from the database to NE/SE and CMIS. As read transactions do not need to go through this voting to update process, accessing for reading is easily

available to any of the system components. Performance data, collected in the network management collector, previously described, is periodically exported directly to the data management DB, as no updating of other module databases is needed. Such data is not related to the overall configuration.

The call records management block is shown in Fig. 11C. The functionality of this component accounts for customer usage to enable billing preparation by the configuration management information system (CMIS). Call detail records (CDRs) relating nonsatellite usage are received from the gateway switch (GWS) and call performance records (CPRs) or call usage records

(CURs), relating satellite usage are received from the group controller (Gc) . These records are logged into files at the GWS and CUR/NRPR servers to be forwarded to CMIS and saved as backup in the data base. The call trace router sends RTR requests for call tracing and trapping to and from the GC. Call tracing requests are sent to the trace operator, shown in the operator interface block of Fig. lie. Call trace information is received by the call trace router from the trace operator.

The operator interface includes the session

manager. After logging in to the session manager, each of the functions represented by the other blocks within the operator interface block is available. When the system is started or restarted, the

encryption/decryption code is established. The MT ASK (Access Security Key) block, essentially a separate data base, contains specific keys specific to each telephone and is checked in real time for each call. The mobile telephone (MT) key is set up when the new MT is added to the system. MT ASK is also used for storing CMIS and GC encryption keys used for encrypting request transactions. The operator message (Op. Msg.) block is an interface for E-mail. Resource allocation MMI permits the NOC operator to modify the system for day to day operations, such as taking resources off line or on line. The DB access permits the operator to read the data base DB . Bulletin Board records

containing transmit and receive frequency information about the METs are available to the operator from the Site Manager location.

The event management block, involved with fault management, is shown in Fig. 11B. All messages are received in the event logger, logged to a file, sent to a printer and displayed at the NOC MMI . Where

necessary, files are forwarded to external

organizations such as CMIS or NE/SE. CGS

(communications ground segment) event data are sent to the CGS event sink. The COTS (Commercial off the shelf) software sink receives other events, such as VMS events. The watchdog event sink receives events from the watchdog block in the network management block, described above. The operator communication (OPCOM) generator converts VMS events into a common format.

Fig. 12 illustrates the Network Communications Center (NCC) and the elements contained therein. The Group Controller (GC) resides in the Network

Communications Center (NCC) system element within the CGS and provides call control and satellite resource management for:

- Circuit-switched voice, FAX, and data calls; - Integrated Voice and Data MT (IVDM) voice calls;

- Satellite trunked radio calls.

The GC controls setup, monitoring, and cleardown of calls between MTs, IVDMs, VN MTs, and terrestrial users. It also provides AMS (R) S Provisioning, Control Group Reconfiguration, MT and FES PVT and Commissioning support, and Performance and Status Monitoring.

The primary function of the GC is the management of customer Control Groups. Control Groups identify groups of MTs/IVDMs which have access to CGS, the satellite and network resources that have been

allocated to them for sending/receiving calls, and the service permissions and calling restrictions that apply to each MT/IVDM. Control Groups also contain Virtual Networks (VNs) discussed below, which define the routing options that apply to each MT or IVDM in the Control Group and Circuit Pools, which control the allocation of use of satellite circuits for circuitswitched calls.

Fig. 13 illustrates the NCC logical architecture.

The Group Controller consists of five top level

components which perform the following functions:

1. Call Management

This component performs:

- Call setup/monitoring for:

a. MT-to-MT, MT-to-PSTN/PN, PSTN/PN- to-MT calls b. MT initiated VN Calls

c. Dispatch initiated VN, Private Mode,

Broadcast, and Priority 1 calls.

- MT Management, including:

MT Logon, GC-S Change, MT Shutdown, and MT Parameter Update, Visitor Registration; - Preemption of calls for AMS (R) S provisioning of satellite bandwidth and power.

- MT Commissioning and PVT.

2. Resource Management

This component performs resource management and reconfiguration, including:

allocation/deallocation of satellite resources during call setup/cleardown - incremental/complete reconfiguration of local Control Group databases

- address screening

- MT authorization

- call routing

- Virtual Network configuration

3. Configuration Management

This component performs executive control for: - Control Group configurations;

- AMS(R)S requests

4. MT ASK Management

This component performs:

- secure MT ASK database management

- real-time check field generated for call

processing

- ASK generation after completing

commissioning/PVTs for Enhanced Fraud

5. Utilities

This component is the common utility set for the GC including:

- MGSP

- Call Record Management

- Performance and Traffic Statistics generation - Congestion Control

- Memory Management

- X.25 interface.

The NCC provides real time call processing for users of the CGS by assigning resources on a per call basis. The NCC operates under the administrative control of and is monitored by the NOC. The NCC manages access of users of the space resources

allocated to the NCC by the NOC. The NCC provides system monitoring and testing functions to support FES and MT commissioning and periodic performance

verification testing. A single NCC provides these functions for an entire network carrying the full traffic load. In the event that the NOC is not

available, the NCC contains a backup operator interface capable of monitoring and controlling the ongoing provision of services to customers and which is capable of providing emergency AMS (R) S provisioning.

Logically, the NCC is divided into two functional groupings, namely RFE and processing/management

functions. Physically, the NCC is similarly divided into RFE and terminal equipment which performs the processing and management functions. The NCC terminal equipment is composed of an integrated set of hardware that is shared with the NOC and FES elements. From the NCC perspective, the hardware is composed of three sets of equipment which include the Circuit Switched

Management Processor (CSMP), Network Access Processors (NAPs), and Channel Units (CUs). The NAP functions for the NCC consist of Network Access Processors for

Signaling (NAP-S), Network Access Processors for

Communications and Testing (NAP-C (Test)), and Bridges Modems for Interstation Signaling Channel Units Both the NAP-S and NAP-C (Test) have channel units associated with them. The NAPs, Bridges and Channel Units

together form the NAP-CU HWCI There are two styles of NAPs, namely, the Circuit Switched NAP and the Data

NAP. The Circuit Switched NAP performs the out-of-band signaling (NAP-S) functions or communications (NAP-C) functions.

A block diagram of the circuit switched NAP is shown in Fig. 14. The NAP is PC-based and contains a processor card, and SDLC card forming the interface with up to 24 channel units, an ethernet card providing the interface to ethernet B in the CSMP, and a

distribution card. The distribution card provides a DS-1 interface between the gateway or base switch in the FES and the communications channel units, and a frame clock distribution function between the RF equipment and the out-of-band signaling channel units. NAPs are used in pairs for redundancy with an on-line and an off-line NAP or NAPs A & B. Each NAP monitors the condition of the other and takes over processing when a failure is detected or by operator (NOC or backup NCC) command via the system common software CSCI Site Manager function. The NAP-S and NAP-C connect to a channel unit of the same type which forms the

interface to the RFE for signaling and communications. The CUs are hardware identical and take on their operational personality (S or C) with a software download when they are initialized.

A block diagram of the CU is shown in Fig. 15. The CUs are composed of two major sections: the Baseband Signal Processor Unit (BSPU) and the Channel Signal Processing Unit (CSPU). The CU interfaces to the NAP are shown on the left and the interfaces to the RFE are shown on the right. The sub-element processor types are noted in the diagram.

The BSPU is composed of three major functions: the SDLC Controller (Z80235), Monitor & Control (80186EC) and the voice/modulated data processing (twin

TMS320C31). The SDLC Controller provides the interface between the main and redundant NAPs. The Monitor & Control function provides the central control and status focus. This processor also supports the

software downloads to a given CUs set of processor sub-elements. The pair of TMS320C31 processors provide the functional processing for echo cancellation, rate adapting and detection, mu-law linear decompression, CODEC, voice, voice modulated data, FAX.

The CSPU is composed of a DSP, I/Q channel A/Ds & D/As, L-Band transmit synthesizer and L-Band receive synthesizer. The major functions performed by the DSP include data framing, encoding/decoding, interleaving, scrambling/descrambling. The DSP operates on digital data from the receive synthesizer A/Ds and supplies digital data to the D/As for transmission via the transmit synthesizer. As noted earlier, there are up to 24 CUs controlled by a single NAP pair (i.e., main/redundant).

The NCC element is composed of a GC CSCI hosted on the CSMP, a NAP CSCI hosted on the NAP processor and the CU CSCI hosted on the set of CU processors as shown in Fig. 15. The NCC element also requires some

portions of the SCS CSCI which is hosted on the CSMP. Both the NAP CSCI and the CU CSCI require a

communications version and a signaling version of these SCS CSCIs. Both versions execute on the same physical H/W configuration type. The functions of the NCC element are implemented by a set of software processes as follows:

The SCS CSCI is primarily responsible for network management functions. Software and hardware objects are managed and status and events reported to the NOC.

The NAP CSCI performs both call processing and network management functions. Interaction with the GC is established for receiving the GC-S signaling units for transmission via the SCU to the MTs. The NAP also returns to the GC the SUs received from MTs via the MT- SR and MT-ST channels.

The GC CSCI includes the following databases:

In the preferred system configuration, the Group Controller resides on one VAX ft 810 and executes in multiple concurrent asynchronous VMS processes which timeshare the CPU. The functionality of each GC process is as herein described.

The GC is made up of the VMS processes listed below. There are two Process Groups: the GC

Controller (GCC) group, and Control Group Management (CGM) group. The GCC and CGM Process Groups are described below.

Highest priority is given to the real-time

processes for call handling. Second priority is given to near-real-time processes, which support call

handling by forwarding call records and supplying call traffic and performance data to the NOC. Third

priority is given to the non-real-time processes which support ASK and Control Group reconfiguration at the GC.

The GC processes are event-driven; between events, a process waits for input on a queue. To reduce system load, waits are non-CPU-intensive. The highest

priority processes are driven by call events; the lowest priority processes are driven by NOC requests, Call Process requests, and internal timers set to configurable monitoring intervals. In addition to input from its queue, a process may use memory tables or disk files, as shown on the Process Diagrams, for data required to process an event.

The GC architecture accommodates a move to multiple processors. The GC is divided into GC Controller (GCC) processes, and Control Group Manager (CGM) processes. In a distributed environment, there would be one GC Controller, consisting of the GC Router and both ASK Manager processes, supporting one to 16 Control Group Managers. CGMs function independently and can be distributed on multiple processors. A CGM can manage 1 to 16 Control Groups, so there can be one CGM for all Control Groups (the current configuration) or up to 16 distributed CGMs (one CGYM for each Control Group). All processes for a CGM must be co-resident. The GCC can share a processor with one or more CGMs, or can reside on a separate processor. The ASK Manager is stand-alone, and can be hosted on a separate processor in any GC configuration.

GC Subsystems illustrated in Fig. 16 comprise the component subsystems in the Group Controller and indicate where call processing and network management interfaces occur.

Configuration Process

The Configuration (Config) Process has multiple configuration control tasks. The Config Process controls the GC processing of Control Group

reconfigurations. It receives database transactions from the NOC via the DEC COTS product Reliable

Transaction Router (RTR), prepares the update, loads the new data into memory, and coordinates with the Call Process to complete the update. The processing and synchronization of the Config and Call processes during a configuration change is designed to minimize

interference with active calls. ASK reconfigurations are handled by the ASK Configuration Manager.

The Config Process performs dual RTR roles. It performs as a server in NOC-initiated updates (#1, above) and a requester (client role) in GC-initiated database updates. As an RTR requester, the GC

initiates RTR transactions to distribute changes that originated in the GC Call Process. One example of a GC initiated update is the change of a MT state following commissioning; another is the GCs initiation of a bulletin board update for congestion control.

Config receives AMS (R) S circuit requests, sends circuit blocking commands to the Call Process, and returns the requested circuits to the NOC when they become available.

The Config Process has one RTR queue for

reconfiguration messages from the NOC, including

AMS (R) S requests. It also has a VMS mailbox for the CGS Software Backplane Process Control interface, and a mailbox for internal timer notification. Call Process

The Call Process is the heart of the real-time GC processing. It incorporates the Finite State Machines (FSMs) for Call Processing, MT Management, AMS (R) S Provisioning, and PVT/Commissioning. It also contains resource database access routines, error handlers, timers and utility functions that support the FSMs.

The input queues are prioritized as indicated on the GC CGM Inter-process Communications Diagram.

Incoming messages from each queue are processed in order. When an FSM message/event is processed, the Call Process maps the message or event to its state data, performs the state transition processing, and establishes the next state. Errors occurring in a state transition are handled by error routines

associated with the current state in the FSM. State data is maintained in the Active Call Record Table, which allows shared read-access for use by support functions in the Monitor process

The Call Process has one input queue established via the CGS Backplane for signaling units, and Access security Check Fields (generated by the ASK Manager). It also has VMS mailboxes for the CGS Software

Backplane Process Control interface, internal time notification, internal messages (such as Circuits Available), AMS (R) S requests, and control group reconfiguration requests from the Configuration

Process.

Monitor Process

The Monitor Process provides the following Call

Process support functions:

1. Forward Call Records to the NOC

2. Buffer Call Records on disk

3. Save the MT Access Event History on disk

4. Generate call traffic statistics 5. Respond to Call Search Requests

6. Respond to Call Record Leftover Requests

Items 1-3 above are performed when a Call record is terminated. The monitor process receives the Call Record from the Call Process, in a Call Termination message. This process forwards the final Call Record data to the NOC, increments counters for call

statistics, stores the Call Record on disk for backup in case the NOC goes down, and stores the MT Access Event History on disk. the MT Access Event History buffers that last ten accesses by MT by storing the time stamp of the end of the call, termination reason, and access type (such as MT Management, Call, NR, etc.).

Statistics (Item 4) are generated by the Statistics

Manager and polled by the Site Manager (DECmcc Agent) at configurable time intervals. These data are derived from the Call Process (via the terminated Call

Records), and stored in shared memory tables for the Site Manager (DECmcc Agent).

Call Search requests (Item 5) are sent by the NOC to request the current Call Record (if one exists) of a specific MT, and its Access Event History. The Monitor has read-access to the Active Call Record Table

maintained by the Call Process for retrieving the call ID and call record, if it exists, for a MT.

Call Record Leftover requests (Item 6) are sent by the NOC when they are back online after some period of down-time. The request contains the ID of the last Call Record received by the NOC. The Monitor Process retrieves later records which it buffered on disk while the NOC was down.

The Monitor process has one input queue,

established via the CGS Backplane, to receive Call Record Requests and Call Search Requests requests from the NOC. It has a VMS mailbox to receive terminated call records from the Call Process, a mailbox for the CGS Software Backplane Process Control interface, and a mailbox for internal timer notification. GC Router Process

This process routes Call Process messages which do not have a Control Group ID. The GC Message Router Process has one input queue established via the CGS Backplane to receive incoming SUs for internal routing. It also has a VMS mailbox for the CGS Software

Backplane Process Control interface, and a mailbox to receive reconfiguration messages from the GC Router Configuration Process.

GC Router Configuration Process

This process is an RTR server process to accept reconfiguration transactions from the NOC. This server is only notified of updates when the change affects the Control Group ID of a MT/MIN, IVDM. It cooperates with the router process in the same manner that the Config Process cooperates with the Call Process to complete a transaction.

Router

This Process has an RTR input queue. It also has a VMS mailbox for the CGS Software Backplane Process Control interface.

ASK Configuration Manager Process

The ASK Configuration Manager Process configures the ASK database, based on NOC inputs. The ASK Config Process has one RTR input queue. It also has a VMS mailbox for the CGS Software Backplane Process Control interface . Check Field Generator Process

The Check Field Generator generates MT Check Fields in response to Call Process requests. It also receives ASK reconfigurations from the ASK Config Process, which it stores in the memory-resident ASK database. This process has one input queue established via the CGS Backplane to receive check field requests from the Call Manager. This interface is via the Message Layer because the ASK Manager may not be co-resident with the Call Process it serves. It also has a VMS mailbox for the CGS Software Backplane Process Control interface, and a mailbox to receive configuration messages from the ASK Config Process.

GC Queues Inter-Process Communications Sequence

Example: MT-PSTN Call

1. When a MT Access Request is received on the real-time CALL event queue, the CALL process sets up the call record, establishes a MT Activity Table entry for the call and determines whether the dialed digits in the Access Request SU are complete.

2. If additional digits are required, the CALL process sends out a request to the MT (see following Note 1 and the following referenced notes) and sets a timer for the expected response.

3. When the additional digits are received, the

CALL process cancels the Additional Digits Request timer.

4. The CALL process validates the MT, performs address screening, service permission checks, and routing. If all checks succeed, it allocates circuits and updates the OFFLINE GC CALL UPDATES process.

5. The CALL process requests the Access Security Check Field from the CHECK FIELD process. It sets a timer for the expected response. When the Check Field is received, the CALL process cancels the timer for the request .

6. The CALL process sends out Channel Assignments to the MT and FES. It sets a timer and waits for the Setup Complete message.

7. When the Setup Complete is received from the SLSS, the CALL process cancels the Setup timer, updates the OFFLINE GC CALL UPDATES process, and sets a timer for the Call Status Monitoring interval.

8. When the Call Status Monitoring timer expires, the timer in the CALL Process notifies the Call Manager which sends out a Call Status Request and sets a timer for the response. When the Call Status Reply is received, the CALL process resets the monitoring interval timer.

9. When the Channel Release is received, the CALL process cancels the Monitor timer and closes out the call by releasing resources, clearing the activity table, and sending a call termination event to the MONITOR process.

10. The MONITOR process closes out the call record, updates the OFFLINE GC CALL UP-DATES process, performs any Statistics generation required, sends the call record to the NOC, and Buffers the call record to disk.

Note 1 : All messages to/from the MT are sent via the NAP-S.

Note 2 : If the response has not been received before the timer expired, the timer in the CALL process would have notified the Call Manager, which would have performed appropriate error handling.

Note 3 : The CALL process can process other calls while it awaits for a response from another process on any given call. GC Queued Inter-Process Communications Example

Incremental Reconfiguration

1. When a distributed database transaction from the NOC is received on the GCs RTR queue, the CONFIG process reads the transaction and prepares an update to the Local GC Configuration database. When the

preparation and validation are complete, the CONFIG process waits for a vote request from the NOC. The CALL process cannot access the new data until the distributed transaction is complete.

2. When the CONFIG receives a vote request via RTR, it returns the GC vote. The GC will return

VOTE/COMMIT if its local database validation and update preparation were successful, or VOTE/ABORT if an error occurred while processing the update. After casting the GC vote, the CONFIG process waits for a return code from RTR, indicating the final status of the

transaction. Final status is determined by RTR from the votes cast by all participants.

3. If the final status of the transaction is

COMMIT, then CONFIG sends a message to CALL informing it of the reconfiguration. CALL updates its links to the reconfigured data and acknowledges the completion of the update. CALL can now access the data.

4. When the update is complete, the CONFIG process sends a Reconfiguration Event to the NOC via the DECmcc AGENT process.

Both the Online and Offline GCs participate in a Control Group reconfiguration since the Offline GC serves as another RTR partner in each distributed

Control Group transaction. The processing is the same cases.

NCC On/Off Line Switchover Process

As noted earlier, the fully expanded CGS system includes a second NCC or alternate NCC. This separate physical copy of the NCC maintains near real -time communication with the active on-line NOC and the active on-line NCC via the MSS Internetwork using the TCP/IP protocol. The MSS Internetwork communication path allows the alternate NCC to be geographically separated from the on-line NOC and the on-line NCC. The near real time communication allows the off-line NCC to maintain a "hot" standby status such that it could become the active on-line NCC with a minimum amount of elapsed time and "lost processing" once the switch between NCCs is initiated.

In order to maintain an up-to-date status at the off-line NCC, the applicable database updates at the on-line NOC will be issued as RTR transactions to maintain lock-step database concurrence across the two NCCs. The categories of message sent to the off-line NCC include:

- MT Customer Configuration

- Virtual Network and Routing Configurations - FES Configuration

- Channel Unit Pool Configuration

- Satellite Resource Configuration

- Control Group Operation Parameters

- Bulletin Board Data

To maintain lock step with ongoing real time call processing, the off-line NCC receives call processing information from the on-line NCC on a call-by-call basis. The major categories of information moving from the off-line NCC to the on-line include the following:

- Call records with frequencies allocated to a call setup

- Call records for a call after setup is complete - Call record for a call after the frequencies have been released.

The off-line NCC uses this information to maintain call records and frequency allocations dynamically such that the off-line NCC can immediately assume control of the in-process active call suite and is completely aware of the current in-use frequencies to continue with new call setups and "old" call releases.

The on-line to off-line NCC switch over may occur as scheduled activity ( e . g. , periodic maintenance, major NCC H/W or S/W configuration upgrade, etc.) or as a result of a failure of the current on-line NCC.

The scheduled switch over process is the following: - The on-line NOC or local NCC operator alerts the on-line NCC to initiate processing phase out and suspend active communication with its associated CGS internal element.

- The on-line NCC alerts the off-line NCC that all processing has been suspended and all elements associated with the NCC are waiting for a communication restart.

- The off-line NCC commands the on-line NCC to go to passive standby under its own local operator control. At this point the previous off-line

NCC is now the new active on-line NCC. - The new on-line NCC begins a communication

restart sequence with its associated CGS elements .

This completes the scheduled switch over from an active on-line NCC to the off-line NCC.

The fail over process is initiated by the on-line NOC. The process flow is the following:

- The on-line NOC commands the on-line NCC to go to passive standby under local operator control. This is an insurance command to attempt to eliminate the failed NCC from active participation in CGS processing.

- The on-line NOC commands the off-line NCC to go active. - The on-line NOC commands all NCC associated elements to suspend communication with the old on-line NCC and wait for an NCC communications restart command.

- The on-line NOC commands the new on-line NCC to begin a communications restart with all of its associated elements.

- The new on-line NCC begins a communications

restart sequence with all of its associated elements.

This completes the fail over sequence. If the original active on-line NCC is not capable of fulfilling its role in the fail over sequence, the switch over will be accomplished via NOC operator to NCC operator

communication to suspend the operations of the original on-line NCC and then via NOC MMI to command the on-line NOC MMI to command the on-line NOC to pick up the remainder of the failover sequence.

The Gateway Switch (GWS) is the communications hub for Feederlink Earth Stations (FESs) to provide call processing services to MT users and handles cellular Intersystem Handoff (1HO), Automatic Roaming (AR) and Call Delivery (CD) .

The GWS provides the following interfaces:

• Public Switched Telephone Network (PSTN)

• Private Network (PN)

• Cellular Terrestrial Network (CTN)

• Network Operations Center (NOC)

• Station Logic and Signaling Subsystem (SLSS) • Network Applications Processor (NAP)

The GWS acts as a gateway between the users of the satellite system and the Public Switched Telephone Network (PSTN) , Private Networks (PN), and Cellular Terrestrial Network (CTN) . Within the FES, the GWS connects through Communication Channel Units (CCU) and the satellite system for bearer channel connections to Mobile Terminals.

The GWS also connects through a Station Logic and Signaling Subsystem (SLSS) for a control path to and from the Network Control Center (NCC). The GWS views the MSS call processing resources as cell site(s). The cell site emulation performed by the GC, SLSS, NAPs, and CUs allows the satellite system to be configured into the DMS-MTX as an analog cell site.

With respect to the MSS, the basic functions of the

GWS are:

• manage the PSTN/PN interfaces

• manage CTN interfaces

• receive and process connections and feature control messages from the SLSS processes

• provide various operational and administrative

support for the switching operations of the network

• provide various Call Service Features to the MT

user The basic role of the GWS within the Mobile

Satellite Services (MSS) system is shown in FIG. 17. As indicated, the GWS acts as a gateway between the users of the satellite system and the Public Switched Telephone Network (PSTN) or Private Networks (PNs). Within the FES, the GWS connects through Communication Channel Units (CCUs) and the satellite system for bearer channel connections to Mobile Earth Terminals (METs). The GWS also connects through a Station Logic and Signaling Subsystem (SLSS) for a control path to and from the Network Control Center (NCC).

In contrast to the hardware interfaces shown in FIG. 17, FIG. 18 depicts the basic call processing interaction between the GWS and other elements within and outside of the overall MSS system. As indicated, standard Call Processing (CP) software within the GWS interfaces with a Call Control Element (CCE) process in the SLSS and with a Group Controller (GC) processing the NCC.

With respect to the MSS, the basic functions of CP in the GWS are: to manage the PSTN/PN interfaces, receive and process connection and feature control messages from the CCE and GC processes, and provide various operational and administrative support for the switching operations of the network.

In addition to the internal interfaces of the MSS, the GWS CP also interfaces CP control elements of the PSTN or the PNs. In the most basic applications the various CP processes only exchange addressing (dialing) information for call routing. In more advanced

applications involving SS7 or ISDN networks, the CPs exchange information for advanced features such as calling number identification, terminal

characteristics, calling restrictions, subaddressing, routing requirements, etc.

Note that since the GWS is expected to be a variant of a public network switching system, there will be functional similarities between the GWS CP and the PSTN CP and PN CP.

The GWS physically resides as part of the

Feederlink Earth Station (FES) (see FIG. 17). The FES is the network interface point for the interconnection of satellite resources and terrestrial resources. The GWS can best be envisioned as an end-office, connecting to Mobile Earth Terminals (METs) in lieu of subscriber telephones. The METs are special purpose terminal sets communicating, via satellite, to the Feederlink Earth Station.

The METs, in conjunction with other functionality of the FES, can provide circuit switched voice, data and facsimile services. A highly compressed method of voice encoding is used over the satellite channel. Likewise, the satellite channel can accommodate 4800 bps digital data which is converted to voiceband modulated data (in a Hayes compatible modem format) in the CCU which interfaces to the GWS. In addition, the system supports facsimile traffic complying with the

Group 3 standard. Not withstanding the above, services appear at the GWS via 64-kbps (DS-0) bearer channels contained within T-1 physical links. Signalling related to MET originated calls is handled via separate signaling links from the SLSS as described

subsequently .

The GWS supports the MSS network provision of

Mobile Telephony Service (MTS). MTS is defined as voice, circuit switched data, and Group 3 FAX. At the highest functional level, the following telephony functions shall be supported in the MSS.

• Establish, maintain and disconnect Mobile Earth

Terminal (MET) circuit switched connections.

• The generation and reporting of Automatic Message Accounting (AMA) events to be used for subscriber billing and operations purposes.

• Support of Operations, Administration and

Maintenance (OA&M) functions and interface to external support systems.

• Support and interface to voice messaging systems for the network provision of value-added features.

Circuit switched connections may be any one of the following :

• MET to MET

• MET to/from PSTN (IEC or LEC)

• MET to/from Private Network

• MET to Alternate Operator Services

• MET/PSTN/PN to Voice Messaging System

AMA records of call events shall be maintained and reported by the GWS. The basis for this functionality is LSSGR AMA compliant with some unique MSS data collection required.

The functionality of the Gateway Switching

Subsystem has been specified, to the extent possible, to be a generic PSTN, digital switching system. It is desirable to minimize the non-recurring engineering effort imposed on potential switch vendors. Toward this objective, the functional requirements are

functionally similar to Bellcore's LATA Switching

System, Generic Requirements (LSSGR) document,

incorporated herein by reference.

The one area recognized as requiring customized engineering is the interface to the satellite

resources, as described below.

The GWS interfaces are grouped into four

categories: the Telephone Network Interfaces, Mobile Access Interfaces, the Operations Support Interfaces and the Ancillary Equipment Interfaces. Communications Channel Unit connections are bearer circuits (64-kbps DS-0) carrying voice, circuit switched data or

facsimile. The connections to the Station Logic and Signaling Subsystem and the Network Control Center are signalling interfaces.

Operations, maintenance and administration

interfaces are to the Network Operations Center.

Ancillary interfaces, for example, to Voice Messaging systems are also provided. Telephony network

interfaces are shown to the left side of the GWS. PSTN interfaces will be to both the Local Exchange Carrier (LEC) and one or more Inter-Exchange Carriers (IEC). Multiple Private Networks must also be accommodated.

Alternate Operator Services (AOS) provided by other companies may be used initially for the support of Calling Card/Credit Card billing and operator assisted calling. This function may also be accommodated using so-called "robot operators" which are a specialized version of an Interactive Voice Response (IVR) system.

Trunk access to the PSTN is required. Physical access shall be via T-1 facilities. Extended

Superframe format T-1s with ANSI recommended alarms and performance reporting is highly recommended. PSTN access shall support in-band, multi-frequency signaling to and from one or more IECs and the LEC.

Trunk access is also required to Private Networks. Again, physical access shall be via T-1 facilities with analog interfaces, if required, being accommodated with channel banks outside the scope of this specification. Again, ESF format T-1s are recommended.

Alternate Operator Services may be used in the network for the provision of operator assisted calls and credit card billing validation. Physical access to the AOS service provider shall be via T-1 facilities. Collectively, the resources required to support

satellite communications are referred to as the

Satellite Resources These resources include the

Communications Channel Units, Signaling Channel Units, the Station Logic and Signaling Subsystem and the

Network Control Center. Functionally, a GSM 'A' interface is recommended because it best accommodates the fundamental requirements of the satellite

interface.

The GSM Recommendation 'A' interface provides the two fundamental characteristics necessary to support the MTS requirements; 64-kbps bearer channels and out-of-band signaling channels. Out-of-band signalling is required to support the interactive nature of call processing between the GWS and the NCC. The NCC has responsibility for three primary functions, as related to the Gateway Switching Subsystem and call processing functionality. • Management and allocation of the Satellite

Resources

• Interworking with Cellular networks for Mobility Management

• Real-time management and administration of the

subscriber database

Because of this parsing of functionality, the GWS must interwork with the NCC (via the SLSS) on all call attempts. As originating attempts are presented at the Communications Channel Units, signalling and subscriber information, necessary for the handling of the call attempt, will be communicated across the SLSS signaling interface .

Likewise, terminating attempts from the PSTN or private networks, to a MET subscriber cannot be handled until the GWS and NCC have communicated to identify the satellite resources to be used, and any subscriber-related data necessary in processing the call.

The Communications Channel Unit interface shall be via DS1 cross connect facilities. Each DS1 cross connect signal provides 24, 64-kbps (DS-0) PCM

channels. Communications Channel Units have no fixed association with MET terminals or subscribers This association is supplied to the GWS on a per call basis by the NCC.

Note: A DS1 cross connect signal is functionally equivalent to a T-1 signal that is used for equipment interconnections between equipments in a building.

Because of the integral role that GWS/NCC

communications (via the SLSS) plays in call processing, the SLSS interface must be redundant, be traffic dimensionable, provide for reliable communication of messages, provide reliable communication subsystem recovery in the event of hardware or software failures, and support the OSI model for open systems

interconnection. Signalling System 7 (SS7) is recommended as the most robust signaling protocol available to satisfy these requirements.

The primary function of the Network Operations Center (NOC) is the non real time management and control of MSS resources. The GWS is required to interface with the NOC for the following functions.

• System surveillance and monitoring

• Error logging and tracking

• Control of diagnostic testing and result analysis • Management of network restoration procedures

• Accumulation of AMA call events

• Database management and administration

• Accumulation and reporting of network performance statistics

• Accumulation and reporting of network configuration data

• Security Management

The Gateway Switching Subsystem shall interface to the NOC for its internal Memory Administration, AMA Teleprocessing, Network Management, Measurements and Statistic reporting and System Status Monitoring and Surveillance.

The NOC interface(s) shall meet OSI requirements for Open Systems Interconnection, such as X.25. The interface (s) shall support multiple physical or logical channels for each function. If multiple logical channels are provided on a single physical interface, each logical segment of the interface shall be

dimensionable based on the data through-put demands placed on it.

The Traffic Data Collection System is referenced as the interface for the communication of traffic

measurements and statistics to the NOC. This interface is specified in LSSGR FSD 45-09-0100. The GWS

interfaces with the NOC to provide remote memory administration functionality. The Memory

Administration Interface shall be provided per the requirements stated in LSSGR FSD 45-01-0701.

The GWS AMA Teleprocessing Interface is provided in the form of an AMA Transmitter (AMAT), permitting the store, poll and forward transmittal of GWS collected AMA records to the NOC. This interface meets generic requirements of an AMAT. Network management messaging is defined in Bellcore LSSGR, FSD 45-18-0403 and FSD 45-09-0100.

Remote Switching Maintenance Interfaces is provided in either synchronous or asynchronous form. Bellcore LSSGR FSD 35-08-0100 and FSD 35-08-0200 provide details of those interfaces. The synchronous interface is preferred. This interface supports a Voice Messaging System with the capability of delivering original called number identification for forwarded numbers so the voice messaging system can provide personalized greetings .

The Gateway Switch consists of multiple items illustrated in FIG. 19. The DMS-MTX SNSE is the main component of the GWS. This component provides the control to perform call management and system control functions. The SNSE was chosen for the optimal cost and size. This configuration supports a 16K port switch. The delivered hardware is Motorola 68020/20MHz based. The SNSE consists of the following sub-components:

• Message Switch (MS) - This component is

commonly referred to as the DMS-BUS. The DMS-bus is the messaging hub of the system. The message switch is a fully duplicated entity that provides message routing between system components. A 32 bit MC68020

microprocessor, supported by 6 megabytes of memory, manages the overall performance of the DMS-bus. • Enhanced Network (ENET) . The third shelf of the SCC cabinet contains the ENET. The ENET is a conventional matrix timeswitch designed to achieve high density at low power consumption. The ENET provides a duplicated, junctorless, nonblocking network. The ENET Cross-points are optimized for a 16K channel network.

• Computing Module (CM) - The bottom shelf of the SCC cabinet contains the CM. The CM is fully

duplicated, synchronized, computing module. The CM utilizes the 32 bit Motorola MC68020 microprocessor. There are 216 megabytes of call and program store capacity (maximum growth) in each CM.

• System Load Module (SLM) - The bottom shelf of the SCC also contains the SLM. The SLM provides for rapid loading of office images and updates. It

consists of a 600 megabyte hard disk and a 150 megabyte high-speed streaming tape drive to permit fast memory loading. There are two SLMs . Each is directly

connected to its corresponding CM.

The Intelligent Cellular Peripheral (ICP) is a dual shelf (ICP 0 and ICP 1) peripheral designed to provide the necessary functions for supporting a call

processing interface for cell site communications. The dual shelves operate in hot standby mode. That is, one shelf is active, providing the necessary processing and control functions, while the adjacent shelf is in hot standby mode, able to take over if a fault occurs on the active shelf. The call processing interface handles all signaling between the DMS-MTX and the

NAP/SLSS to support incoming and outgoing calls, and intersystem handoff. The ICP interface to the NAP/SLSS is done via cell site emulation. The satellite

resources (GC, SLSS, NAP, CU) emulate cell site(s) for the ICP. Each "cell site" communicates to the ICP via LAPD communications on a DS0 of the Tl connecting the satellite resources to the GWS. The ICP views the satellite resources as multiple analog cell sites.

The communicating to and from a cell site is done using a Layer 3 proprietary Northern Telecom cell site protocol. In addition to providing the necessary mechanism to allow the MSS to interconnect to the GWS and provide call processing services, the emulation of a cell site presents some situations that are

applicable to cellular telecommunications, but do not have any meaning to satellite telecommunications.

These situations are handled by the SLSS and NAP in a manner to satisfy the ICP protocol.

The following list outlines the hardware support that an ICP provides for connecting to the MSS.

• 10 Tls per ICP

• 240 DSO Channels

• 2 DSOs per Cell Site used for LAP-D Communication (1 Active, 1 Standby)

• 118 DSO Voice Connections per Cell Site (Maximum)

The ICP connects to the DMS-MTX via one DS 512 fiber link. The DMS-MTX can accommodate seven ICPs providing 1512 channels between the GWS and the

NAP/SLSS.

The Digital Trunk Controller (DTC) is a dual shelf

(DTC 0 and DTC 1) peripheral designed to provide the necessary functions for supporting trunk terminations to the outside networks. The dual shelves operate in hot standby mode. That is, one shelf is active, providing the necessary processing and control

functions, while the adjacent shelf is in hot standby mode, able to take over if a fault occurs on the active shelf. The DMS-MTX will accommodate thirteen DTCs to provide for 255 T-1 connections. (150 CTN, 105 PSTN/PN - max configuration). The DTC provides the following:

• Tl trunks to process incoming and outgoing call processing (DID and DOT trunks)

• Tl trunks to provide an interface to private network PBXs.

• Tl trunks to Voice Mail systems (Option)

• Tl trunks for Intersystem Handoff voice connections to the CTN (AMSC)

• Tl trunks to PBX to provide support for

administration

• Tl trunks to a Channel Bank for four wire E&M connections

The DTC connects to the DMS-MTX via one DS512 fiber link. The DTC can support up to twenty Tls. This provides 480 channels per DTC.

The Link Peripheral Processor (LPP) in the DMS-MTX provides an interface to Northern SS7 networks to provide the following:

• CTN SS7 network to provide point to point IS-41 interface over an F-link to another SS7 CTN node.

• CTN SS7 network to provide IS-41 messaging interface to an STP over a standard A-link.

The LPP connects to the DMS-MTX via sixteen DS30 links. The Input/Output Controller (IOC) provides the interfaces for the microprocessor based Input/Output Device (IOD) controllers. The IOC relays messages to IOD controllers.

The IOC in the DMS-MTX provides the interface for the following devices:

• Maintenance and Administration Positions (MAP) -

The MAP is used for overall maintenance and

administration of the DMS office. The MAP is a

standard VT100 format that provides access to switch table sand configuration. • Printers - The printers connected to the IOC are utilized to dump log reports and operational

measurements to paper.

• Disk Drive Units (DDU) - The DDU consists of a disk drive and power converter card. The purpose of the DDU is to provide storage for CDRs, log files, and other switch output files.

• Magnetic Tape Drive (MTD) - The MTD is a 9-track tape unit used to store data for applications. These applications include OMs, trouble diagnostic data, CDRs, customer data modification, and office data modification.

• Device Independent Recording Package (DIRP) - This is part of the IOD subsystems and operates under the control of the IOC. The main purpose of DIRP is to redirect output from switch processes to output devices such as printers and disk drives. DIRP controls the data flow from originating subsystems such as CDR, OM, of JF, and the recording devices on which the data is to be stored.

• X.25 layer 2 and Layer 3 IS-41 to the CTN - The X.25 connections provided t the CTN provide the

carriage of IS41 signaling to and from other Mobile Switching Centers (MSC)s. This connection can operate at 9.6kbps, 19.2kbps, or 56kbps depending on the card and type of X.25 connection/modem.

• Call Detail Record (CDR) Interface - The CDR interface provides the mechanism for the transfer of billing records from the switch to a peripheral device at near real time. For the MSS this peripheral device is the Network Operations Center (NOC) .

• Dial up Connection Interface - The Dialup

Connection allows the transfer of switch data over a telephone line. These interfaces are commonly used as remote MAPs . • Operations and Maintenance Connections - The O&M interface is provided by a connection through the IOC to an external device for the transfer of Logs and OMs from the switch to a device for processing.

The DMS-MTX contains additional devices used for trunking. The MCAM cabinet type contains the following DMS-MTX devices:

• Package Trunk Module (PTM) - The PTM is a system peripheral module that encodes and multiplexes incoming speech from a maximum of 30 analog trunks into 8-bit pulse code modulation format. The PTM combines

information with internal and supervisory control signals for transmission at 2.56 mbs to the network.

• Service Trunk Module (STM) - The STM is a reduced size Maintenance Trunk Module (MTM) . The MTM primary function is to interface service, test, and maintenance circuits. Each STM operates independent of the other and functions as a separate peripheral module. The STM accepts analog trunks, digital service circuits, or both, and processes the signals to a common PCM format. One type of STM is the Digital Recorded Announcement Machine (DRAM) . The DRAM provides recorded

announcements that have been stored in digital format. The DRAM can provide fully digitized voice

announcements for up to thirty separate channels simultaneously. A fully configured DRAM can provide up to sixty-four separate announcements.

• Power Distribution panel (PDP) - The PDP performs the power source distribution for the DMS-MTX.

The DE-4E Smart Terminal is the chosen Channel Bank for CGS. This Smart Terminal is an intelligent

microprocessor based EMI compliant system designed to provide point to point private lines. The single-digroup DE-4E Smart Channel Bank is capable of housing up to 24 "service adaptive" channel units. The channel units are available for two wire or four wire circuits and various signaling including E&M type 1, 2 and 3.

The Timing Signal Generator (TSG) is used to derive system clocking for SS7 signaling. The TSG derives its timing from T-1s connected to a toll office with a stratum three or higher clock. The TSG then

distributes timing to the various components. Note that the TSG is only used when SS7 signaling is

required. The DCD-400 from Telecom Solutions is the chosen model for the GWS TSG.

When the TSG is not used to provide system

clocking, a standard clock card in the SNSE cabinet is used to distribute clocking to the DMS-MTX.

To provide the ability to patch T-1s from the DTC and ICP to various other pieces of hardware, Channel

Banks, MUXs, and MAPs for example, the MTX is equipped with two Digital Signal Crossconnection Patch Panel (DSX) patch panels, such as the DSX-29/56 model

manufactured by ACD Telecommunications. The patch panel provides the following:

• 56 connections total

• Wire-wrap rear cross-connects

• Horizontal and vertical rings

• Flush 3" or 4" mountings

• Jacks numbered A 1-28, B 1-28

• Red flashing LEDs

• Bantam jack monitoring and patching

The Main Distribution Frame (MDF) is the

demarcation point for four wire E&M trunks.

The GWS software and hardware will provide for the following Voice Service Features in addition to the basic call processing.

• Call Forwarding Unconditional - The GWS will control the forwarding of calls made to MT users that have activated this call forwarding feature. When this feature is activated, calls are forwarded to the CFU number without attempting to contact the MT user.

• Call Forwarding Busy - The GWS will control the forwarding of calls made to MT users that have

activated this call forwarding feature. When this feature is activated, incoming calls to a MT are forwarded if the MT is involved in another call. Note that the incoming call must be to the same MIN that the MT is currently using.

• Call Forwarding No Reply - The GWS will control the forwarding of calls made to MT users that have activated this call forwarding feature. When this feature is activated, incoming calls to a MT are forwarded if the MT either does not respond to the page request, or times out ringing.

• Call Waiting - The GWS will control this feature. If a MT user is involved in a call and receives another call to that MIN and has Call Waiting, the DMS-MTX puts the incoming call on hold and applies a 440Hz tone to the voiceband to notify the MT of the other call. If the MT user decides to toggle to the other call, the DMS-MTX connects the second call to the MT and puts the original call on hold.

• Conference Calling - The GWS will control this feature. If a MT user decides to add a third party to a call (the DMS-MTX supports a maximum of three parties in a call), the MTX puts the first call on hold, allocates a conference port and routes the second call. Once the MT user signals the MTX to conference the calls, the MTX connects all three parties together. If the MT who originated the first call was the originator of the conference, and he hands up, all parties are disconnected.

• Call Transfer - The GWS will control this

feature. If a MT was called by another party and wishes to transfer the call, the MTX puts the first call on hold and allocates a conference port and routes the second call. At this point there are three options for the MT.

- Option 1 - Hang up before the party answers. In this case the MTX will transfer the call.

- Option 2 - Wait for the other party to answer, talk and hang up without ever conferencing in the other party from the first call. At this time, the MTX will transfer the call.

- Option 3 - Wait for the other party to answer, conference in the other party. After conversing in a conference, hang up. At this time, the MTX will transfer the call.

• Call Forwarding Congestion - The GWS will control this feature. If the situation arises at the GWS where all of a particular trunk group is busy to or from a switch, the DMS-MTX has the capability to datafill a secondary route that will be used if the primary route is busy or out of service. There are two other

possible call forwarding scenarios that the switch addresses. First, if there are no channel units available for a particular call, the MTX will send the call to an announcement. Next, if there are channel units available, but no satellite frequencies, the MTX will either send the call to the page timeout

announcement, or reroute the call if the MT user has this feature activated for the particular MIN being called.

• Call Barring - The GWS will control part of this feature. The GWS will validate the MIN and ESN of a MT either via a lookup in the HLR or by communicating to the Home MSC of the MT via IS41. The GWS provides line options in the HLR to allow restrictions such as denied originations (DOR) , denied terminations (DTM) , or suspended service (RSUS, SUS) to be placed on MT users. • Operator Assistance - The GWS will control this feature. The DMS-MTX provides the ability to route calls that request operator services to a route that will send the call to an operator switch.

• Alternate Account Code Charging - The GWS

provides the ability for users to append a digit code (Account Code) at the end of the dialed digit string to differentiate calls made from different accounts. This string is not validated by the MTX and is strictly for customer billing clarification.

The call detail record (CDR) system is used to record comprehensive billing and other data on all calls. The CDR system accepts call information data from the DMS system. The data is then recorded on a tape, disk, or sent to the NOC by using the standard Multi-Network Protocol (MNP) protocol manufactured by Northern Telecom used to transfer CDR billing data from a DMS-MTX switch to a remote billing processor at near real-time .

The CDR's are recorded on the hard disk at the GWS and sent to the NOC by the X.25 (MNP) using a V.35 interface. There is a redundant X.25 link that can be enabled in the event of a failure of the primary path to the NOC. Since the CDRs are written to the hard disk at the GWS, the transfer on the backup link can begin at the point where the transfer failed in the case of a redundancy switch. This method insures that CDR's are not lost in the event of a failure in the primary path from the GWS to the NOC. The CDR fields are described in Table A.

The message protocol used for MNP contains the following Protocol Data Units (PDU) :

ACS-SFO: Access request message - Start file

outgoing This message contains the information necessary for the far end to begin establishment of a file transfer. (35 octets)

STS-ACK: Status message - Access request acknowledge This message is sent in response to the ACS-SFO message when the NOC accepts the billing file request. (3 octets)

CNT-PRT: Control message - Set device to print mode This message is sent to the NOC when the GWS is ready to transfer data. (2 octets)

CNT-RED: Control message - Set device to read mode This message is sent by the NOC to start the file transfer. (2 octets)

STS-EOB: Status message - End of block

This message contains the sequence number of the previous sent data block. This message is sent by the GWS to describe the data block just sent. (8 octets)

CNT-RNB: Status message - Request next block

This message contains the sequence number of the received data block. This indicates that the data blocks up to the sequence number were successfully received by the NOC. (6 octets)

STS-EOF: Status message - End of file

This message is sent by the GWS when the entire billing file is transferred. (2 octets)

STS-CPL: Status message - Access complete

This message is sent by both the GWS and the NOC to wrap up the current session. (2 octets) DATA: Application Data

This message is a 2K octet block of data, and is followed by the STS-EOB message. It contains billing information which is retrieved from the billing file on the disk.

The following describes the basic message flow between the GWS and the NOC for the transfer of CDRs via MNP.

Step 1: The GWS has a billing file ready to

transfer. The SVC of X.25 at layer 3 has been

established between the GWS and the NOC.

Step 2 : The protocol messages have been exchanged for startup, and both ends have recognized the billing file. At this point, the file transfer is ready to start.

Step 3 : The data blocks are sent from the GWS to the NOC. In the opposite direction, acknowledgement messages are sent back to the GWS to notify it of successful transfer of a data block. This example, shows a window size of one. This means that a CNT-RNB is expected before another data block is sent from the GWS. For applications with larger window sizes, i.e., greater than 1, the GWS will not wait for a NTR-RNB for a data block before transmitting the other data blocks contained in the window. The CNT-RNBs for each block are still expected, but can arrive back at the GWS in any order.

Step 4: When reaching the end of the billing file, the STS-EOF message is sent to the NOC to notify it of the completion of the file transfer. Subsequently, the STS-CPL message is exchanged to end the session.

Step 5: The GWS shuts down the X.25 SVC link between the GWS and the NOC.

Some MSS system users have voice communication requirements that are not met by MTS and Mobile Radio Service (MRS) . They need to communicate in a virtual network arrangement that allows each member of the group to hear what any other user is saying. Each member of the group can also talk when needed. The system behaves like a radio multi-party line. Public services and law enforcement agencies are typical users of this service, which is normally provided by either traditional terrestrial radio networks or by the more recent trunked radio systems. These trunked systems, generally in the 800-900 MHz band, provide groups of end users with virtual private systems by assigning frequencies to CUGs on a demand basis . The virtual network service is meant to be the satellite equivalent of terrestrial trunked systems ("trunking" for short), and could be pictured as a "Satellite Trunked Radio Service", or "Satellite Trunking".

The virtual network service provides the capability described in the previous paragraph in a cost effective manner :

as one shared satellite demand period circuit per virtual network is utilized rather than one circuit per mobile user, the cost per minute of a group conversation would be much less expensive to the owner of the group, and

as the call set-up time for one shared circuit per virtual network compared to an MRS multi -user conference set-up time is likely to be more

acceptable to a group end user/operator, who normally expects to be able to talk as soon as the handset/microphone is taken off-ho-k.

A virtual network is defined as a partition of METs and FESs within a control group having particular connectivity attributes. Each virtual network has a defined set of service features to which its users may subscribe as a whole or individually. As illustrated in FIG. 20, a virtual network is associated with a group of FESs and METs. It is possible for an FES to belong to a particular virtual network or be shared by multiple virtual networks. It is also possible for a MET to belong to a maximum of 16 different virtual networks. Interconnection between different virtual networks is supported by the MSS system.

The database files on the METs and the

communications nets of a subscribing organization comprise a Virtual Network (VN) within the MSS system, and is assigned a Virtual Network identification number. All of the METs in a VN may communicate with each other.

An overview of the MSS system with the VN service is illustrated in FIG. 21. FIG. 21 illustrates the basic concept and elements involved in establishment of communications and control in the virtual network system. METs access the system via one or more L-band beams. Each beam contains one or more signaling channels for network control and call establishment and a number of communications channels for provision of virtual network services to METs.

The L-band frequencies are translated to Ku-band frequencies by the satellite 12. The Network Control Center 14 is responsible for the real time allocation of channels to support virtual network calls. The base Feederlink Earth Station 16 is responsible for re-transmission on the outbound channel of the MET

transmissions received on the inbound channel, control of the virtual network call, and interfacing the virtual network call to terrestrial private networks.

Virtual network service is available to users in the virtual network group on subscription to MSS. A subscribing organization may comprise a number of METs grouped by their communication needs. A virtual private communication net is established for each of these groups or subgroups . The base FES 16 can interconnect the virtual network call to terrestrial private networks so that a dispatcher located within the private network can participate in the conversation. A dispatch facility may be directly connected to the base FES 16, or may use leased PSTN or dial-up access, or may use a Mobile Radio Service (MRSA) circuit. An example of a virtual network service subscribing organization with several communication virtual networks is depicted in FIG. 22.

The virtual network MET operates in a virtual network and receives voice transmissions from all other MET users in the same virtual network group, and the base FES. The MET supports virtual network service on a single demand period circuit per beam, which is shared by the entire group The MET requiring

communications will be given the virtual network (VN) ID for the net and since different VN groups may be necessary for different purposes, the MET may be given a number of different VN IDs.

VN IDs may represent organizational groups such as fleets or sub- fleets VN IDs may represent functional groups such as a command unit which draws on mobile users from more than one fleet or sub-fleet VN IDs may represent geographic configurations such as an east or west area, or both.

Virtual Network Configuration

Each GC receives from the NOC, via the NCC

Controller, the Virtual Network configuration database from each customer network. The database is processed and organized to support and optimize all real-time call processing accesses for Virtual Network attributes and configuration data. During operation the GC shall support the incremental addition to, deletion from, or modification to, the Virtual Network configuration database, under direction of the NOC. To support configuration changes each GC shall control the operating state of its Virtual Networks in accordance with NOC directives. Transitions between the following Virtual Network operational states shall be supported:

a. Inactive/initialized. Ready to become active.

b. Active - normal. Processing traffic normally.

c. Active - unloading. Blocking new calls and

servicing disconnects to unload traffic.

d. Active - unloaded. Blocking new calls; traffic has been unloaded.

The NCC Controller is able to display each GC Virtual Network configuration and status tables locally via the NCCTE man-machine interface, or to transmit Virtual Network configuration and status tables upon request to the NOC via the MSS Internetwork.

Virtual Network Call Status

These tables contain call status data for each Virtual Network:

a. Call data records:

i. Call Identifier

ii. FTIN

iii. RTIN

iv. MET supplied dial digits

v. Terrestrial network supplied dial digits vi. MET port id

vii. Service type (voice, data, fax and

expansion to new service types) viii. Connection type (MET to terrestrial, MET to

MET, terrestrial to MET.

ix. Control Group ID

x. Virtual Network

xi. Advanced features used

xii. FES Terminal

xiii. Circuit pool utilized. xiv. L-band beam accessed.

xv. Forward link Ku-Band frequency used.

xvi. Forward link L-Band frequency used.

xvii. Return link L-Band frequency used.

xviii. Return link Ku-Band frequency used.

xix. Forward link power level authorization. xx. Queueing flag.

xxi. Priority for queueing.

xxii. Date/time of access request.

xxiii. Date/time of channel assignment.

xxiv. Date/time of setup complete.

xxv. Date/time of channel release.

xxvi. Call clearing reason code,

b. Aggregate calls in progress.

c. Current call processing completion rat.e

d. Current call blocking rate.

Virtual Network Configuration Table

This table defines the configuration databases for each Virtual Network, served by the Control Group. The database provides a complete definition of each Virtual Network's service permissions, routing rules, and address screening constraints. This table also

contains the NOC assigned operating state for each Virtual Network - Inactive/Initialized, Active-Normal, Active-Unloading, Active-Unloaded. The GC supports foreground and background Virtual Network Configuration tables to facilitate the network configuration change procedures.

Virtual Network Functional Characteristics

This section describes the virtual networking capabilities offered by the MSS. Generally from a functional perspective, a virtual network involves membership rules, a dialing plan, and a set of dialing allowances and/or restrictions. Each MET is a member of at least one VN. A MET is optionally a member of up to 15 additional VNs . One VN of which a MET is a member be denoted as the default VN for that MET. MET VN membership(s) is provided on a subscription basis. Dual-mode METs (METs capable of both cellular and MSS operation) that are registered in the MSS shall constitute a specific VN denoted VN-C. No other METs is members of VN-C.

VN MET addresses are selected from blocks of numbers allocated from the North American PSTN. Since MET numbers are selected from the North American PSTN, and no number translation is performed, MET and PSTN/PN numbers are disjoint. A MET user has the capability to select, on a call-by-call basis, the specific VN within which he/she wishes to act; this VN is denoted the

"acting VN" . The MET user indicates the acting VN by an optional suffix. If no suffix is presented, the acting VN is the default VN defined for the MET. The MET must be a member of any VN selected by the suffix.

Within an acting VN:

a. MET-to-MET calls utilize 7-digit (NXX-XXXX) dialing, or 10-digit (NPA-NXX-XXXX) dialing. Other dialing plans for MET-to-MET calling may be offered as options.

b. MET-to-PSTN/PN calls utilize 10 digit dialing, international dialing and dialing access to operators, carriers, etc., as offered by the connected PSTN/PN.

All dialed numbers are subject to screening based on the VN rules and the screening associated with the individual MET. In VN-C (for dual -mode METs registered in the MSS) registered dual-mode METs shall use their usual PSTN number.

For each VN, it is possible to define call

screening (call barring) rules (restrictions and allowances) for every MET in the VN. Screening rules for MET originated calls are definable to govern the allowance of a call originating at every MET in the VN. Screening rules are definable to govern the acceptance of a call presented to every MET in the VN. In

addition to screening rules defined for all METs in the VN, screening rules are separately definable for individual METs within the VN.

For MET-originated calls, the following general rules are available based on the called number.

A MET-originated call may be permitted to:

a. Any MET number in the VN.

b. No MET number in the VN.

c. Any PSTN/PN number.

d. No PSTN number.

e. Only domestic US PSTN numbers.

f. Only PSTN numbers within NPAs on a specified NPA list.

g. No PSTN numbers within NPAs on a specified NPA list.

h. Only to MET and/or PSTN/PN numbers on a

specified list .

Order of application of these rules shall be as indicated by the decision tree in FIG. 23. For calls presented to METS, the following rules are available based on the call source (when available)

A MET-presented call may be permitted from:

a. Any MET number in the VN.

b. No MET number in the VN.

c. Any PSTN/PN number.

d. No PSTN/PN number.

If calling line identification presentation is available from the PSTN/PN, a MET-presented call may be permitted from:

e. Any domestic US PSTN number. f. Only PSTN numbers within NPAs on a specified NPA list.

g. No PSTN numbers within NPAs on a specified NPA list.

h. Only from MET and/or PSTN numbers on a

specified list.

Order of application of these rules are as

indicated by the decision tree in FIG. 23. Additional call screening rules may be provided. For example, a MET restricted from making any outgoing call is

restricted from Call Transfer since that feature involves outgoing call placement.

MET Features

This section provides a description of each feature available to MET users. Availability of a feature to a specific MET depends on the characteristics defined for the VN in which the MET is a member and the

characteristics defined for the individual MET.

Connected Line Identification Presentation (COLP) is a service that is offered to the calling MET to provide presentation of the connected MET's number (when the call is established) to the calling MET. The GWS is capable of providing at least 10 digits for MET-terminated calls and at least 15 digits for PSTN/PN-terminated calls to the calling MET.

COLP is provisioned on a subscription basis

collectively to each METs within the VN. COLP is withdrawn on request by the subscribing authority or by MSS for administrative reasons. COLP is active on subscription and inactive on withdrawal. COLP is automatically invoked by the GWS at call completion. When COLP is allowed and active, the GWS provides the calling MET with the connected MET VN number at call completion (answer) for all MET-originated incoming calls. When COLP or equivalent service is provided by the PSTN/PN, and the connected PSTN/PN number is provided by the PSTN/PN, the GWS provides the calling MET with the connected PSTN/PN number at call completion

(answer) for all PSTN/PN-completed calls. When COLP is allowed and active, the connected number is not

presented if:

a. The connected MET has COLR activated, or b. The connected number is not available from the PSTN/PN.

Assume that a user A has an established call with user B and transfers this call with user B to user C. If user A has activated COLP, user A receives B's number when user A evokes the normal call transfer procedure. If user C has activated COLP, user C receives B's number at the transfer of user B to user C. A conference controller who has COLP activated is presented with the connected party's number when that party is either part of the initial activation of the conference or is added to an existing conference.

If the connected party has activated Connected Line Identification Restriction the connected number is not presented to the calling party. If the incoming call from a MET with COLP activated has been forwarded, the number presented to the calling party is the number of the final "forwarded to" party.

Connected Line Identification Restriction (COLR) is a service that is offered to the connected MET to restrict presentation of the connected MET's number to the calling MET or to the PSTN/PN. COLR is provisioned on a subscription basis collectively to each MET in the VN and/or individually to METs within the VN. COLR is withdrawn on request by the subscribing authority or by MSS for administrative reasons. COLR is active on subscription and inactive on withdrawal. When COLR is allowed and active, the GWS does not provide the calling MET with the connected MET VN number for all MET-originated calls. When COLR is allowed and active, no connected MET number is provided to the PSTN/PN for any PSTN-to-MET calls.

Assume that a user A has an established call with user B and transfers this call with user B to user C. If user B has activated COLR, user A receives B's number when user A evokes the normal call transfer procedure. If user B has activated COLP, user C receives B's number at the transfer of user B to user C. If potential conferees have COLR activated, the conference controller is not presented with the

connected party's number when that party is either part of the initial activation of the conference or is added to an existing conference.

If the connected party has activated Connected Line Identification Restriction (COLR), the connected number is not presented to the calling party If the incoming call from a MET with COLP activated has been forwarded, and the "forwarded to party has COLR activated, the "forwarded to" party's number is not presented to the calling party.

The intent of sub-addressing is to allow the identification of separate ports and connected device that may be part of a MET. Examples include voice, facsimile and data ports/devices Each usable port on a MET shall be assigned an VN number. The implication is that a MET port that is physically present but does not have an assigned number cannot be used. In the following, the term "MET sub-address(s)" is used to describe one or all of the set of (complete) VN numbers assigned to the ports of a given MET.

The general model adapted for the subaddressing description is a PBX telephone with multiple extensions associated with it. For example, a result of this model is that the various MET subaddresses can be forwarded separately - - this (and other) results are appropriate for multi-device (multi -media) METs.

Subaddressing is provisioned and number assigned on a subscription basis individually to METs within the VN. Subaddresses is withdrawn on request by the subscribing authority or by MSS for administrative reasons. Subaddressing is active on subscription and inactive on withdrawal.

Features are subscribed to and activated for each

MET subaddress separately (e.g., forwarding). It is assumed that some features (e.g., Forwarding, Hold, Transfer) will have utility for non-voice calls.

Others are precluded by the nature of the communication devices (e.g., Conferencing, Call Waiting). For call completion purposes, a MET is considered busy if any MET subaddress is busy. Forwarding applies to each MET subaddress separately. However, for Call Forwarding Busy, the busy state applies as in 2 above.

Call Forwarding No Reply is interpreted to apply to a MET port that has a MET subaddress assigned but no device connected. In-channel Call Waiting indication is applicable to voice ports/devices only. Number Identification features shall apply to each MET subaddress separately. For example, CLIP can be activated for some MET subaddresses and not others. Call screening rules shall be definable for each subaddress separately.

The Call Transfer (CT) feature enables a MET user (the "served user" or "A") to transform an established call into a new call between the other party on the established call (user "B") and a third party (user "C"). The "normal" Call Transfer procedure is offered as a feature to MET users. The GWS may offer an additional "single step" Call Transfer procedure (see below) to MET users. "Normal" call transfer (sometimes called "screened transfer") establishes a call between the served user and the third party that may be subsequently

transformed into a call between the other party and the third party. Optionally, the GWS may offer "single step" ("unscreened") transfer where the transfer occurs without an established call between the served user and the third party.

CT is provisioned on a subscription basis

collectively to each MET in the VN and/or individually to METs within the VN . CT is withdrawn on request by the subscribing authority or by MSS for administrative reasons. Each of the CT types offered is subscribed to separately. The "normal" call transfer procedure shall normally operate as follows:

a. An established call exists between A and B.

b. A invokes the "normal" CT procedure, providing the number for C.

c. B shall be placed on hold and a call shall be established between A and C.

d. During the established call, A invokes

completion of the "normal" CT procedure. e. B shall be connected to C; connection are

removed between A and the other parties. If, during the "normal" CT procedure, the call to C cannot be established, A shall be able to retrieve the connection to B. The "single step" call transfer procedure, if offered, normally operates as follows: a. An established call exists between A and B. b. A invokes the "single step" transfer procedure, providing the number for C.

c. A call is established between B and C. A is disconnected.

After the "single step" CT procedure has been invoked, B is considered the originating party of the attempted call to C; for example, B is informed of alerting at C and, if the call to C cannot be completed, B is

informed.

Call forwarding allows the served or "forwarding" user to direct the GWS to send incoming calls to the served MET number to other numbers under specific conditions. Call Forwarding Unconditional (CFU) allows the forwarding user to direct the GWS to send all incoming calls to another number. Call Forwarding Busy (CFB) allows the forwarding user to direct the GWS to send incoming calls to another number if the forwarding user's MET is in the "busy" state (establishing a call or involved in an established call, on hold or invoking a feature).

Call Forwarding Congestion (CFC) allows the GWS to send incoming calls to a recorded announcement if the forwarding user's MET cannot be connected to MSS congestion. Call Forwarding No Reply (CFNR) allows the forwarding user to direct the GWS to send incoming calls to another number if the forwarding user doe not reply within a subscribed time interval.

Forwarding is provisioned on a subscription basis collectively to each MET in the VN and/or individually to METs within the VN . Forwarding is withdrawn on request by the subscribing authority or by MSS for administrative reasons. Each of the forwarding types offered is subscribed to separately. MSS may offer forwarding in "packages" containing one or more

forwarding types.

The served user is able to activate each of the forwarding types offered separately. Activation of forwarding requires the served user to supply the forwarded-to number. The GWS validates the forwardedto number to the extent possible before activating forwarding. When forwarding is active and forwarding conditions are met, forwarding is automatically invoked; incoming calls to the served user's MET is forwarded without being offered to the served user's MET.

A configurable limit is provided on the maximum number of forwarding invocations that result from a single original call. This is intended to prevent "infinite forwarding." The GWS may provide

notification to the served user's MET when forwarding takes place. When a call is forwarded, the forwarded-to MET is provided an indication that the incoming call is offered as a result of forwarding. The GWS provides the originally called number and the condition for the last forwarding operation to the forwarded- to MET.

The GWS provides notification to the calling user that the call has been forwarded. The GWS provides the capability for the served user to review the MET's forwarding status. The forwarding user's MET

optionally receives an indication that an incoming call has been forwarded. This may involve a separate subscribed service.

Call waiting (CW) is a service that is offered to a called MET that provides that MET indication of an incoming call, if busy. If it can be determined that the active call is a voice call, in-channel indication (tone) is provided. Otherwise, in-channel indication is not be provided. The number of waiting calls at a busy MET is limited to one. Additional incoming calls receive busy indication.

CW is provisioned on a subscription basis

collectively to each MET in the VN and/or individually to METs within the VN. CW is withdrawn on request by the subscribing authority or by MSS for administrative reasons. CW is active on subscription and inactive on withdrawal. A procedure is provided to allow

activation or inactivation on a call-by-call basis. CW is invoked by the GWS automatically when a call is presented to a busy MET unless a waiting call exists at that MET. The MSS network may not be aware of the state where the MET users is entering digits for a call but has not yet invoked "send." During this state call attempts may ring rather than invoke CW or busy

forwarding. Call Forwarding Unconditional takes precedence over CW. CW takes precedence over CFB . CW is presented if the called MET has CFNR activated.

The Call Hold (CH) service allows a served MET user to interrupt an existing active call and subsequently resume (retrieve) the active call. The bearer channel remains assigned to the served user to allow the origination or termination of other calls. The

retrieve re-establishes the original (held) call on the bearer channel. CH is provisioned on a subscription basis collectively to each MET in the VN and/or

individually to METs within the VN CH is withdrawn on request by the subscribing authority or by MSS for administrative reasons Call Hold is invoked by the served MET user by use of a control procedure

The served user has the capability to invoke or hold any time after a call has been answered and before call clearing has begun Call Hold allows either MET or both METs in an active call to invoke Call Hold That is, it is possible for each party to have the other on hold. If a user invokes hold while held and makes an additional call, a new channel will be

assigned.

Provision shall be made for providing the held MET user with in-channel indication ("comfort" tone, music, etc.) that the held state persists. This indication will also inform the user who retrieves a held call that has been placed on hold by the other party. If a MET becomes idle with a call on Hold, an indication is provided to that MET that the call remains on Hold. Conference Calling (CONF) is a service that

provides the served MET user the capability to

establish simultaneous communications with more than two and up to five parties. Since MET voice traffic is presented to the GWS in a packetized, compressed encoding, it is not required that the GWS provide the capability to conference more than one MET. Thus, GWS provides the capability for conferencing among a single MET and up to five PSTN/PN parties.

CONF is provisioned on a subscription basis

collectively to each MET in the VN and/or individually to METs within the VN. CONF is withdrawn on request by the subscribing authority or by MSS for administrative reasons. CONF is active on subscription.

CONF is invoked by the served MET user by use of a control procedure. The served user has the capability to request the conference as a new call or request that the conference be based on existing held calls. The served user has the capability to include the maximum number of conferees in the conference request or to accept a pre-defined default. Upon completion of the conference request, a conference is established among the served MET and the other parties.

After the initial conference establishment, the served user (the conference controller) has access to the following party management functions:

a. Add new party - - the conference controller has the capability to add a held call or establish a new call which may be added to the conference.

b. Drop party - - the conference controller has the

capability to remove conferees from the conference. If the conferee is not explicitly identified, the last party added is removed. If, after the party is dropped, a single conferee remains, the GWS may establish a two-party call. c. Split party - - the conference controller has the capability to remove a specified party from the conference and establish an active (two-party) call with the specified party. From the perspective of the conference controller, the conference is on

Hold. The conference controller has the capability to resume the conference after a split (i.e., return both parties to the conference).

A mechanism for supplying Conferee IDs for

conference management features above (e.g., dropping a specific conferee) is provided. The conference

controller has the capability to disconnect the

conference. All conferees and the conference

controller are dropped and the conference resource (bridge) is released.

Alternate Account Charging (AAC) allows a MET user to charge a call to an account other than the usual or default account. Alternate account charging provides the MET user the capability to supply an Alternate Account Number during call setup request. GWS records the Alternate Account number in the CDR. GWS is not required to verify or otherwise validate the Alternate Account Number.

AAC is provisioned on a subscription basis

collectively to each MET in the VN and/or individually to METs within the VN. AAC is withdrawn on request by the subscribing authority or by MSS for administrative reasons. AAC is activated upon subscription. AAC is optionally invoked by the MET user at call setup request. The invocation includes the Alternate Account Number.

Call Queueing and Priority (CQP) are intended to be applied to MET-originated calls in the event of MSS network congestion. Note that the management of satellite resources is a function of the MSS Network Control Center (NCC) and not a function of the GWS. However, upon notification of satellite resource congestion by the NCC (via the SLSS), the GWS queues calls affected by that congestion. Similarly, upon notification by the NCC that congestion no longer exists, the GWS attempts to service queued calls as detailed below.

Priority and queueing are not intended to be applied in the event of a buy MET. Call Priority and Queuing may also occur as a result of congestion for

PSTN/PN access. Congestion of MSS satellite signalling channels occurs as well as traffic channel congestion. Signaling access queueing occurs external to the GWS.

GWS supports traffic access queueing for MET-originated calls when traffic congestion is indicated by MSS. Determination of satellite congestion

conditions is not a function of the GWS. GWS supports traffic access queueing for MET-originated calls when PSTN/PN access congestion exists. Traffic access priority is assignable to a VN and to individual METs. Call setup requests are queued under congestion

conditions and are processed first-in, first-out within individual priorities.

CQP is provisioned on a subscription basis

collectively to each MET in the VN and/or individually to METs within the VN. CQP is withdrawn on request by the subscribing authority or by MSS for administrative reasons. Specification of priority accompanies

subscription. CPQ is active on subscription. If CQP is not subscribed to, calls receive a congestion indication but will not be queued.

CQP is invoked automatically by GWS upon indication of satellite congestion by the SLSS or detection of PSTN/PN access congestion by GWS. If CPQ is invoked, GWS provides the calling MET indication of congestion and queueing. When congestion is relived, GWS serves queued calls according to priority as follows:

a. Originating a call to the MET that originated the queued call.

b. If this call is successful, GWS shall execute call setup procedures for the queued call.

Virtual Network Manager

Virtual Network Manager controls user access to a designated virtual network and its service features, provides communication circuits among member users on a call-by-call or full period basis, and manages a customer virtual network. The Virtual Network database entries for a given network shall specify the type of services, network features and call routing options that are available for use by member METs and FESs.

Virtual Network Managers interact only with member METs an FESs.

The Virtual Network Management function interfaces with the Group Resource Management function and the Network Access processing function to carry out its responsibilities to receive call requests and issue satellite circuit assignments, to request, receive and return satellite circuits from/to the CG circuit pool, to return preempted circuits, and to transmit call records following each call cleardown.

To provide service connections for customers, Virtual Network Management provides functions for connection period control, call processing, call routing, circuit configuration, address screening, emergency preemption, and resource utilization

auditing. The Virtual Network Manager maintains a record of which GC managed features are active.

Features which are activated by subscription are active and perform the actions specified below for each active feature. The GC supports VN configurations for virtual network service consisting of a set of METs, each with a MET Database File, and a set of virtual network communication groups, each assigned a VN ID with a VΝ ID Database File. The GC performs VΝ Management for each call request. Each GC supports multiple customer virtual network configurations in accordance with the virtual network definition.

As each MET or FES originated access request is received, the GC identifies which Virtual Network is being accessed, according to the procedures specified below, and utilizes the associated Virtual Network database and the Customer Configuration database to process and service the request. Virtual Network management is performed for each call request in accordance with the call processing specifications.

The GC supports the provision of advanced service features to MET When Call Forwarding or Call Waiting has been activated the following Virtual Network call processing requirements for basic service shall be superseded at the appropriate points in the protocols.

The following describes the Virtual Network process requirements in the context of FIG. 24 which is a more detailed illustration of the NCC terminal equipment. MET originated access requests received by the Network Access Processor are routed to the GC to which the receiving MET-SR signaling channel has been assigned by the NCC Controller. The GC takes the following actions based on the GC operational state.

In the Active - Normal state the GC examines the "Access Request" message to determine whether a Virtual Network identifier has been transmitted by the MET along with the dial digits. If a Virtual Network identifier has not been included in the request, the GC determines the METs default Virtual Network from the Customer Configuration database. If a particular

Virtual Network has been requested, the GC utilizes the customer Configuration database to convert the logical Virtual Network identifier of the message to the internal Virtual network identifier. The GC then takes the following actions based o the Virtual Network operational state.

FES originated channel requests received by the Network Access Processor are routed to the NCC

Controller, based on the message destination address. FESs will address channel requests to the NCC

Controller so the MET Control Group membership can be determined. The NCC Controller accesses the Customer Configuration database, using the MET telephone number dial digits included in the FES "Channel Request" message, and determines the identity of the GC to which the MET belongs. The NCC Controller then forwards the message to the identified GC.. The GC shall take the actions as specified above based on the GC operational state.

In the Active - Normal state the GC accesses the Customer Configuration database, using the MET

telephone number dial digits included in the FES

"Channel Requests" message, and determines the identity of the Virtual Network which is being accessed. The GC then takes the actions specified above based on the Virtual Network operational state.

Whenever the NCC Controller determines that the GC cannot be successfully identified in the databases using received access signaling data, the access request is denied. Whenever the GC determines that a called or calling MET is registered but the Virtual Network cannot be successfully identified in the databases using received access signaling data, the access request is denied. When calls are so denied, a "Call Failure" message with the cause set to "Service not Subscribed" is sent to the requesting MET or FES, and the call data record is terminated with the cause indicated.

Upon successful identification of the Virtual

Network serving the access request, the GC processes calls, using the associated Virtual Network database, in accordance with the Virtual Network management requirements specified in the following sections.

Whenever a call record for an access request is

terminated for any reason, the appropriate Virtual Network performance statistic is updated.

Access request processing consists of call

screening actions using the Customer Configuration and Virtual Network databases, and the MET Status Table, to determine whether the requested service is a valid subscribed service for the MET and the Virtual Network, and whether the MET status is in a call state

compatible with the access request. In performances of MTS access request processing, the GC processes dial digits for PSTN users in accordance wit the PSTN numbering plan. In performance of MRS access request processing the GC accommodates independent numbering plans, using fewer dial digits than the PSTN plans, which will be utilized by each private Virtual Network.

Upon each MET or FES access request, the GC

evaluates the security authentication history for the associated MET. If a configurable number of

authentication failures have occurred within a

configurable time period from the time of access, the call is denied.

MET to Terrestrial Network Connection Requests

In processing MET originated call requests, the GC receives MET "Access Request" and "Additional Digits" messages, and shall transmit "Additional Digits Request" and/or "Call Failure messages when required. Upon receiving a MET "Access Request" the GC accesses the MET Status Table using the RTIN to verify the calling MET is in the "Operational" state and whether the MET is currently engaged in a call. The identity of the MET-SR channel receiving the request is used by the GC to verify whether the MET is currently logged on to correct L-Band beam as indicated in the MET Status Table.

Log-on errors result in a PVT for the MET with the event and results sent to the NOC and noted as

anomalous events. When the PVT is successful the MET is logged on to the associated beam. If the MET is not in the "Operational" state the GC terminates the call record and sends a call failure message to the MET with the reason set to "Services not Available". If the MET is operational, the GC accesses the MET Status Table to evaluate the current MET call state.

If the MET call state indicates the GC is currently awaiting circuits or a MET call announcement response, for a prior FES channel request, the GC shall abandon the prior FES request in favor of the new MET access request, terminate the call record with the reason set to "Glare" and send a call failure to the FES with the cause set to "MET Busy" . The GC shall proceed to process the MET "Access Request" as further described in this subsection.

If the MET state indicates the MET is engaged in a call-in-process, the reason is declared as an anomalous condition, the MET is sent a call failure message with "Network Busy" as the cause and the current call record is terminated with "Calling MET Busy - Anomaly" as the reason. The GC then immediately initiates a call auditing action to resolve the anomalous condition existing for the prior call. This action will clear the MET status and network resources so that subsequent service requests by the MET will be accommodated.

When a requesting MET is operational, and in the "MET Idle" call state, the GC collects additional dial digits as necessary, access the Control Group Customer Configuration data base and determine, based on the destination dial digits, whether the called destination is a MET user. If the destination is not identified in the Customer Configuration database as a MET user the GC declares the destination to be a terrestrial user. The GC accesses the operative Virtual Network

Configuration database and performs the following

Virtual Network service permission and address

screening checks :

a. The type of service requested (voice/2.4kbps

data/4.8kbps data/fax/alternate voice-data) is supported by the Virtual Network.

b. If the Virtual Network is configured with an

explicit set of terrestrial user member telephone numbers, and the destination telephone number is included in the member list, then the call is permitted .

c. Outgoing calls permitted.

d. MET to terrestrial network calls permitted.

e. International calls permitted.

f. Calls to the specific destination NPA are

permitted.

If the Virtual Network address screening and service permission checks pass, the GC accesses the Customer Configuration database using the RTIN and the

destination dial digits, and perform the following MET address screening and service permission checks:

a. The type of service requested (voice/2.4kbps

data/4.8kbpsdata/fax/alternate voice-data) is authorized for the MET. b. Outgoing calls permitted.

c. MET to terrestrial network calls permitted.

d. International calls permitted.

e. Calls to the specific destination NPA are

permitted.

f . If the MET is part of a VN group, the destination telephone number is a VN group member.

If all MET and Virtual Network address screening and service permission routing checks are successful, the GC updates the call record with the appropriate data and perform the call routing process. If a MET or Virtual Network address screening check or service permission check is unsuccessful, the GC terminates the call record upon finding the first check failure, and sends the MET a call failure message with the cause indicated as "Service not Subscribed". The call record encodes the specific failed check resulting in

termination.

Terrestrial Network to MET Connection Requests

In processing terrestrial network originated call requests, the GC receives FES "Channel Request"

messages, and transmits "Call Failure" messages.

Terrestrial network access requests are preprocessed by the NOC Controller to identify the GC serving the called MET. Upon receiving a FES "Channel Request," the GC first evaluates the channel request message to determine whether this request is for the FES-to-destination MET connection of a MET to MET call.

If the request is not for a MET to MET connection, the GC accesses the MET Status Table, using access data provided by the NCC Controller, to verify the called MET is in the "Operational" state and whether the MET is currently engaged in a call-in-progress. If the MET is not in the "Operational" state, the GC terminates the call record and sends a call failure message to the FES with the reason set to "Service not Available". If the MET is operational and the MET call state is any state other than idle, the GC terminates the call record and sends a call failure message to the FES with the cause set to "MET Destination Busy"

If the MET is operational and not currently engaged in an active call state, the GC accesses the MET Status Table and evaluates the access event history data for recent unsuccessful call announcements. If there have been a configurable number of unsuccessful call

announcements within a configurable time limit, from the current time, the GC sends a call failure message to the FES with the reason set to "MET Destination Not Available". The call record is terminated with "Excess MET Pages" as the reason.

When the called MET is operational, not engaged in an active call state, and an acceptable number of unsuccessful call announcements have been placed to the MET, the GC accesses the operative Virtual Network Configuration database and perform Virtual Network address screening and service permission checks:

a. The type of service indicated by the MET

destination port (voice/2.4kbps data/4.8kbps data/fax/alternate voice-data) is permitted.

b. Incoming calls permitted.

c. Terrestrial network to MET calls permitted.

d. International calls are permitted (if the calling number is provided - otherwise connection is permitted by default).

e. The calling NPA is permitted (if NPA restrictions apply and the calling number is provided - otherwise connection is permitted by default).

f. If the MET is part of a closed user group (CUG), and the origination telephone number is both provided and recognized as a CUG member, then the call is permitted. If the calling number is not provided the connection is permitted by default.

If all MET and Virtual Network address screening and service permission routing checks are successful, the GC updates the call record with the appropriate data and perform the call routing process. If an MET or Virtual Network address screening and service

permission routing check is unsuccessful, the GC terminates the call record upon finding the first check failure, and sends the FES a call failure message with the cause indicated as "Service not Subscribed". The call record encodes the specific failed check resulting in termination.

MET to MET Connection Requests for Originating MET

If the destination is identified by the dial digits as a MET user, the GC accesses the Customer

Configuration database and determines if the

destination MET is subscribed with membership in the Virtual Network being accessed by the origination MET. If the origination and destination METs are members of the Virtual Network being accessed by the origination MET, the GC performs Virtual Network service permission and address screening checks for the destination MET using its Virtual Network Configuration databases.

After identifying the proper Virtual Network database((s) the GC accesses the MET Status Table and verify the destination MET is operational and not engaged in an active call state. If the destination MET is not operational the GC terminates the call record indicating "Destination MET not Available" . If the destination MET is in any call state other than idle, the GC terminates the call record indicating "Destination MET Busy", and the originating MET a call failure message with the cause indicated as

"Destination MET Busy".

If the destination MET is operational and idle, the GC sets a MET to MET call pending flag in the

destination MET status entry of the MET Status Table, accesses the MET Virtual Network Configuration

database (s) and performs the following Virtual Network address screening and service permission checks: a. The type of service requested (voice/2.4kbps

data/4.8kbps data/fax/alternate voice-data) is supported by the origination and destination

Virtual Networks.

b. MET to MET calls permitted.

c. Incoming calls permitted for the destination

Virtual Network

d. Outgoing calls permitted for the originating

Virtual Network.

e. Calls to any Virtual Network permitted by the

origination Virtual Network.

f. Calls to selected Virtual Networks permitted and the destination Virtual Network is in the permitted set.

If the Virtual Network service permission and address screening checks pass, the GC accesses the Customer Configuration database using the FTIN of the

origination and destination METs and performs the following MET address screening and service permission checks for the originating MET:

a. The type of service requested (voice/2.4kbps

data/4.8kbps data/fax/alternate voice-data) is authorized for the MET.

b. Outgoing calls permitted.

c. MET to MET calls permitted.

d. Calls to any Virtual Network permitted. e. Calls to selected Virtual Networks permitted and the destination Virtual Network is in the permitted set.

If the originating MET address screening and service permission checks pass, the GC performs the following

MET address screening and service permission checks for the destination MET:

a. The type of service requested (voice/2.4kbps

data/4.8kbps data/fax/alternate voice-data) is authorized for the MET.

b. Incoming calls permitted.

c. MET to MET calls permitted.

If all MET and Virtual Network address screening and service permission routing checks are successful, the GC updates the call record with the appropriate data and performs the call routing process. If an MET or Virtual Network address screening check or service permission check is unsuccessful, the GC terminates the call record upon finding the first check failure, and sends the MET a call failure message with the cause indicated as "Service not Subscribed". The call record encodes the specific failed check resulting in

termination.

MET to MET Connection Requests for Destination MET

Upon receiving a FES "Channel Request" that

indicates a FES-to-destination MET connection is being requested for a MET to MET call, the GC generates a separate call record for the Destination MET using the "Call Identifier" previously assigned during the originating MET call setup and provided in the request message. The call record includes MET ID data needed to complete the connection to the destination MET. The GC proceeds to route the call. Call Routing

When a GC successfully completes MET and Virtual Network address screening and service permission checks for access requests, the GC attempts to route the call using the routing rules and the Virtual Network Routing database. The routing process selects:

a. The FES Terminal Equipment that will support a MET to terrestrial network call, or

b. The FES Terminal Equipment and destination MET port that will support a MET to MET call, or c. The MET port that will support a terrestrial network to MET call.

The GC reports both MTS and MRS routing configurations. The GC accommodates, in any proportion, different routing rules for each member of a set of individual

Virtual Networks and accommodates common routing rules for selected sets of one or more Virtual Networks.

MET to Terrestrial Connection Routing

To route a MET call to the terrestrial network, the GC accesses the Virtual Network Routing database and selects the FES Terminal Equipment based upon the destination dial digits. Each MTS Virtual Network Routing database is configured such that a variable number of the first n dial digits are processed to select the FES Gateway. The first n dial digits are comprised of the following:

a. Domestic call or destination country code for international calls - [x] digits.

b. The destination NPA - 3 digits.

c. The local exchange within the NPA - 3 digits.

For MTS it is possible to associate each set of 'n' dial digits with an ordered set of FES Gateway entries. The FESs is arranged in the order of preference for routing. The number of FES Gateway entries ranges from 1 to 7. Each MRS Virtual Network Routing database is configured such that a specific range of numbers in the associated private numbering plan are processed to select a FRS Base Station. The dial digit ranges differentiate which FES base station is to be used. Each MRS dial digit number range is associated to an ordered set of FES base station entries. The FESs is arranged in the order of preference for routing. The number of numbering plan ranges are from 1 to 16 and the number of FES Base Station entries range from 1 to 3.

Once the GC has identified the routing FES entry set, it accesses the FES Status Table and FES Resource Pool for the most preferred FES It then determines that FES's network availability and the availability of its communication and terrestrial interface resources to support the call. If the preferred FES is available to the network, the GC allocates communication and terrestrial interface resources from the pool for the call being routed. FES resources are allocated based on the specific service type requested by the MET.

If the preferred FES is unavailable or the

communication or terrestrial interface resources are insufficient to support the call, the GC accesses the Customer Configuration and virtual Network

Configuration databases to determine whether both the MET and Virtual Network are authorized for alternate FES routing or fixed FES routing. If fixed FES routing is required, the GC terminates the call record

indicating "FES not Available" and sends the MET a call failure message with the cause set to "Network Busy".

If the preferred FES is unavailable or

communication or terrestrial interface resources are sufficient to support the call, and alternate FES routing is authorized for both the MET and the Virtual Network, the GC sequentially repeats the procedure above for each FES in the set, in descending order of routing preference, until an available FES is

identified with sufficient resources to support the call.

When an available FES with sufficient communication and terrestrial interface resources is identified, either under alternate routing or fixed routing

procedures, the GC proceeds to allocate satellite circuits to the call. The call record is updated to show the FES selected and whether the alternate or fixed process was used. If alternate FES routing is authorized but an available FES with sufficient

communication and terrestrial interface resources cannot be identified within the routing set, the GC terminates the call record indicating "FES not

Available or Insufficient FES Resources", as

appropriate, and sends the MET a call failure message with the cause set to "Network Busy"

In the event the Virtual Network Routing Table does not include any routing entries for the 'n' dial digits included in the request message, the GC terminates the call record indicating "Routing not Provided" and sends the MET a call failure message with the cause set to "Service not Subscribed". Terrestrial to MET Connection Routing

To route a terrestrial network to MET call, the GC accesses the Customer Configuration database and identifies the MET port that is associated with the MET's destination telephone number received in the channel access request message. The GC updates the FES Communication and Terrestrial Interface Status tables to reflect the resource allocation made by the calling FES prior to signaling the channel request for this call. The GC proceeds to allocate satellite circuits to the call and updates the call record to show the destination MET port ID selected.

MET to MET Connection Routing for Originating MET

To route a MET call to another MET, the GC accesses the Virtual Network Routing database and selects an FES Terminal Equipment from an ordered set of FESs that have been designated to service MET to MET calls.

Alternate routing is assumed automatically when more than 1 FES is included in the ordered set. The FESs are arranged in the order of preference for routing. The number of FES entries ranges from 1 to 7.

Once the GC has identified the routing FES entry set, it accesses the FES Status Table for the most preferred FES, and determines the FES's network

availability and the availability of its communication and terrestrial interface resources to support the call. If the preferred FES is available to the

network, the GC allocates MET to MET communication resources from the pool for the call being routed. FES resources are allocatable based on the specific service type requested by the MET.

If the preferred FES is unavailable or

communication resources are insufficient to support the call, the GC sequentially repeats the procedure above for each FES in the set, in descending order of routing preference, until an available FES is identified with sufficient resources to support the call. When an available FES with sufficient communication resources is identified, the GC proceeds to allocate satellite circuits for the originating MET connection. The call record is updated to show the FES selected. Subsequent FES processing generates a channel request for the FES-to-destination MET connection.

If an available FES with sufficient communication resources cannot be identified within the routing set, the GC terminates the call record indicating "FES not Available or Insufficient FES Resources", as

appropriate, and sends the MET a call failure message with the cause set to "Network Busy". MET to MET Connection Routing for Destination MET

To route the FES-to-destination MET connection for a MET to MET call, the GC proceeds to allocate circuits for the destination MT connection as specified in the MET to MET Connection Routing for Originating MET

Section.

Satellite Trunk Circuit Management

Only when all MET and Virtual Network service permission and connectivity checks for an access request have passed and network routing facilities have been determined available and reserved, the GC selects the required forward and return link trunk circuit frequencies and the FES forward link power level to service the call.

Each GC manages satellite trunk circuit resources using circuit pools. Channel center frequencies are identified in accordance with the separate L-Band and Ku-Band conventlons.

Circuit Allocation

The GC accesses the Customer Configuration database to determine the required circuit configuration for the MET port which is being accessed by the call. The database indicates the bandwidth required for the forward and return links, the minimum MET frequency tuning increment, and the FES forward link power level authorization. For MET to MET connections, the GC identifies forward and return link circuit

configurations for both the originating MET and destination MET and the following circuit and power allocation processing are performed for both METs.

The GC accesses the origination Virtual Network Configuration database to determine the connectivity period class authorized: demand period - free pool, demand period - reserved pool, or full period. The GC accesses the MET Status Table to identify the L-Band beam to which the MET is currently logged on. The GC then attempts to allocate the required circuit from the proper frequency pool, based on connectivity class and L-Band beam requirement.

The GC searches the pool to identify unused

frequencies containing continuous spectrum sufficient to provide the MET channel bandwidth requirement . The GC determines each resulting channel center frequency for inclusion in subsequent "Channel Assignment" messages. If the required circuits are available, the authorized forward link power level is retrieved from the Customer Configuration database for the associated MET port and the FES nominal EIRP retrieves form the FES Configuration Table.

Satellite Trunked Circuit Queuing

When queuing is enabled for MET originated calls, and the requested circuit pool bandwidth or power resources are not immediately available, the GC

accesses the Customer Configuration database to

identify the MET priority associated with the Virtual network being accessed. The circuit request is then entered into the tail of the queuing system which is structured with separate queuing sets for each L-Band beam being served by the GC . The individual queues within each L-band beam queue set is allocated to each MET priority level. Call Setup Processing

When all MET and Virtual Network service permission and connectivity checks for an access request have passed, network routing facilities have been determined available and satellite trunk circuits have been secured from the pool, the GC proceeds to the call setup procedure.

Off-Line NCC Virtual Network Updating

Each GC updates its counterpart GC in the Off-line NCC upon each transition of a MET call into the "MET Busy - Call in Progress" state or the MET Operational and Idle" state. Other state transitions are not reported to the Off-line NCCTE GC . Each Virtual

Network update includes all call record, MET Status Table, Circuit Pool Status Table, FES Communication and Terrestrial Interface Pool data sets for the call being updated. The Off-line counterpart GC utilizes update reports to modify its associated tables and call records to reflect concurrency with the On-line GC .

Upon NOC command to assume the On- line NCC role, the GC commences Virtual network management using the call and resource states at the time of switchover

The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. DICTIONARY ITEMS AND DEFINITIONS

Actual GSI

Definition: Current GSI based on TDM changes during MET operation. This field is populated by the NOC based on actions on the CGS. The CMIS cannot create or update this field.

Call Barring Inbound/Outbound Flag

Definition: Describes the call barring entry as

applying to incoming or outgoing calls. If the Call Barring List is flagged as

Inbound, it applies to calls the MET is receiving. If the Call Barring List is flagged as Outbound, it applies to calls the MET is making.

Call Barring Include/Exclude Flag

Definition. Describes the call barring entry as an

included (legal) call or an excluded

(illegal) call. When a Call Barring List is flagged as Include, the MET may only make calls to the numbers or NPAs on the list. Any other call would be denied.

Conversely, if a Call Barring List is flagged as Exclude, the MET may make calls to any number or NPA except those on the list.

Call Barring List Value

Definition: Numbering plan area or phone number in the call barring list. The values that appear in the list are the phone numbers or NPAs that the MET's restriction apply to. The types of restrictions are dictated by the flags for Include/Exclude and

Inbound/Outbound Call Barring. Call Trap Flag

Definition: Indicates call trapping has been initiated for the MET. The GC will trap MET states as they change during MET CGS activity. This information will be provided to the

CMIS on a call record.

Call Type

Definition: Service available on the MET. There are four service types: voice data (2400 or 4800 baud), fax, and alternate voice data

(avd) . For each service the mobile is registered, a service record is created with a single call type indicated. This call type in turn has a unique mobile identification number (min) associated with it.

Carrier

Definition: Name of preferred IXC carrier. This field is a switch field used to support equal access to long distance carriers.

Cellular ESN

Definition: 32 bit ESN that is used by the switch. For dual mode cellular/satellite phones it is the ESN for the cellular portion of the phone and would match the ESN used by the home cellular carrier to identify that mobile terminal.

CGS Time Stamp

Definition: Time stamp was created/modified. Part of the notification of success or failure of

CGS action. Not created or updated by CMIS.

Channel Spacing

Definition: Multiple of frequency step size. This

element is a characteristic of the MET

Class. CMIS will only have the MET Class ID that a particular METs equipment maps to. NE originates this and other data that describes the MET Class and sends it to the NOC.

Check String

Definition: Constant used by the GC to validate the

encryption/decryption algorithm. This element is related to the ASK.

Commanded GSI

Definition: Set by CMIS this is the original GSI stored as a NVRAM (non-volatile RAM) parameter by the MET. Required for each new MET

registered for service. This element is used by the MET to tune to a GC-S channel during commissioning on the CGS. Without the GSI the MET is incapable of logging on to the CGS.

Configuration File

Definition: A file containing the contents of a working configuration that has been saved to disk under a unique name.

Current Configuration

Definition: The set of resources that exist in the

configuration most recently sent to or received from the N C. This is assumed to be the actual configuration of the traffic bearing network at any given time.

Commit a Resource

Definition: Explicit engineer action to add a fully

provisioned interim resource to the working configuration .

Control Group ID

Definition: The CGS is divided into Control Groups that contain circuit pools, signaling channels, bulletin boards, METs, and VNs . A MET may only belong to one Control Group. The control Group assignment is based on the virtual network membership. All VNs a MET is a member of must be in the same control group.

Cust Group

Definition: Identifier for a specialized routing

information used at the switch (e.g., 1024 available cust groups per MSR) . Dialing plans will be implemented for groups of customers through a Customer Group (Cust Group).

Data Hub Id

Definition: Used to route messages during PSTN to IVDM call setup to the proper data hub. This is only applicable for METs that are

participating in the Mobile Packet Data Service.

Date Last Tested

Definition: Time stamp of most recent commissioning

test. This field is populated by the NOC and cannot be created or updated by CMIS.

Default VN

Definition: VN selected if user does not specify VN

during dialing. For METs that belong to only one VN, this can be populated with the VN ID the MET is assigned to by default.

EIRP

Definition: Equivalent Isotropic Radiated Power - power level required for a MET to receive a satellite signal. This element is a characteristic of the MET Class. CMIS will only have the MET Class ID that a

particular METs equipment maps to. NE/SE originates this and other data that describes the MET Class and sends it to the NOC.

Event Argument Id

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

Event Argument Type

Definition: Part of the event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

Event Argument Value

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

Event Argument VMS Type

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

Event Code

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

Event Severity

Definition: Network impact assessment of the trouble event.

Event Time

Definition: Time the event occurred within the network.

Event Type

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events-they arrive unsolicited from the NOC.

External Date Time Stamp

Definition: CMIS generated time stamp used for CMIS

audit purposes in exchanging messages with the CGS.

External Transaction Id

Definition: CMIS generated transaction id used for CMIS audit purposes in exchanging messages with the CGS.

Feature Set

Definition: Identifies MET features within a specific

VN . Fixed features are set up during order processing and require no action by the MET user to invoke a feature. MET activated features must also be set up during order processing but will only be available through some action on the part of the MET use during call process.

FIXED FEATURES include:

* Calling Line Id Presentation (CLIP) - display the calling party's number to a MET.

* Calling Line Id Restriction (CLIR) - prohibition from displaying the METs number when it is calling another party.

* Connected Line Id Presentation (COLP) - display the number the calling MET is connected to.

* Connected Line Id Restriction (COLR) - prohibit display of the connected MET's number to the calling party.

* Sub-addressing (SA) - allows one or more attachments to the MET to be addressed. This is being accomplished through unique phone numbers for service types requiring different equipment. * Call Waiting (CW) - notification to a MET engaged in the call that another call is waiting. MET may accept the other call or ignore it.

* Call Barring (CB) - restricts the MET user's from making or receiving one or more types of calls .

* Operator intervention (01) - allows an operator to break into a call in progress for the MET.

* Operator Assistance (OA) - allows the MET to access an MSAT operator to receive assistance

* Call Priority (CP) - used in conjunction with the system's call queuing function (trunk access priority) presence of this feature gives a MET access to channels at times of congestion ahead of MET's with lower priority. Priority applies only to MET initiated calls.

MET ACTIVATED (dynamic) FEATURES include:

* Call Transfer (CT) - allows sa MET user to transfer an established call to a third party.

* Call Forwarding Unconditional (CFU) - permits a MET to have all calls forwarded to another MET or PSTN number.

* Call Forwarding Busy (CFB) - permits a MET to have all incoming calls attempted when the MET is busy to another MET or PSTN number.

* Call Forward Congestion (CFC) - permits the MET to have all incoming calls attempted when the signaling channels are congested answered with a recorded announcement intercept.

* Call Forward No Reply (CFN) - permits a MET to have all incoming calls attempted when the MET is not answering to another MET or PSTN number. This applies if the MET is blocked, turned off or not answering. * Call Holding (CH) - allows a MET to

interrupt call communication on an existing

connection and then re-establish communications.

* Alternate Voice Data Operation (AVD) - allows a MET user to toggle between voice and data mode during a call. Requires that the call be initiated in voice mode. Only the MET user may toggle between voice and data. This requires a special service type in addition to the activation at set-up of the feature.

* Conference calling (CC) - allows a MET to communicate with multiple-parties including METs and PSTN concurrently.

* Three Party Service (3PS) - allows a MET to who is active on a call to hold that call, make an additional call to a third party, switch from one call to the other (privacy being provided between the calls) and/or release one call and return to the other.

* Malicious Call Trace (MCT) - enables an MSAT operator to retrieve the complete call record at a MET's request for any terminated call in real-time. The operator can then identify the calling party to the MET and take appropriate action.

* Voice Mail (VM) - allows call forwarding to a voice mail box and retrieved of messages by the MET.

* Alternate Accounts Charging (ACC) - allows the MET user to enter in an account code to charge the call to after entering the dialed digits

Fully Provision

Definition: Supply values to all attributes of a

resource Frequency Step Size

Definition: Minimum tuning increment acquired for a MET to tune in an assigned channel. CMIS will only have the MET Class ID that a

particular MET's equipment maps to. NE originates this and other data that

describes the MET Class and sends it to the NOC.

From MET Call Barring Flags

Definition: Describe actions available to a user

originating a call from a MET. These call Barring flags relate to specific types of calls at an aggregate level to indicate if the MET can make or receive a call of a particular type. When this list indicates that an Inclusion or Exclusion to

particular numbers or area codes is

allowed, the values for those restrictions are indicated on a Call Barring List.

FTIN

Definition: Forward Terminal Identification Number - Downloaded to MET from NOC during

commissioning. Used for MET to GC

signaling.

Internal Data Time Stamp

Definition: NOC generated time stamp used for NOC audit purposes.

Internal Transaction Id

Definition: NOC generated transaction is used for NOC audit purposes.

Interim resource

Definition: The resource currently being modified by the engineer. Changes made to an interim resource are not added to the working configuration until the resource is

committed to the working configuration L Band Beam

Definition: Current beam MET is logged into.

Determined by the GC during commissioning.

CMIS has no role in creating or updating this field.

LCC

Definition: Line Class Code - type of phone, required by the switch.

MCC Class Id

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events - they arrive unsolicited from the NOC.

MCC Instance

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events - they arrive unsolicited from the NOC.

MCC Instance Id

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events - they arrive unsolicited from the NOC.

MCC Instance Type

Definition: Part of the Event Record received from the

NOC. CMIS has no part in creating or updating events - they arrive unsolicited from the NOC.

Message Status 1

Definition: Used in the message initiated by the NOC to acknowledge success or failure of a

previously transmitted CMIS request. Used by the DM.

Message Status 2

Definition: Used in the message initiated by the NOC to acknowledge success or failure of a previously transmitted CMIS request. Will be used by the DM.

Message Verb

Definition: Action required at the NOC on data passed in a message from CMIS. This field is in the message relaying the results of a CMIS request.

Modulation Scheme

Definition: Non-standard modulation schemes. CMIS will only have the MET Class ID that a

particular MET's equipment maps to. NE/SE originates this and other data that

describes the MET Class and sends it to the NOC.

MSA

Definition: Mobile Servicing Area - identifies the last call's servicing area. Atomic data element within MSR. Transient data maintained in call processing not on the cellular switch table. Same as MSR.

MSR

Definition: Mobile Servicing Region id (table) contains multiple MSA assignments for the MET. For a roamer, the operator will input the MSR for temporary assignment. Allows up to

1024 cust groups - At CGS startup there will be 1 MSR.

MET ASK

Definition: Access Key MET must match during call

setup/validation.

MET Class ID

Definition: Identifies the operating characteristics of the MET. Associated to MET by CMIS during registration from data supplied by NE/SE. The technical characteristics the MET Class

ID encompasses are not needed by CMIS. These are stored on a table in the NOC and referenced by having the ID on the MET Information record. This ID applies to MET level regardless of how many services, etc. the MET has tied to it.

MET Commanded State

Definition: Current CGS status of MET.

MET Fraud Flag

Definition: Indicates fraud has been detected on the

MET. Updated by GC and CMIS only. This field is set at the MET level regardless of the number of services, etc. the MET has.

MET ID

Definition: CMIS assigned unique MET identifier. This can be a unique random number assigned to each MET registered for service. This is a MET level characteristic set once for the MET regardless of how many services, etc. the MET has. The MET ID is used by the NOC to identify METs It does not have to be used within CMIS as a key field. MET ID cannot be updated once it has been

assigned. A MET that requires a new MET ID for any reason would have to go through the registration process anew.

MET Signaling Code

Definition: Dialed digits from MET that identifies VN selection. Signaling codes would be assigned when a MET has multiple Virtual Network memberships. After the MET user enters the destination phone number, the pound key is hit and then the signaling code is entered if the caller wants to associated the outbound call with a

particular virtual network. When no signaling code is entered, implies default VN be associated with the call.

Pending NVRAM Init Flag

Definition: Instructs the GC to download/initialize

parameters for a MET.

Pending PVT Flag

Definition: This flag indicates that a PVT is required following next MET access. If CMIS

requests a PVT to help diagnose customer troubles, an update would be sent to NOC with the Flag set to Perform PVT after Next MET access (1).

Picsel

Definition: Flag indicating if user has asked for a

preferred IXC carrier. Carrier name is contained in CARRIER field.

Record Type

Definition: Type of record defined by object. Part of the Update Results Record.

Remote

Definition: Remote user - not required by the switch for MSAT Application.

Recent Configuration Event

Definition: This is a serial list of events received from the NOC that pertain to configuration database changes.

Referential Integrity

Definition: Database "key field" relationships that

bind record within the databases, and create dependencies for additions and deletions of table instances.

RF Pin

Definition: Remote feature personal identification

number. A user is prompted for a pin when attempting to use a remote feature. Roam

Definition: Roam Capable - not required by the switch for MSAT Application.

RTIN

Definition: Reverse Terminal Identification Number

which is also the satellite electronic serial number on satellite only and dual mode cellular/satellite METs. This is a unique identifier assigned by manufacturer for each piece of equipment. Within CGS processing the RTIN is used by the GC to signal the MET.

Satellite Id

Definition: Satellite Id of current L-band beam. The

NOC populates this field based on MET commissioning. CMIS does not ever create or update this field.

SCM

Definition: Station Class Mark.

Secure Disable Flat

Definition: Channel Unit security check flag. Setting this flag to bypass security would disable ASK verification during call processing for a MET. CMIS cannot change this flag.

Signaling Priority

Definition: Number of MET signaling requests to the GC during network congestion. Assigned at the MET level - each MET may have only one signaling priority regardless of the number of VN memberships it has. The highest priority level is 0 and the lowest is seven.

TDM Change Enable Flat

Definition: Restriction on MET from changing TDM (TDM is the GSI) Telephone Number

Definition: Phone number associated with a call type

(voice, data, fax, avd) in a given virtual network.

Template

Definition: An initial set of default attribute values for each resource being added.

To MET Call Barring Flags

Definition: Describes actions available to a user

receiving a call at their MET.

Trunk Access Priority

Definition: Satellite trunk queuing priority used

during network congestion. Determines access to channels.

Virtual Network Id

Definition. Identifies the Virtual Network that the

service and feature profiles relate to. Within a single VN a MET may have one voice, data, fax and/or avd service type. Features and restrictions for those

services are defined on the basis of the METs membership in that VN If the MET required an additional instance of a service that it already subscribed to, (e.g. a second voice number) , a second virtual network assignment would be

required. Features and restrictions for that second membership can be defined with no relation to the existing VN membership, but all elements that relate to the MET level cannot change without a ripple effect to the other services.

VMS Instance Type

Definition: Part of the Event Message Vocoder Id

Definition: Vocoder version currently installed in the

MET. CMIS will only have the MET Class ID that a particular METs equipment maps to. NE/SE originates this and other data that describes the MET Class and sends it to the NOC.

Working Configuration

Definition: The set of resources currently being

modified by the engineer. This may be an existing, complete configuration which the engineer is modifying, or may be a new, partial (or initially empty)

configuration.

Claims

What is claimed is:

1. In a mobile satellite system including a satellite communication switching office having a satellite antenna for receiving/transmitting a

satellite message via a satellite from/to a vehicle using a mobile communication system, a central

controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the vehicle via the satellite, a method of providing satellite communication and satellite

management for multiple users in a virtual network arrangement, said method comprising the steps of:

(a) first and second mobile earth terminals (METs) registering with the mobile satellite system;

(b) the first MET selecting a virtual network identifier (VN ID) representing a virtual network group including at least the first and second METs to

establish voice communication therewith;

(c) the first MET transmitting the VN ID to the central controller;

(d) the central controller receiving the VN ID, allocating a frequency for the virtual network group, and broadcasting the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith;

(e) the second MET tuning to the frequency in response to the message broadcast by the central controller; and

(f) the first and second METs communicating with each other on the frequency.

2. The method according to claim 1, further comprising the steps of: (1) a third MET included in the virtual network group registering with the mobile satellite system;

(2) the central controller broadcasting the message to the virtual network group including the third MET informing the virtual network group of the allocated frequency and the voice communication

associated therewith; and

(3) the third MET tuning to the allocated

frequency for the virtual network group to gain access thereto and communicate with the first and second METs.

3. The method according to claim 1, wherein the central controller controls the satellite communication of the virtual network arrangement including virtual network parameters used by the first and second METs.

4. The method according to claim 1, wherein the central controller collects billing information

regarding the satellite communication and transmits the billing information to the mobile satellite system, and wherein the mobile satellite system charges a service fee to a customer that has requested the virtual network arrangement .

5. The method according to claim 1, further comprising the steps of :

(1) a non-MET accessing the mobile satellite system via one of a public switched telephone network and a cellular network to initiate a communication with the virtual network group including at least one of the first and second METs;

(2) the central controller broadcasting the message to the virtual network group informing the virtual network group of the allocated frequency and the voice communication associated therewith; and (3) the at least one of the first and second METs tuning to the frequency in response to the message broadcast by the central controller to communicate with the non-MET in the virtual network arrangement.

6. The method according to claim 1, further comprising the steps of:

(1) the first MET selecting the virtual network identifier (VN ID) representing the virtual network group including the first MET and a non-MET serviced by one of a public switched telephone network and a cellular network to establish voice communication therewith;

(2) the first MET transmitting the VN ID to the central controller;

(3) the central controller receiving the VN ID, determining that the virtual network group includes the non-MET, and broadcasting a non-MET message to the one of the public switched telephone network and the cellular network including the voice communication associated therewith; and

(4) the one of the public switched telephone network and the cellular network receiving the non-MET message from the central controller and transmitting the non-MET message to the non-MET to establish the virtual network arrangement between the MET and the non-MET.

7. In a mobile satellite system including a satellite communication switching office having a satellite antenna for receiving/transmitting a

satellite message via a satellite from/to a vehicle using a mobile communication system, a central

controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the vehicle via the satellite, a system for providing satellite communication between multiple users in a virtual network arrangement, comprising: first and second mobile earth terminals (METs) responsively connected to and registering with the mobile satellite system, the first MET selecting a virtual network identifier (VN ID) representing a virtual network group including the first and second METs to establish voice communication therewith and transmitting the VN ID; and

a central controller responsively connected to the first and second METs, the central controller receiving the VN ID from the first MET, validating the first MET for communication, validating the VΝ ID, allocating a frequency for the virtual network group, and

broadcasting the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice

communication associated therewith, the second MET tuning to the frequency in response to the message broadcast by the central controller, and the central controller assigning the first MET as current speaker for the virtual network group.

8. The system according to claim 7, wherein the central controller controls the satellite communication including virtual network parameters used by the first and second METs .

9. The system according to claim 7, wherein the central controller collects billing information

regarding the satellite communication and transmits the billing information to the mobile satellite system, and wherein the mobile satellite system charges a service fee to a customer that has requested the virtual network arrangement.

10. The system according to claim 7, wherein a non-MET accesses the mobile satellite system via one of a public switched telephone network and a cellular network to initiate a communication with the virtual network group including at least one of the first and second METs,

the central controller broadcasts the message to the virtual network group informing the virtual network group of the allocated frequency and the voice

communication associated therewith, and

the at least one of the first and second METs tunes to the frequency in response to the message broadcast by the central controller to communicate with the non-MET in the virtual network arrangement.

11. The system according to claim 7, wherein the first MET selects the virtual network

identifier (VN ID) representing the virtual network group including the first MET and a non-MET serviced by one of a public switched telephone network and a cellular network to establish voice communication therewith, and transmits the VΝ ID to the central controller,

the central controller receives the VN ID,

determines that the virtual network group includes the non-MET, and broadcasts a non-MET message to the one of the public switched telephone network and the cellular network including the voice communication associated therewith, and

the one of the public switched telephone network and the cellular network receives the non-MET message from the central controller and transmits the non-MET message to the non-MET to establish the virtual network arrangement between the MET and the non-MET.

12. The system according to claim 7, further comprising a third MET responsively connected to said central controller and included in the virtual network group registering with the mobile satellite system, and wherein

the central controller broadcasts the message to the virtual network group including the third MET informing the virtual network group of the allocated frequency and the voice communication associated therewith,

the third MET generating a scrambling vector for access to the voice communication, and tuning to the allocated frequency for the virtual network group using the scrambling vector to gain access thereto.

13. A satellite network system comprising:

a satellite antenna for receiving and transmitting messages via a satellite and satellite beams to and from feederlink earth stations (FESs) connected to at least one land line communications network and mobile earth terminals (METs) of a mobile communication system;

a satellite communication switching office

connected to said antenna and coupled through a

satellite interface system to a central controller; and a network operations center (NOC) for managing and controlling resources of the satellite network system, the NOC communicating with various internal and

external entities via a control network, said NOC comprising:

data management means for transmission and receipt of information with other components of the network operations center, said data management means including a NOC data base;

configuration management means for allocating system resources; network management means for updating network functions;

call records management means for enabling

monitoring of customer usage;

event management means for detecting fault

conditions; and

operator interface means for transmitting system information to an operator station.

14. In a mobile satellite system including a satellite communication switching office and network system having a satellite antenna for receiving and transmitting a satellite message via a satellite and satellite beams to and from feederlink earth stations

(FESs) and mobile earth terminals (METs) using a mobile communication system, a satellite interface system, a central controller receiving and transmitting the satellite message to and from the satellite

communication switching office, the mobile satellite system being responsively connected to said mobile communication system and comprising:

a network operations center (NOC) managing and controlling the resources of the satellite network system and carrying out the administrative functions associated with the management of the network system, the NOC communicating with various internal and

external entities via a control network;

a first network communications controller (NCC) managing the real time allocation of circuits between METs and FESs for the purposes of supporting

communications, available circuits being held in circuit pools managed by group controllers (GCs) within the NCC, the NCC communicating with the NOC via a satellite network internetwork, with FESs via Ku-to-Ku band interstation signaling channels or terrestrial links, and with METs via Ku-to-L band signaling

channels;

a FES supporting communications links between METs, the public switched telephone network (PSTN), private networks, and other METs, call completion and service feature management being accomplished via in-band signaling over the communication channel following the establishment of such a channel, the FES including a gateway FES providing mobile telephone service (MTS) and mobile telephone cellular roaming service (MTCRS) services, and a base FES providing mobile radio service (MRS) and net radio (NR) services; and

a group controller subsystem (GCS) incorporating one or multiple group controllers (GC), each GC

maintaining state machines for every call in progress within its control group and allocating and de-allocating circuits for FES-MET calls within each beam of the system, managing virtual network call

processing, MET authentication, and providing elements of call accounting, the GC providing satellite

bandwidth resources to the NOC for AMS(R)S resource provisioning and monitoring the performance of call processing and satellite circuit pool utilization, and performing MET management, commissioning and periodic performance verification testing and database

management.

15. In a mobile satellite system including a satellite communication switching office (SCSO) having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to a mobile communication system (MCS), a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the MCS via the satellite to another party, a method of performing a call setup procedure in the mobile satellite system from a call initiated by a destination served by a public switched telephone network (PSTN) to the MCS, said method comprising the steps of:

(a) receiving by the SCSO a call from the

destination served by the PSTN;

(b) transmitting by the SCSO to the central controller a channel request including a destination number;

(c) determining by the central controller an identity of the MCS responsive to the destination number, and transmitting a call announcement;

(d) acknowledging by the MCS the call announcement to the central controller;

(e) transmitting frequency assignments to the MCS and to the SCSO, the frequency assignment including the call type, and the destination phone number, and a security field used to verify the MCS's identity;

(f) receiving by the MCS the frequency assignment, and transmitting an identification message to the SCSO;

(g) verifying by the SCSO the identity of the MET responsive to the identification message;

(h) upon successful verification in said verifying step (g), transmitting by the SCSO a ring command to the MCS;

(l) receiving by the MCS of the ring command, generating a ringing signal to a MET user, and

transmitting a ring command acknowledgement to the SCSO; (i) receiving by the SCSO the ring command acknowledgement from the MCS;

(k) once the call setup is complete and the MET user has acknowledged the ringing signal by going off-hook, transmitting by the MCS a disable signal to the SCSO and disabling voice activation in the MCS for a predetermined period of time; (1) upon detection of the MCS switching to a voice mode, switching by the SCSO to the voice mode, and re-enabling voice activation by the MCS; and

(m) establishing voice communication between the PSTN and the MCS.

16. In a mobile satellite system including a satellite communication switching office (SCSO) having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to a mobile communication system (MCS) , a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the MCS via the satellite to another party, a method of performing a call setup procedure in the mobile satellite system from a call initiated by the MCS to a destination served by a public switched telephone network (PSTN), said method comprising the steps of:

(a) initiating the call by the MCS;

(b) the MCS formatting and transmitting an access request message including call type and destination number;

(c) receiving by the central controller the access request message, and transmitting frequency assignments to the MCS and to the SCSO, the frequency assignment including the call type, and the destination phone number, and a security field used to verify the MCS's identity;

(d) receiving by the MCS the frequency assignment, and transmitting an identification message to the SCSO;

(e) verifying by the SCSO the identity of the MET responsive to the identification message; (f) upon successful verification in said verifying step (e), switching by the SCSO and the MCS from call setup mode to voice mode;

(g) transmitting by the SCSO a disable signal to the MCS to disable voice activation in the MCS for a predetermined time period after which voice activation is re-enabled in the MCS, and transmitting a

destination number to the PSTN; and

(h) establishing voice communication between the PSTN and the MCS.

AMENDED CLAIMS

[received by the International Bureau on 9 May 1997 (09.05.97);

new claims 17-20 added; remaining claims unchanged (5 pages)]

17. In a mobile communication system including a

communication switching office for receiving/transmitting a message, a central controller receiving/transmitting the message from/to the communication switching office, a method of providing communication and management for multiple users in a virtual network arrangement, said method comprising the steps of:

(a) first and second mobile earth terminals (METs)

registering with the mobile communication system,

(b) the first MET selecting a virtual network identifier (VN ID) representing a virtual network group including at least the first and second METs to establish voice communication therewith;

(c) the first MET transmitting the VN ID to the central controller,

(d) the central controller receiving the VN ID, allocating a frequency for the virtual network group, and broadcasting tne message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith;

(e) the second MET tuning to the frequency in response to the message broadcast by the central controller, and

(f) the first and second METs communicating with each other on the frequency.

18. A network system comprising:

an antenna for receiving and transmitting messages to and from mobile earth terminals (METs) of a mobile communication system;

a communication switching office connected to said antenna and coupled through an interface system to a central controller, and

a network operations center (NOC) for managing and

controlling resources of the network system, the NOC

communicating with various entities via a control network, said NOC comprising:

data management means for transmission and receipt of information with other components of the network operations center, said data management means including a NOC data base; configuration management means for allocating system

resources;

network management means for updating network functions; call records management means for enabling monitoring of customer usage;

event management means for detecting fault conditions; and operator interface means for transmitting system information to an operator station.

19. In a mobile communication system including a

communication switching office for receiving/transmitting a message, a central controller receiving/transmitting the message from/to the communication switching office, the mobile

communication system comprising:

a network operations center (NOC) managing and controlling the resources of the mobile communication system and carrying out the administrative functions associated with the management of same, the NOC communicating with various internal and external entities via a control network;

a first network communications controller (NCC) managing the real time allocation of circuits for the purposes of supporting communications, available circuits being held in circuit pools managed by group controllers (GCs) within the NCC;

a FES supporting communications links between at least one of mobile earth terminals (METsj, the public switched telephone network (PSTN), private networks, and other METs, and providing call completion and service feature management, the FES including a gateway FES providing access to at least one of mobile

telephone service (MTS) and mobile telephone cellular roaming service (MTCRS) services, and a base FES providing mobile radio service (MRS) and net radio (NR) services; and

a group controller subsystem (GCS) incorporating one or multiple group controllers ( GC ), each GC at least one of

maintaining controlling calls in progress within its control group and allocating and de-allocating circuits, managing virtual network call processing, MET authentication, and providing elements of call accounting, monitoring the performance of call processing and circuit pool utilization, performing MET

management, commissioning, periodic performance verification testing and database management.

20 A method of performing a call setup procedure in a mobile satellite system from a call initiated by a mobile

communication system (MCS) to a destination served by a public switched telephone network (PSTN), said method comprising the steps of :

(a) initiating a call by the MCS,

(D) receiving by the central controller the call, and transmitting frequency assignments to the MCS and to a satellite communication switching office (SCSO),

(c) receiving by the MCS the frequency assignment, and transmitting an identification message to the SCSO,

(d) verifying by the SCSO the identity of the MET

responsive to the identification message,

(e) upon successful verification in said verifying step (d), switching by the SCSO and the MCS from call setup mode to voice mode;

(f) transmitting by the SCSO a disable signal to the MCS to disable voice activation in the MCS for a predetermined time period after which voice activation is re-enabled in the MCS, and transmitting a destination number to the PSTN; and

(g) establishing voice communication between the PSTN and the MCS.