RU2364026C2 - Method and system of data transfer in communication system - Google Patents

Abstract

FIELD: communication facilities.

SUBSTANCE: invention concerns data transfer in wired or wireless communication systems. To achieve the effect, each of first multiple access terminals includes: receiver; memory environment configured to store instructions; and at least one processor communicated to receiver and memory environment and capable of instruction pack processing for: processing of signals presented by the receiver for interval distribution, where each interval is related to multiple access mode; processing of signals presented by the receiver for making of scheduling solution regarding interval related to first multiple access mode, where interval is divided into first and second parts, and firs part includes maintenance channels; selection of data multiplexing mode where first mode includes introduction of user data only to the first part of interval related to the first multiple access mode, using multiplex format; second mode includes introduction of user data only in at least one subdivision of the second part of interval related to the first multiple access mode where each of at least one subdivision is related to multiplex format; and third mode includes introduction of user data to the interval related to the first multiple access mode, by combination of first and second modes; and command delivery to transmitter for transmission of user data within the interval related to the first multiple access mode, using selected data multiplexing mode according to the scheduling solution.

EFFECT: enhanced data bandwidth in feedback channel.

34 cl, 17 dwg, 5 tbl

Description

FIELD OF THE INVENTION

The present invention relates to the transmission of information in wired or wireless communication systems. In particular, the present invention relates to a method and system for transmitting data in such a communication system.

State of the art

Communication systems have been developed to enable the transmission of information signals from a departure station to a physically distinct destination station. When transmitting an information signal from a departure station through a communication channel, the information signal is first converted to a form suitable for efficient transmission over the communication channel. The conversion or modulation of the information signal involves changing the parameter of the carrier wave in accordance with the information signal so that the spectrum of the resulting modulated carrier wave is limited within the bandwidth of the communication channel. At the destination station, the initial information signal is reconstructed from the modulated carrier wave received over the communication channel. In the general case, such restoration is performed using a process inverse to the modulation process applied at the departure station.

Modulation also facilitates multiple access, that is, the simultaneous transmission and / or reception of several signals over a common communication channel. Several multiple access techniques are known in the art, such as time division multiple access (TDMA) or frequency division multiple access (FDMA). Another type of multiple access technique is a Code Division Multiple Access (CDMA) system, compliant with the TIA / EIA / IS-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wide-Band Spread Spectrum Cellular System ”, Which is hereinafter referred to as the IS-95 standard. The use of CDMA techniques in a multi-access communication system is disclosed in US Patent Application No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE-ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS” and in US Patent Application No. 5,103,459, entitled “SYSTEM AND METHOD FOR CDMA CELLULAR TELEPHONE SYSTEM ”owned by the present applicant.

Multiple access communication systems may be wired or wireless and may transmit voice traffic and / or data stream. An example of a communication system transmitting both voice traffic and data flow is a system that complies with the IS-95 standard, which defines the transmission of voice traffic and data flow over a communication channel. A method for transmitting data in encoded frames of a fixed-length channel is described in detail in US Patent Application No. 5,504,773, entitled “METHOD AND APPARATUS FOR THE FORMATTING OF DATA FOR TRANSMISSION”, owned by the present applicant. In accordance with the IS-95 standard, data stream or voice traffic is divided into encoded channel frames of 20 milliseconds in length with a data rate of up to 14.4 Kbps. An additional example of a communication system transmitting both voice traffic and data flow is a communication system corresponding to the “3rg Generation Partnership Project” (3GPP), implemented in a set of documents, including documents with numbers 3G TS 25.211, 3G TS 25.212, 3G TS 25.213 and 3G TS 25.214 (W-CDMA standard), or “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems” (IS-2000 standard).

The term base station means a network access entity with which subscriber stations communicate. With reference to the IS-856 standard, the base station is also called an access point. The term cell refers to the geographic coverage area or coverage area of a base station served by a base station, depending on the context in which the term is used. The term sector refers to a segment of a base station serving as a segment of a geographical area served by a base station.

The term “subscriber station” is used herein to mean the entity with which the access network is associated. With reference to the IS-856 standard, a base station is also called an access terminal. The subscriber station may be mobile or stationary. A subscriber station can be any data device that communicates wirelessly or wired, such as fiber optic or coaxial cables. In addition, the subscriber station can be any of many types of devices, including, but not limited to, a PC Card, a flash card, an external or internal modem, or a cordless or wired telephone. The subscriber station, which is in the process of establishing an active connection with the transmission channel with the base station, is said to be in a state of establishing communication. A subscriber station that has established an active connection to a transmission channel is called an active subscriber station, and its status is called a transmission state.

The term access network refers to a plurality of at least one base station (BS) and one or more base station controllers. The access network transmits information signals between multiple subscriber stations. The access network can be additionally connected to additional networks outside the access network, such as a corporate local network or the Internet, and can transmit information signals between each base station and such external networks.

In the multiple access wireless communication system described above, connections between users are made through one or more base stations. The term user means both animate and inanimate entities. The first user on one wireless subscriber station communicates with the second user on the second wireless subscriber station by transmitting an information signal on the reverse link to the base station. The base station receives the information signal and transmits the information signal via a direct communication channel to the second subscriber station. If the second subscriber station is outside the area served by the base station, then the base station sends data to another base station in whose service area the second subscriber station is located. Then, the second base station transmits an information signal over the forward communication channel of the second subscriber station. The term forward link refers to transmissions from a base station to a subscriber's wireless station, and the term reverse link refers to transmissions from a subscriber's wireless station to a base station. Similarly, a communication session can be made between the first user of the subscriber's wireless station and the second user of the landline station. The base station receives data from the first user of the subscriber’s wireless station on the reverse link and sends the data through the public switched telephone network (PSTN) to the second user of the landline station. In many communication systems, for example, IS-95, W-CDMA and IS-2000, different frequencies are allocated to the forward and reverse links.

The study of only voice traffic transmission services and data flow only transmission services revealed some significant differences between the two types of services. One difference relates to the delay in delivering the amount of information. Voice traffic services impose strict and fixed delay requirements. Typically, the total one-way delay of a predetermined amount of voice traffic information called a voice frame should be less than 100 ms. In contrast, the full one-way delay of the data stream can be a variable parameter used to optimize the efficiency of the data stream services provided by the communication system. For example, multi-user diversity, delay in transferring data to better conditions, more efficient error correction coding techniques that require significantly longer delays than delays that voice traffic services may allow, and other techniques may be used. An exemplary effective coding scheme for data is disclosed in provisional application for US patent No. 08 / 743,688, entitled "SOFT DECISION OUTPUT DECODER FOR DECODING CONVOLUTIONALLY ENCODED CODEWORDS", dated November 6, 1996, is currently transferred to patent application US No. 5,933,462 of August 3 1999, registered in the name of Sindhushayana et al. and owned by the present applicant.

Another significant difference between voice traffic services and data stream services is that the former require a fixed and general service category (GOS) for all users. As a rule, for digital communication systems providing voice traffic services, this requirement is transformed into a requirement of a fixed and equal transmission speed for all users and a requirement of the maximum allowable value for error rates in voice frames. On the other hand, the category of service (GOS) for data services may differ from user to user and may be a variable parameter, whose optimization increases the overall efficiency of the data stream service provided by the communication system. A service category (GOS) for a data stream service provided by a communication system is generally defined as a total delay occurring in transmitting a predetermined amount of data stream information, such as a data packet. The term packet means a group of bits, including data (payload) and controls, arranged in a specific format. Control elements include, for example, a title, a quality metric, and other elements known to a person skilled in the art. The quality metric includes, for example, cyclic redundancy check, parity, and other elements known to one skilled in the art.

Another significant difference between voice traffic services and data stream services is that the former require a reliable communication channel. When a subscriber station exchanging voice traffic with the first base station moves to the cell boundary served by the first base station, the subscriber station enters the overlap zone with another cell served by the second base station. A subscriber station in such a zone establishes a voice traffic transmission session with a second base station, while maintaining a voice traffic transmission session with a first base station. During this simultaneous transmission, the subscriber station receives a signal that carries the same information from both base stations. Similarly, both base stations also receive signals carrying information from the subscriber station.

Such simultaneous communication sessions are called soft call transfer from one base station to another during the movement of the user. When, over time, the subscriber station leaves the cell served by the first base station and terminates the voice traffic session with the first base station, the subscriber station continues the voice traffic session with the second base station. Due to the fact that the soft transfer of a call from one base station to another during the user's movement is a do-it-yourself mechanism, the soft transfer of a call from one base station to another during the user's movement minimizes the likelihood of a call break. A method and system for communicating with a subscriber station through more than one base station during a soft call transfer from one base station to another during a user’s movement is disclosed in US Pat. No. 5,267,261, entitled “MOBILE ASSISTED SOFT HAND-OFF IN A CDMA CELLULAR TELEPHONE SYSTEM ”issued to the present applicant.

A softer call transfer from one base station to another during the user's movement is a similar process in which a communication session occurs through at least two sectors of a multi-sector base station. The process of softer transfer of a call from one base station to another during the user’s movement is described in detail in US Patent Application No. 08 / 763,498, pending “METHOD AND APPARATUS FOR PERFORMING HAND-OFF BETWEEN SECTORS OF A COMMON BASE STATION” dated December 11, 1996, currently US Patent No. 5,933,787, dated August 3, 1999, issued by Gilhousen et al., owned by the present applicant. Thus, both softer and softer call transfer from one base station to another during the movement of the user lead to excessive transfers from two or more base stations to improve reliability.

This additional reliability is not so important for communication sessions with the transmission of a data stream, since data packets received in error may be retransmitted. Important parameters for data services are the transmission delays required to transmit the data packet and the average throughput of the communication system for transmitting the data stream. Transmission delay does not have the same effect on data transmission as it does on voice transmission, but transmission delay is an important metric for measuring the quality of a communication system for data transmission. Average throughput is a measure of the efficiency of the data transfer ability of a communication system. Due to the weak requirements for transmission delay, the transmission power and resources used to support soft call transfer from one base station to another during the movement of the user on the forward communication channel can be used to transmit additional data, thereby increasing the average throughput at help increase efficiency.

The situation is different in the case of a reverse communication channel. Several base stations may receive a signal transmitted by a subscriber station. Due to the fact that packet retransmission from a subscriber station requires additional power from a limited power source (battery), it can be effective to support soft call transfer from one base station to another while the user is moving on the reverse communication channel, allocating resources to several basic stations for receiving and processing data packets transmitted from the subscriber station. This use of soft call transfer from one base station to another during the user's movement increases both coverage and reverse link capacity, as described by Andrew J. Viterbi and Klein S. Gilhousen: “Soft Handoff Extends CDMA Coverage and Increases Link Capacity ”, IEEE Journal on Selected Area in Communications, Vol. 12, No. 8, October 1994. The term soft call transfer from one base station to another during the movement of a user means a communication session between a subscriber station and two or more sectors, where each sector belongs to a different cell. In the context of the IS-95 standard, reverse link transmission is received by both sectors and forward link transmission is performed simultaneously on two or more sectors direct communication channels. In the context of the IS-856 standard, data transmission over a forward communication channel is not performed simultaneously between one of two or more sectors and an access terminal. In addition, a softer call transfer from one base station to another during the movement of the user can be used for this purpose. The term softer call transfer from one base station to another during a user’s movement means a communication session between a subscriber station and two or more sectors, where each sector belongs to the same cell. In the context of the IS-95 standard, reverse link transmission is received by both sectors, and forward link transmission is performed simultaneously on one of two or more direct sectors communication channels. In the context of the IS-856 standard, data transmission over a forward communication channel is not performed simultaneously between one of two or more sectors and an access terminal.

It is well known that the quality and efficiency of data transmission in wireless communication systems depends on the state of the communication channel between the source terminal and the destination terminal. This condition, estimated using, for example, signal-to-interference and noise (SINR), is influenced by several factors, for example, path loss, and a change in path loss for the subscriber station within the coverage area of the base station, interference from other subscriber stations both from the same cell and from other cells, interference from other base stations and other factors known to a person skilled in the art. In order to maintain a certain level of service under the influence of variable channel states, TDMA and FDMA systems resort to the separation of users at different frequencies and / or time intervals and support multiple use of frequencies to reduce interference. Frequency reuse divides the available spectrum into multiple sets of frequencies. This cell uses frequencies from only one set; cells directly adjacent to this cell may not use the frequency from the same set. In CDMA systems, the same frequency is used in each cell of the communication system, thereby improving overall efficiency. Interference is reduced using other techniques, for example, orthogonal coding, controlled transmit power, variable data rate, and other techniques known to one skilled in the art.

The concepts mentioned above were used to develop a communication system for transmitting only a data stream, known as a high data rate (HDR) communication system. Such a communication system is disclosed in detail in US Patent Application No. 08 / 963,386, pending “METHOD AND APPARATUS FOR HIGH RATE PACKET DATA TRANSMISSION”, November 3, 1997, currently US Patent Application No. 6,574,211 of June 3 2003, registered by Padovani et al. and owned by the present applicant. An HDR communication system is standardized as the industry standard TIA / EIA / IS-856, hereinafter referred to as the IS-856 standard.

The IS-856 standard defines a set of data rates ranging from 38.4 kbps to 2.4 Mbps, at which an access point (AP) can send data to a subscriber station (access terminal). Since the access point is similar to the base station, the terminology related to cells and sector is the same as the terminology in voice systems. In accordance with the IS-856 standard, the data to be transmitted over the forward communication channel is divided into data packets, and each packet is transmitted over one or more intervals (time intervals) into which the direct communication channel is divided. In each time interval, data is transmitted from the access point to one and only one access terminal located within the coverage area of the access point at the maximum data rate that can be supported by a direct communication channel and communication system. The access terminal is selected in accordance with the states of the forward link between the access point and the access terminal. The state of the direct communication channel depends on the interference and path loss between the access point and the access terminal, both of which change over time. Losses on the track and change in losses on the track are used by scheduling the access point’s transmissions at time intervals during which the conditions of the direct communication channel of the access terminal to a specific access point satisfy a certain criterion, which makes it possible to transmit with lower power or higher data rates which are transmitted to the remaining access terminals, thereby increasing the spectral efficiency of transmissions on the forward communication channel.

In contrast, in accordance with the IS-856 standard, data transmissions on the reverse link come from a plurality of access terminals located within the coverage area of the access point. Moreover, because the antenna of the access terminal is omnidirectional, any access terminal within the coverage area of the access point can receive these data transmissions. Accordingly, transmissions on the reverse communication channel are subject to several sources of interference: upper channels with code separation from other access terminals, data transmission from access terminals located in the coverage area of the access point (access terminals in the same cell), and data transmission from access terminals, located in the coverage area of other access points (access terminals from other cells). Multiplexing, in a general sense, means the transmission of multiple data streams over a single communication channel.

When developing wireless data services, the emphasis was on increasing the throughput of the direct communication channel, following the model of Internet services; where the service provides a high data rate in response to requests from the node. The server-to-node direction is similar to a direct communication channel requiring high bandwidth, and the node-server and / or data transfer requests are carried out with less bandwidth. Nevertheless, modern developments show an increase in applications with intensive use of the reverse communication channel, for example, file transfer protocol (FTP), video conferencing, games or other services with a constant data transfer rate. Such applications require improved reverse link efficiency to achieve higher data rates, so applications require higher reverse link throughput. Thus, in the art there is a need to increase the throughput of the reverse link, ideally providing symmetrical throughputs on the forward and reverse links.

Implementations of the inventive method and apparatus for transmitting over a reverse communication channel are disclosed in US patent applications pending 10/313,553 and 10/313,594, entitled “METHOD AND APPARATUS FOR DATA TRANSMISSION OVER A REVERSE LINK IN A COMMUNICATION SYSTEM” of 6 December 2002, issued to the assignee of the present invention. The invented method and apparatus for transmitting over a reverse communication channel may not be fully applicable to already established (traditional) communication systems due to budgetary considerations, as explained in detail below. Accordingly, the introduction of the invented method and device for transmitting over the reverse communication channel according to US patent applications No. 10 / 313.553 and 10 / 313.594 in traditional communication systems is a problem associated with the above budgetary considerations and the joint existence of subscriber stations, capable of receiving the invented reverse communication channel (new subscriber stations) and subscriber stations capable of receiving only the reverse communication channel in accordance with the IS-856 standard (traditional subscriber stations). In addition, the invented method and apparatus for transmitting on a reverse communication channel additionally creates a need for a method and apparatus for controlling power and determining a data transfer rate.

Thus, there is a need for a device and method that makes it possible to increase the throughput of the reverse link, taking into account the above problems.

This application is related to US Patent Application No. 10 / 389,176 (Patent Attorney No. 030215U2), entitled “Method and System for Data Transmission in a Communication System” of March 13, 2003; US Patent Application No. 10 / 389,716 (Patent Attorney No. 030215U3), entitled “Method and System for Estimating Parameters of a Link For Data Transmission in a Communication System” dated March 13, 2003; and US Patent Application No. 10 / 389,656 (Patent Attorney No. 030215U4), entitled “Method and System for Power Control in a Communication System” of March 13, 2003, all belong to the applicant of the present invention.

Disclosure of invention

In one aspect of the present invention, the above needs are solved by obtaining each of the first and second subset of the plurality of access terminals assigning a sequence of slots, each slot is associated with a multiple access mode, where the second subset is mutually excluded from the first subset; each of the first subset of access terminals receiving a scheduling decision for the interval associated with the first multiple access mode, the interval is divided into the first part and the second part, the first part contains overhead channels; each of the first subset of access terminals selecting a mode for multiplexing data, where the first mode includes embedding user data only in the first part of the interval using the multiplexing format; the second mode includes embedding user data only in at least one subsection of the second part of the interval, where each of the at least one subsection is associated with a multiplexing format; and the third mode includes embedding user data in the interval using the first and second mode; and transmitting user data from at least one of the first subset of access terminals in an interval associated with the first multiple access mode using the selected data multiplexing mode in accordance with the scheduling decision.

In another aspect of the present invention, the above needs are addressed by each of the second subset of access terminals selecting a mode for multiplexing data, where the third mode includes embedding user data in only the first part of the interval using the multiplexing format; the fourth mode includes embedding user data only in the second part of the interval using the multiplexing format; and the third mode includes embedding user data in an interval with sharing the first and second mode; and transmitting user data from at least one of the second subset of access terminals in an interval associated with the second multiple access mode using the selected data multiplexing mode.

In another aspect of the present invention, the above needs are met by transmitting user data from at least one of a second subset of access terminals in an interval associated with a first multiple access mode using a first data multiplexing mode.

In another aspect of the present invention, the above needs are solved by transmitting user data from a third subset of a plurality of access terminals; said third subset is mutually excluded from the first subset and the second subset.

Brief Description of the Drawings

Figure 1 is a conceptual block diagram of a communication system capable of functioning in accordance with implementations of the present invention.

Figure 2 - implementation of the waveform of the forward communication channel in the present invention.

3 is an illustration of a method for transmit power control commands and packet providing commands on a reverse power control channel.

4A-4D are an illustration of an implementation of a reverse link waveform.

5A-5C are an illustration of an implementation of a reverse link architecture.

6A-6C is a conceptual block diagram of an OFDM communication system.

7 is an illustration of the implementation of data transmission on the reverse communication channel.

Fig. 8 is an illustration of an implementation of data retransmission on the reverse link.

9 is an illustration of an access terminal.

10 is an illustration of an access point.

The implementation of the invention

Figure 1 illustrates a conceptual diagram of a communication system. Such a communication system can be built in accordance with the standard IS-856. The access point 100 transmits data to the access terminal 104 on the forward communication channel 106 (1) and receives data from the access terminal 104 on the reverse communication channel 108 (1). Similarly, the access point 102 transmits data to the access terminal 104 on the forward communication channel 106 (2) and receives data from the access terminal 104 on the reverse communication channel 108 (2). Data transmission via a direct communication channel occurs from one access point to one access terminal at a maximum or near maximum data transfer rate, which is supported by a direct communication channel and a communication system. Additional channels of the forward communication channel, for example, a control channel, may be transmitted from multiple access points to one access terminal. Data transmission on the reverse communication channel may occur from one access terminal to one or more access points. The access point 100 and the access point 102 are connected to the access network controller 110 via reverse links 112 (1) and 112 (2). The reverse link is the communication channel between the controller and the access point. Although only two access terminals and one access point are shown in FIG. 1, this is only to simplify the explanation, and the communication system may comprise a plurality of access terminals and access points.

After registration, which allows the access terminal to access the access network, the access terminal 104 and one access point, such as an access point 100, establish a communication channel using a predetermined access procedure. In a connected state resulting from a predetermined access procedure, the access terminal 104 is capable of receiving data and control messages from the access point 100 and is capable of transmitting data and control messages to the access point 100. Access terminal 104 continuously searches for other access points that can be added to the active set of access terminal 104. The active set includes a list of access points capable of establishing a communication session with the access terminal 104. When such an access point is found, the access terminal 104 calculates a quality metric for the direct channel of the access point, which may include signal to interference and noise ratio (SINR). SINR can be determined in accordance with the pilot signal. Access terminal 104 searches for other access points and determines the SINR of access points. At the same time, the access terminal 104 calculates a quality metric for the direct communication channel with each access point in the active set of the access terminal 104. If the quality metric of the forward link with a specific access point is above a predetermined add threshold or below a predetermined delete threshold for a predetermined time period, the access terminal 104 transmits this information to the access point 100. Subsequent messages from the access point 100 may be sent to the access terminal 104 in order to add or remove a specific access point from the active set of the access terminal 104.

Access terminal 104 selects a serving access point from the active set of access terminal 104 based on a number of parameters. A serving access point is an access point that is selected for data transmission by a specific access terminal or an access point that transmits data to a specific access terminal. The set of parameters may include, for example, any one or more current or earlier SINR measurements, error bit rate, error packet rate, or any other known parameter. Thus, for example, a serving access point can be selected in accordance with the maximum SINR measurement. Then, the access terminal 104 sends a data request broadcast message (DRC message) on a data request channel (DRC channel). A DRC message may comprise a requested data rate or, alternatively, a forward link quality indicator, for example, a measured SINR, error bit rate, error packet rate, and the like. Access terminal 104 may send a broadcast DRC message to a specific access point using a code that uniquely identifies a specific access point. As a rule, Walsh code is used as such a code. The characters of a DRC message are only processed by a logical OR (XOR) with a unique code. This XOR operation is called signal code coverage. Since each access point in the active set of the access terminal 104 is identified by a unique Walsh code, only selected access points that perform an XOR operation identical to the operation performed by the access terminal 104 with the correct Walsh code can correctly decode the DRC message.

The data to be transmitted to the access terminal 104 is received by the access network controller 110. After that, the access network controller 110 can send data to all access points in the active set of the access terminal 104 on the reverse link 112. Alternatively, the access network controller 110 may first determine which access point has been selected by the access terminal 104 as the serving access point, and then send data to the serving access point. Data is stored in a queue at the access point (s). The message of the paging system is then sent by one or more access points to the access terminal 104 via appropriate control channels. Access terminal 104 demodulates and decodes signals from one or more control channels to receive a paging system message.

For each interval of the direct communication channel, the access point can schedule data transmission to any of the access terminals that have received a paging system message. An exemplary method for scheduling transmission is described in US Pat. No. 6,229,795, entitled “System for allocating resources in a communication system”, issued to the present applicant. The access point uses speed control information received in the DRC message from each access terminal to efficiently transmit data over the forward link with the highest possible speed. Due to the fact that the data transfer rate may vary, the communication system operates in a variable speed mode. The access point determines the data rate at which to transmit data to the access terminal 104 based on the last DRC message received from the access terminal 104. In addition, the access point uniquely identifies the transmission to the access terminal 104 using a diversity code that is unique to this mobile station. This explode code is a long pseudo noise sequence, for example, an explode code defined in the IS-856 standard.

The access terminal 104 for which the data packet is intended receives and decodes the data packet. Each data packet is associated with an identifier, for example, a sequence number that is used by the access terminal 104 to detect missed or duplicate transmissions. In this case, the access terminal 104 transmits the sequence numbers of the missed data packets on the reverse link. Then, the access network controller 110, which receives data messages from the access terminal 104 through a communication channel between the access point and the access terminal 104, tells the access point which data blocks were not received by the access terminal 104. The access point then schedules the retransmission of such data packets.

When the communication channel between the access terminal 104 and the access point 100 operating in a variable data rate mode deteriorates below a predetermined reliability level, the access terminal 104 first tries to determine whether another access point in the variable data rate mode can maintain an acceptable data rate. If the access terminal 104 finds such an access point (eg, access point 102), re-pointing of the access point 102 to another communication channel occurs. The term re-pointing means the selection of a sector that is a member of the active set of the access terminal, where the sector is different from the currently selected sector. Data transfers continue from access point 102 in a variable data rate mode.

The aforementioned degradation of the communication channel may be caused, for example, by moving the access terminal 104 from the coverage area of the access point 100 to the coverage area of the access point 102, shielding, attenuation, and other well-known causes. Alternatively, when the communication channel between the access terminal 104 and another access point (eg, access point 102), which can reach a higher throughput than the used communication channel, becomes available, re-pointing to the access point 102 to another communication channel , and data transfers continue from access point 102 in a variable data rate mode. If the access terminal 104 cannot find an access point capable of operating in a variable data rate mode and maintaining an acceptable data rate, the terminal 104 enters a fixed data rate mode. In this mode, the access terminal transmits at the same speed.

Access terminal 104 evaluates communication channels with all access points as candidates for both variable bit rate and fixed bit rate modes, and selects an access point that gives maximum throughput.

The access terminal 104 will switch from a fixed data rate mode back to a variable data rate mode if the sector is no longer a member of the active set of the access terminal 104.

The fixed data rate mode described above and methods for transitioning to and from the fixed data rate mode are similar to those described in US Patent Application No. 6,205,129 entitled “METHOD AND APPARATUS FOR VARIABLE AND FIXED FORWARD LINK RATE CONTROL IN MOBILE RADIO COMMUNICATION SYSTEM”, owned by to the present applicant. Other fixed data rate modes and methods for transitioning to and from a fixed mode can also be considered and are within the scope of the invention.

Direct channel structure

Figure 2 illustrates the structure of the forward communication channel 200. It should be understood that the durations of time intervals described below, the lengths of micro frames, and the ranges of values are given by way of example only, and other durations of time intervals, frame lengths, and ranges of values can be used without violating the basic principles of a communication system. The term “micro frame” means a code diversity signal block having two possible meanings.

The forward link 200 is defined in terms of frames. A frame is a structure containing 16 time slots 202, each time interval 202 has a length of 2048 micro frames, which corresponds to a time interval of 1.66 ms, and accordingly a frame duration of 26.66 ms. Each time interval 202 is divided into two time intervals 202a and 202b, with control packets 204a, 204b transmitted in each time interval 202a, 202b. Each control packet 204a, 204b has a length of 96 micro frames, and is centered around the middle associated with the temporary half-interval 202a, 202b. The control packets 204a, 204b include a control channel signal coated with a code, for example, Walsh code with index 0. The forward channel of the Media Access Control Protocol (MAC) forms two packets that are transmitted immediately before and immediately by the control packet 204 of each time interval 202 A MAC is formed by no more than 64 coded channels that are orthogonally covered with 64-bit code, such as a Walsh code. Each encoded channel is identified by a MAC index, which is between 1 and 64 and identifies a unique 64-bit Walsh coverage code. A reverse power control channel (RPC) is used to adjust the power of the reverse link signals for each subscriber station. The RPC is allocated to one of the available MAC channels, for example, a MAC channel with a MAC index from 5 to 63. The reverse activity channel (RA channel) is used to control the data rate on the reverse communication channel for each of the subscriber stations by transmitting the reverse activity bitstream ( RAB stream). The RA channel is assigned to one of the available MAC channels, for example, MAC index 4. The forward channel traffic channel or control channel payload is sent in the remaining parts 208a of the first time half-interval 202a and the remaining parts 208b of the second time half-interval 202b. The traffic channel carries user data, and the control channel carries control messages and can also carry user data. The control channel is transmitted with a cycle, with a period of 256 intervals, at a data transfer rate of 76.8 kbps or 38.4 kbps. The term user data, also called traffic, refers to information other than service data. The term service data means information that enables the operation of elements of a communication system, for example, call support signaling, diagnostic and reporting information, and the like.

Packet channels and automatic retransmission request

As already discussed, the communication system may need to support both access terminals using the reverse communication channel in accordance with the IS-856 standard - traditional access terminals, and access terminals using the reverse communication channel in accordance with the described concept - new access terminals. To support such functionality in a direct communication channel, an additional channel, a packet providing channel (PG channel), is required. The PG channel can be provided by changing the modulation of one of the above MAC channels, for example, the RPC channel, from binary phase shift keying (BPSK) to quadratic phase shift keying (QPSK). When the second part of the reverse link interval is allocated to only one access terminal (see below), only one PG channel is needed, the primary PG channel.

Power control commands are modulated in the phase branch of the RPC channel assigned to the access terminal. The power control command information is binary, where the first value of the power control bit (“up”) instructs the access terminal to increase the transmit power of the access terminal by a first predetermined value, and the second value of the power control bit (“down”) instructs the access terminal to reduce the transmit power access terminal by a second predetermined value. As shown in FIG. 3, the “up” command is represented as “+1”; the “down” command is represented as “-1”. However, other values may be used.

The primary PG channel is transmitted through the quadrature branch of the RPC channel assigned to the access terminal. Information transmitted on the primary PG channel is ternary. As shown in FIG. 3, the first value is represented as +1, the second value is represented as 0, and the third value is represented as -1. The information has the following meanings, both for the access point and for the access terminal:

+1 means that permission to transmit a new packet is given;

0 means that permission to transmit a new packet is not given;

-1 means that permission has been given to transmit a previously transmitted packet (retransmission).

The alarm described above, in which the transmission of information with a value of 0 does not require signal energy, allows the access point to assign energy to the primary PG channel only when an instruction to transmit a packet is transmitted. Due to the fact that only one or a small number of access terminals are allowed to transmit on the reverse channel during the time interval, the primary PG channel requires very low power in order to provide information about the transmission on the reverse communication channel. Accordingly, sufficient power can be allocated to the primary PG channel in order to guarantee reliable reception of the primary PG channel by access terminals without unduly disrupting power distribution. Accordingly, the effect on the distribution method of RPC power is minimized. A method for distributing RPC power is disclosed, for example, in pending US patent application No. 09 / 669,950, entitled “Method and apparatus for allocation of power to base station channels” of September 25, 2000, and in a pending patent application US No. 10 / 263,976, entitled “Power Allocation for Power Control Bits in Cellular Network”, dated October 2, 2002, both belong to the present applicant. Moreover, it is required that the access terminal perform the ternary quadrature flow decision only when the access terminal is waiting for a response to the data transfer request or when the access terminal has incomplete data transfer. However, it should be understood that the choice of ternary values is a matter of choice, and values other than those described above may be used.

The access terminal receives and demodulates the RPC / primary PG channel from all access points from the active set of the access terminal. Accordingly, the access terminal receives primary PG channel information transmitted in the quadrature RPC / primary PG channel for each access point from the active set of the access terminal. The access terminal can filter the energy of the received information of the primary PG channel on a single update interval and compare the filtered energy with many threshold values. Using the appropriate choice of threshold values, access terminals that are not given permission to transmit decode the value of the primary PG channel as 0 with high probability.

Further, the information contained in the primary PG channel is used as a means of automatically requesting a retransmission.

When the transmission of the packet from the access terminal by the reverse access channel is received only by the serving access point, the serving access point generates and transmits permission to transmit a new packet in response to a request from the access terminal to transmit the packet when the previous packet from the access terminal was received correctly. In this case, such information in the primary PG channel serves as a notification (ACK). The serving access point generates and transmits permission to retransmit the previous packet as a response to a request from the access terminal to transmit the packet if the previous packet from the access terminal was received incorrectly. Such information on the primary PG channel serves as a negative notification (NACK). Thus, a separate ACK / NACK channel is not required.

Alternatively, the transmission of the packet on the reverse channel from the access terminal may be received by multiple access points.

When a non-serving access point receives and decodes the reverse link from the transmitting access terminal, the non-serving access point provides information on whether or not user data has been successfully decoded at the serving access point. The serving access point then sends an ACK / NACK to the access terminal on the primary PG channel.

Alternatively, access point (s) that have received useful information send useful information to the centralized element to perform soft-decision decoding. The centralized element then notifies the serving access point of whether the decoding of the payload was successful. The serving access point then sends the ACK / NACK to the access terminal on the primary PG channel.

Alternatively, before decoding the reverse link, the non-serving access point can autonomously send ACK / NACK to the access terminal via the primary PG channel. Thus, it is possible that the access terminal will receive conflicting information on the primary PG channel, for example, due to the fact that some access points could not correctly receive the transmission of the access terminal, information on the primary PG channel was deleted or incorrectly received, or for other known reasons . Accordingly, information transmitted in response to transmission on the reverse communication channel on the primary PG channel is interpreted in a different way when transmitted by a serving or non-serving access point. Therefore, from the point of view of the access network, it does not matter which access point receives the access terminal transmission, when the access terminal receives information on the primary PG channel, interpreted as ACK from any access point, it transfers a new packet to the next transmission resolution, although the serving terminal access can send permission to re-transmit the previously sent packet.

Because the access terminal makes a ternary decision on the primary PG channel received from the serving access point and the binary decision on the primary PG channel received from the access point, the access terminal can use different threshold values for ternary decision and binary decision.

When the second part of the reverse link interval is allocated to only one access terminal (see below), the PG channel described above provides satisfactory information. However, when the second part of the reverse communication channel interval is allocated to a plurality of access terminals, additional information is required, namely, which access terminal that has received transmission permission should transmit, in which partition of the second part of the reverse communication channel interval. Such information may be provided by an auxiliary PG channel.

The structure of the auxiliary PG channel is exactly the same as that of the above-described PG channel, except that the auxiliary PG channel has a different MAC index. Returning to FIG. 3, the auxiliary PG channel information is transmitted in both phase and quadrature branches. This information is interpreted along with information extracted from the PG channel as follows:

- when the PG channel informs the access terminal that permission to transmit the packet has not been received, the auxiliary PG channel is ignored,

- when the PG channel informs the access terminal that permission to transmit a new packet or permission to transmit a previously sent packet (retransmission) is received, then:

0 means that the access terminal must use the entire second part of the interval of the reverse link;

any of the four remaining values identifies one of the four partitions of the second part of the interval of the reverse communication channel.

Thus, the signaling described above can support four partitions of the second part of the reverse link interval. Additional auxiliary PG channels may be added if more partitions are required.

PG channels, i.e. MAC indices, may be allocated to an access terminal before accessing an access terminal to a communication system. Alternatively, the PG channel may be allocated to the access terminal, and the auxiliary PG channel may be determined by the access terminal by the MAC index of the PG channel, for example, by adding a predetermined offset to the PG channel.

Reverse Activity Channel

As described above, the communication system in accordance with the IS-856 standard uses a reverse activity channel to control the data rate on the reverse communication channel for each subscriber station by transmitting a reverse activity bitstream (RAB stream). This reverse activity channel is sufficient only if a small number of terminals transmitting at intervals designated for TDMA operate in a communication system. However, to support both traditional access terminals and new access terminals transmitting at intervals assigned to TDMA, an additional channel in the forward link is required.

In order to support the reverse link data rate for new access terminals transmitting at TDMA assigned intervals, it may be necessary for the reverse activity channel to support the transmission of a value that controls the data rate requiring more than one bit. Because of this, it may be desirable not to overly change the structure of the forward communication channel, the additional reverse activity channel may have the same structure as the traditional reverse activity channel, but a different MAC index may be assigned to it. Because such a reverse activity channel supports the transmission of only one bit, a multi-bit value can be transmitted through several transmitting instances of the reverse activity channel.

The forward link 200 described above is a modification of the forward link in a communication system in accordance with the IS-856 standard. It is believed that such a modification has a lesser effect on the structure of the direct communication channel and, accordingly, requires fewer changes to the IS-856 standard. However, it should be understood that such a doctrine is applicable to various structures of the direct communication channel. Thus, for example, the channels of the forward communication channel described above can be transmitted not sequentially, but simultaneously. In addition, any structure of the direct communication channel that makes it possible to transmit information available in the PG, auxiliary PG and RA channel, for example, separate PG and ACK / NACK encoded channels, a new RA channel, different from the traditional RA channel, can be used.

Reverse link

As described above, the quality and efficiency of data transmission depends on the state of the channel between the source terminal and the destination terminal. Channel conditions are dependent on interference and path loss, which are time-dependent. Thus, the performance of the reverse link can be improved using interference suppression techniques. On the reverse communication channel, all access terminals in the access network can simultaneously transmit on the same frequency (one set of reusable frequencies), or many access terminals in the access network can on the same frequency (more than one set of reused frequencies). It should be noted that the reverse link described here can use any frequency reuse. Thus, any transmission by the access terminal over the reverse link is subject to several sources of interference. The most dominant interference are:

- the transmission of service channels with multiple access with code division multiplexing from other access terminals both from the same cell and from other cells;

- transmission of user data with multiple access, code division multiplexing by access terminals from the same cell;

- transmission of user data with multiple access, code division multiplexing by access terminals from other cells.

Studies of reverse channel performance in code division multiple access (CDMA) communication systems show that eliminating interference in the same cell can lead to a significant improvement in data quality and efficiency. Interference in the same cell in communication systems using CDMA, for example, in communication systems in accordance with the IS-856 standard, can be reduced by limiting the number of access terminals that can simultaneously transmit over the reverse communication channel.

Due to the existence of two operating modes, that is, a limitation on the number of simultaneously transmitting access terminals and allowing all terminals to transmit simultaneously, the access network must notify the terminals of which mode should be used. The notification is transmitted to the access terminals at periodic intervals, for example, in a predetermined part of the forward communication channel, for example, each control cycle of the channel. Alternatively, the notification is transmitted to the access terminals only when changed, using a broadcast message on a direct communication channel, for example, on a reverse power control channel.

When the system operates in a restricted mode, the direct packet providing communication channel described above can be used to enable or disable the transmission of access terminals requesting permission to transmit.

Interference in the same cell can also be reduced by using a traffic channel and time-division multiple access service channels on the reverse link, and by scheduling which access terminals requesting the transmission are allowed to transmit user data or traffic in the time interval of the reverse link communication, for example, in a frame, a time interval, or in any other time interval supported by the communication system. Scheduling may take into account the entire access network, and may be performed by a centralized element, such as an access network controller 110. This scheduling method minimizes interference because the terminals transmit in neighboring sectors of the cell. Alternatively, scheduling may take into account only a part of the access network containing only one access point, and may be performed either by a centralized element or by a decentralized element, for example, an access point controller. This planning method only reduces interference in the same cell. Moreover, a combination of these two methods can be used, when for several access points, but not for the entire access network, planning is carried out by one element.

It should be clear that the number of access terminals that are allowed to transmit in the time interval affects the interference in the reverse communication channel, and accordingly, the quality and class of the provided data services (QoS) for the reverse communication channel. Thus, the number of access terminals that are allowed to transmit is a design criterion. Accordingly, such an amount can be adjusted by a planning method in accordance with changing conditions and / or QoS requirements.

Additional improvements can be achieved by reducing interference from other cells. Interference from other cells in the process of transmitting user data is suppressed by opportunistic transmission, control of transmission power and transmission rate of user data for each access terminal within a multi-sector cell. “Opportunistic transmission” (and multi-user diversity) means scheduling transmissions of access terminals at time intervals in which a certain tolerance threshold is exceeded. A time interval can be considered acceptable if the metric determined in accordance with the instantaneous quality metric for the reverse communication channel in the time interval, the average quality metric for this reverse communication channel, and a function that makes it possible to differentiate users (such as the impatience function described below) , exceeds the tolerance threshold. The method makes it possible to transmit user data by the access terminal at a lower transmit power and / or complete the transmission of the packet using fewer time slots. Less transmit power and / or completion of packet transmission using fewer time slots results in less interference from transmitting access terminals in sectors of a multi-sector cell, and thus less total interference from other cells for access terminals in neighboring cells. Alternatively, channel states above average allow the terminal to use the available power for transmission at a higher data rate, thereby causing the same interference in other cells as that caused by an access terminal using the same available power to transmit with lower data rates at inappropriate time intervals.

In addition to reducing interference in the reverse link, path loss and changing path loss can be used by multi-user diversity to increase throughput. “Multi-user diversity” is the result of channel state diversity across access terminals due, for example, to different locations experiencing different shielding and attenuation as a function of time. Diversity in channel states among user terminals makes it possible to schedule access terminal transmissions at time intervals during which channel states for the access terminal satisfy a certain criterion, which makes it possible to transmit at lower power or higher data rates, thereby improving the spectral transmission efficiency on the reverse communication channel. Such criteria include the quality metric of the reverse link of the access terminal, and better considered in conjunction with the average quality metric of the reverse link of the access terminal.

The scheduler design can be used to control the QoS of access terminals. Thus, for example, by mixing the scheduler in the direction of a subset of access terminals, the subset can be allocated a transmission priority, although the validity shown by these terminals may be lower than the validity shown by terminals not belonging to this subset. It should be understood that a similar effect can be achieved by using the impatience function described below. The term subset means a set whose members are at least one, but not all members of another set.

Even with the opportunistic transmission method, the transmitted packet may be mistakenly received and / or deleted by the access point. The term deleted means the inability to determine the contents of the message with the required reliability. This erroneous reception is a consequence of the inability of the access terminal to accurately predict the quality metric of the reverse communication channel of the access terminal due to interference from other cells. The interference from other cells is difficult to quantify in communication systems in which transmissions from access terminals from sectors belonging to different multi-sector cells are not synchronized, short and not correlated.

Automatic retransmission request (ARQ) techniques are often used to suppress incorrect channel estimates and provide interference averaging. ARQ methods detect missing or erroneously received packet (s) at the physical layer or at the link layer and request retransmission of these packets from the transmitting terminal.

Hierarchical partitioning is a way to organize communication protocols for well-defined encapsulated data blocks between otherwise separated processing elements, that is, layers. Protocol layers are implemented both in access terminals and in access points. According to the Open Systems Interconnection Model (OSI), the L1 protocol layer provides for the transmission and reception of radio signals between the base station and the remote station, the L2 layer provides for the correct transmission and reception of signaling messages, and the L3 layer provides for the exchange of signaling messages for the communication system. The L3 layer starts and ends signaling messages in accordance with the semantics and synchronization of the communication protocol between access terminals and access points.

In IS-856 communication systems, the signaling layer L1 of the air interface is called the physical layer, L2 is called the link access control layer (LAC) or media access control (MAC) layer, and L3 is called the signaling layer. Above the signal level are additional levels, which are numbered L4-L7 according to the OSI model, and are called the transport layer, session layer, presentation layer, and application layer. The physical level of ARQ is disclosed in US Patent Application No. 09 / 549,017, entitled “Method and Apparatus for Quick Re-transmission of Signals In A Communication System” dated April 14, 2000, issued to the present applicant. An example of an ARQ link layer method is a radio channel protocol (RLP). The RLP protocol belongs to the class of error control protocols known as ARQ protocols based on no acknowledgment (NAK). One such RLP protocol is described in document TIA / EIA / IS-707-A.8, entitled “DATA SERVICE OPTIONS FOR SPREAD SPECTRUM SYSTEMS: RADIO LINK PROTOCOL TYPE 2”, hereinafter referred to as RLP2. Transmissions of both original and retransmitted packages may be opportunistic.

Reverse Link Transmission

The transmission of user data on the reverse link from conventional access terminals uses code division multiple access (CDMA), such as CDMA in accordance with the IS-856 standard.

New access terminals may use various multiple access methods for the reverse link in accordance with the options available in the communication system. First, new access terminals can use CDMA used by traditional access terminals, for example, CDMA in accordance with the IS-856 standard.

In addition, the communication system may be able to operate a reverse communication channel, designed mainly for time division multiple access (TDMA). Such operation is possible when dividing the reverse communication channel into intervals, and the communication of each of the intervals with CDMA or TDMA. A control element in an access network, for example, an access network controller 110, makes a decision determining the assignment of a sequence of CDMA and TDMA slots. The decision is made in accordance with the state of the reverse communication channel for a particular access terminal, the number and activity of traditional access terminals, and other design criteria in the communication system. The reverse link state can be set in accordance with the erasure rate for the DRC channel. Design criteria may include, for example, whether a particular terminal is in a state of transferring a call from one base station to another while a user is moving, loading a reverse link, and other criteria known to one skilled in the art. Obviously, the distribution may include only the intervals associated with one of the multiple access methods.

Then, the control element in the access network informs the access terminals of the destination by sending the distribution to all access terminals of the access network. Alternatively, the assignment is only transmitted to new access terminals. The assignment is transmitted in periodic intervals, that is, in a predetermined part of the direct communication channel, for example, each control cycle of the channel. Alternatively, the assignment is transferred to the access terminals only when changed using a broadcast message in a direct communication channel, for example in a control channel. The number of bits in a message (indicator bits) depends on the number of different sequences.

The new terminals receive the destination information and, if the autonomous ability to choose between CDMA and TDMA functionality is not specified, go into multiple access specified in the destination information. If the access terminal is given the opportunity to choose between CDMA and TDMA functionality, the new access terminal autonomously makes a decision in accordance with the design criteria of the communication system. Such criteria may include, for example, the free resources of the power amplifier, the quality metric of the forward communication channel, the presence of a certain terminal in a state of transferring a call from one base station to another while the user is moving, the quality metric of the reverse communication channel, the amount of data to be transmitted , impatience function value, QoS requirements, and other well-known design criteria. Thus, for example, a new access terminal, whose energy potential of the communication line allows transmission on the reverse communication channel at a speed above a threshold value, can use TDMA; otherwise, new access terminals may use CDMA. Moreover, new access terminals capable of using TDMA, but having too small a data packet size for transmission at high data rates, can choose CDMA. Alternatively, ATs may choose CDMA for low latency applications.

Reverse communication channels

As discussed above, the traditional access terminals operate in accordance with the IS-856 standard, respectively, the waveform of the reverse communication channel for conventional terminals is identical to the waveform for the reverse communication channel according to the IS-856 standard, and is not described in further detail below.

In addition, new access terminals using code division access, such as CDMA in accordance with IS-856, use the waveform of the reverse link identical to the waveform of the reverse link according to IS-856.

An exemplary waveform of the reverse link for a new access terminal operating in the TDMA interval is shown in FIGS. 4a-c. It should be clear that the given time durations, lengths of micro frames, ranges of values are given only as an example, and other durations of time intervals, frame lengths, ranges of values can be used without violating the basic principles of the communication system.

Reverse communication channel 400 is defined in terms of intervals 402. An interval is a structure containing a predetermined number of time intervals 404. As shown in FIG. 4A, an interval contains m time intervals, however, the number of time intervals is a design issue; accordingly, any number of time intervals can form an interval. Each time interval 404 (1), ..., 404 (m) is divided into two parts 406, 408. The first part 406 contains overhead channels 412-418, and an optional traffic channel, followed by an additional overhead channel 420.

Service channels of the reverse communication channel comprise: control channel 412, data request channel 414, notification channel 416 (ACK), packet request channel (PR) 418. Additionally, a traffic channel followed by a reverse rate indication channel (RRI), collectively denoted by reference 420, may also be included in the first part 406.

The second part 408 is further divided into subsections 410, each subsection 406 carries a traffic channel and an accompanying reverse speed indication (RRI) channel 422 for the access terminal. As shown in FIG. 4A, there are n subsections 410 in the second part 408 (1) of the first time interval 404 (1); accordingly, n different access terminals can transmit on the second part 408 (1) of the interval 404 (1); there are l subsections 410 in the second part 408 (m) of the m- th time interval 404 (m); accordingly, n different access terminals can transmit in the second part 408 (m) of the interval 404 (m). The access network, in accordance with the design of the scheduler, can vary the number of subsections 410. One subsection means that the entire second part of the interval is used by one terminal. The additional traffic channel and the accompanying RRI channel provided in subsections 410 may use TDM, OFDM, CDM, or any other multiplexing format.

Fig. 4b illustrates a specific TDMA slot 402. A TDMA slot contains one time slot 404. The time slot 404 has a length of 2048 micro frames, which corresponds to a 1.66 ms time slot. Each time interval is divided into two parts 406, 408, each part is equal to half the time interval. Due to the fact that the second part 408 is not additionally divided, the second part 408 corresponds to the first subsection 410.

Service channels, as described above, differ in different codes, for example, by encoding with different Walsh codes, and are concentrated in the first part 406. An optional traffic channel, accompanied by a reverse speed indication channel (RRI), collectively denoted by reference 420, can also be included in the first part 406. The RRI channel is embedded in the traffic channel, and the resulting structure 420 differs from the service channels in a different code, for example, by encoding with a different Walsh code. Accordingly, the traffic channel and the RRI channel 420 are called the CDM traffic channel, corresponding to the CDM / RRI channel. Alternatively (not shown), the RRI channel is not embedded in CDM traffic. Accordingly, the CDM traffic channel and the RRI channel are different by covering each with a unique code.

An additional traffic channel 422 (T) and an accompanying speed indication (RRI) accompanying return channel 422 (RRI) are provided in the second time half-interval 408. As shown in FIG. 4B, the traffic channel 422 (T) and the accompanying RRI channel 422 (RRI) are multiplexed with time division and are called the TDM traffic channel, corresponding to the TDM / RRI channel.

Although not shown, the additional traffic channel and the accompanying RRI channel provided in the second time slot 408 may use OFDM, CDM, or any other modulation format (not shown). In addition, as described below, the additional traffic channel and the accompanying RRI channel provided in the second half-time interval 408 may use different multiplexing formats, for example TDM and OFDM, depending on the data rate.

4C illustrates the waveform of the reverse link for an access terminal operating in the TDMA interval but not transmitting data in the second half-interval 408. As shown, the overhead channels 406-418 and the optional CDM traffic channel / CDM RRI channel 420 are still transmitted during the first half-interval 406, and energy is not transmitted in the second half-interval 408.

Accordingly, to embed user data in an interval allocated by TDMA, the new access terminal may use three different protocols (modes) for multiplexing user data in such an interval:

- embedding user data in the first part of the interval using code division multiplexing (CDM);

- embedding user data in the second part of the interval using time division multiplexing (TDM) or orthogonal frequency division multiplexing (OFDM); and

- embedding user data in the first part of the interval using CDM and in the second part of the interval using TDM / OFDM.

FIG. 4B illustrates the waveform of the reverse link for a new access terminal operating in the CDMA interval and transmitting user data in both time half-intervals 406, 408. As shown, the overhead channels 412-418 and the optional CDM traffic channel / CDM RRI channel 420 are transmitted to during the first half-interval 406. An additional CDM channel 422 is transmitted during the second half-interval 408.

Although not shown in FIG. 4D, the new access terminal may use the CDM traffic channel, that is, embed user data in an interval intended for CDMA using CDM using:

- embedding user data in the first part of the interval 406;

- embedding user data in the first part of the interval 408; and

- embedding user data in the first part of the interval 406, as well as in the second part 408.

The data transmitted in the CDM part and the TDM / OFDM part of the time interval may contain data related to the same amount of information, for example video. In addition, the base video stream can be transmitted in the CDM part of the time interval and the improved video stream in the TDM / OFDM part of the time interval; accordingly, an acceptable video can still be obtained if the terminal cannot transmit in the second half of the time interval. Alternatively, each half may contain data related to different volumes of information. Thus, for example, voice data can be transmitted in the CDM part of the time interval, and video can be transmitted in the TDM / OFDM part of the time interval.

Control channel

In one implementation, pilot channel 412 is used to evaluate the quality of the reverse link. In addition, pilot channel 412 is used to coherently demodulate the channels transmitted in the first time half-interval 406. The pilot channel 412 contains unmodulated symbols with a binary value of '0'. Turning to FIG. 5, unmodulated symbols are provided to block 510 (1), which maps binary symbols to modulated symbols in accordance with the selected modulation. For example, when the selected modulation is binary phase shift keying (BPSK), the binary symbol '0' is mapped to a modulated symbol value of +1, and the binary symbol '1' is mapped to a modulated symbol value of -1. The displayed symbols are covered by the Walsh function generated by block 510 (2) in block 510 (4). Then, Walsh-covered characters are provided for further processing.

Data Request Channel

The data request channel 414 is used by the access terminal to notify the access network of the selected serving sector and the requested data rate on the forward traffic channel. The requested data rate on the forward traffic channel includes, for example, a four-bit DRC value. With reference to FIG. 5, DRC values are provided to block 506 (2), which decodes a four-bit DRC value in order to obtain biorthogonal codewords. The DRC codeword is provided to block 506 (4), which repeats each codeword twice. Repeated codewords are provided to block 506 (6), which maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are provided to block 506 (8), which covers each symbol with a code, for example, the Walsh code generated by block 506 (10), in accordance with DRCCover identified by index i . Then, each resulting Walsh micro-frame is provided to block 506 (12), where the Walsh micro-frames are covered with a different code, for example a different Walsh code, generated by block 506 (14). Walsh-covered symbols are then provided for further processing.

ACK channel

ACK channel 416 is used by the access terminal to inform the access network that user data transmitted over the forward traffic channel has been successfully received or not. The access terminal transmits the ACK bit of the channel in response to each slot of the forward traffic channel that is associated with the detected preamble intended for the access terminal. The channel ACK bit is set to +1 (ACK) if the forward traffic channel packet was received successfully; otherwise, the channel ACK bit is set to -1 (NAK). Forward channel user data is considered successfully received if the CRC value protecting the transmitted user data is identical to the CRC value calculated from the decoded user data. With reference to FIG. 5, the channel ACK bit is repeated in block 508 (2) and provided to block 508 (4). Block 508 (4) maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are then provided to block 508 (6), which covers each symbol with the Walsh code generated by block 508 (8). Walsh-covered characters are then provided for further processing.

Package Ready Channel

Each access terminal wishing to transmit informs the serving sector that there is user data to transmit at future intervals and / or that transmission at future intervals is timely. An interval is considered timely if the instantaneous quality metric for the interval of the reverse communication channel exceeds the average quality metric for this reverse communication channel, modified by the level of timeliness determined in accordance with additional factors depending on the design of the communication system, exceeds a threshold value.

The quality metric for the reverse communication channel is determined in accordance with the reverse control channel, for example, according to equation (1):

(1)

(one)

where Tx_Pilot ( n ) is the power at which the control channel is transmitted during the n-th interval; and

Filt_Tx_Pilot ( n ) is the power of the filtered pilot signal, filtered over the last k intervals, calculated in the nth interval. The filter time constant, expressed in intervals, is determined to ensure adequate averaging of the reverse communication channel.

Accordingly, equation (1) shows how much better or worse the instantaneous return channel compared to the average return channel. The access terminal measures Tx_Pilot ( n ) and Filt_Tx_Pilot ( n ), and calculates the quality metric in accordance with equation (1) for each interval. The calculated quality metric is then used to evaluate the quality metrics for a predetermined number of intervals in the future. The predetermined number of intervals may be 2. The method for such a quality assessment is described in detail in US Patent Application No. 09 / 974,933, entitled “Method and Apparatus for Scheduling Transmissions Control in a Communication System,” dated October 10, 2001, issued to the present applicant.

The method for evaluating the quality metric for the reverse communication channel described above is provided only as an example. Thus, other methods may be used. For example, access terminals may provide information about the control channel and the transmission power levels of the traffic channel to the access point, which then uses this information to determine timely transmission intervals.

Factors that determine the level of timeliness include, for example, the maximum acceptable transmission delay t (from the arrival of the packet to the access terminal to the transmission of the packet), the number of packets in the queue at the access terminal l (transmission queue length), and the average throughput of the reverse communication channel th . The factors mentioned above determine the impatience function I ( t, l, th ). The impatience function I ( t, l, th ) is determined in accordance with the desired influence of the input parameters. For example, to immediately transmit the first packet arriving for transmission to the access terminal queue, the impatience function is small, but the value increases if the number of packets in the queue of the access terminal exceeds a threshold value. The impatience function reaches its maximum when the maximum acceptable transmission delay is reached. The queue length parameter and the transmission bandwidth parameter affect the impatience function in a similar way.

The use of the three parameters mentioned above as input parameters for the impatience function is provided for explanatory purposes only; any number or even other parameters can be used in accordance with the constructive consideration of the communication system. In addition, the function of impatience may be different for different users, thereby providing differentiation of users. Moreover, functions other than impatience can be used to differentiate users. Thus, for example, an attribute may be assigned to each user in accordance with the user's QoS. The attribute itself can serve instead of the impatience function. Alternatively, the attribute can be used to modify the input parameters of the impatience function.

The impatience function I ( t, l, th ) can be used to modify the quality metric in accordance with equation (2):

(2)

(2)

The relationship between the values calculated by equation (2) and the threshold value T _j can be used to determine timeliness levels. A set of suitable levels of timeliness is given in table 1 for an example. It should be understood that other meanings and different definitions of levels of timeliness can be used instead of those given.

Table 1 Timeliness level Definition 0 No data to transfer one There is data to transmit 2 There is data to transmit, channel status “GOOD” or impatience to transmit “HIGH” 3 There is data to transmit, channel status “VERY GOOD” or impatience to transmit “VERY HIGH”

The appropriate level of timeliness is encoded and transmitted over the PR channel. The PR channel is transmitted if the timeliness level is different from zero, that is, “no data to transmit” should be indicated. The four levels of timeliness described above can be represented as two information bits. It is necessary that the PR channel is received by the access point with high reliability because any error in receiving the PR channel can lead to possible planning for the access terminal that does not have the requested user data transmission or reports a low level of timeliness. Alternatively, such an error can lead to a failure in planning for the access terminal, which reported a high level of timeliness. Accordingly, it is necessary that two information bits be delivered with sufficient reliability.

As described above, the timely transmission interval is meant because both the access point and the access terminal have information about a predetermined number of intervals in the future for which the level of timeliness has been estimated. Due to the fact that the timing distribution for the access point and access terminals is synchronized, the access point can determine which interval is the timely transmission interval for which the transmitting terminal reported the timeliness level. However, it should be understood that another systematization may be applied in which the timely transmission interval is variable and is explicitly transmitted to the access point.

The PR value of channel 418, in accordance with the concepts described above, is expressed as a two-bit value. With reference to FIG. 5, a PR value is provided to block 512 (2), which encodes a two-bit value to obtain a codeword. The codeword is provided to block 512 (4), which repeats each codeword. The repeated codeword is provided to block 512 (6), which maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are then provided to block 512 (8), which covers each symbol with the Walsh code generated by block 512 (10).

CDM traffic channel

The CDM traffic channel 420 is a variable rate channel and is packet based. User data packets for the access point are transmitted at data rates selected from, for example, the following set of data rates: 9.6, 19.2, 38.4, 76.8 and 153.6 kilobits per second (kbps).

With reference to FIG. 5, data to be transmitted (data bits) are divided into blocks of a predetermined size and provided to block 504 (2). Block 504 (2) may comprise a turbo encoder. The output of block 504 (2) consists of code symbols. Code symbols are sealed by block 504 (4). In one implementation, block 504 (4) comprises apparatus for temporarily compressing the channel pulse signals with bit inversion. Depending on the data rate and the encoder coding rate, the sequence of compressed code symbols is repeated in block 504 (6) as many times as necessary to achieve a fixed modulation symbol rate, and is provided to block 504 (8). Block 504 (8) is provided with the CDM RRI channel symbols and embeds the CDM RRI channel symbols in the CDM symbols of the traffic channel. Embedded symbols are provided to block 504 (10), which maps binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are then provided to block 504 (12), which covers each symbol with the Walsh code generated by block 504 (14). The resulting microframes are provided for further processing, which is described in detail below. The CDM packets of the traffic channel / RRI channel can be transmitted in one or a plurality of time intervals, depending on the user relationship data-to-control information, the size of the packet, and specified data is determined.

CDM reverse speed indication channel

The CDM RRI channel 420 provides an indication of the packet type of the reverse link. An indication of the type of packet is provided to the access point along with information that helps the access point in determining whether soft decisions from the currently received packet can be softly combined with soft decisions from previously received packets. Soft combining takes advantage of the energy values at the bit positions received from previously received and decoded packets (soft decision values). The access point will determine the bit values (hard decision) of the packets by comparing the soft decision values with the threshold value. If the energy corresponding to the bit is greater than the threshold value, the first value is assigned to the bit, for example, '1', otherwise the second value is assigned to the bit, for example, '0'. Then, the access point ascertains whether the packet was decoded correctly, for example, by performing a CRC check, or by any other equivalent or suitable method performed after decoding the packet. If this check fails, then the package is considered deleted. However, the access point retains the soft decision values (if the number of retransmission attempts for the packet is less than the allowed maximum number of attempts), and when the access point receives the soft decision values for the current packet, it can combine the stored soft decision values with the soft decision values for the current package and compare the combined values of the soft solution with a threshold value.

Combination methods are well known, and accordingly, there is no need to consider them. One suitable method is described in detail in US patent No. 06,101,168, entitled "Method and Apparatus for Time Efficient Re-transmission Using Symbol Accumulation", issued to the present applicant.

However, in order to intelligently gently combine the packets, the access terminal must know that the packets contain information that can be combined, as well as a combination method. The set of RRI values is determined according to the combination method. The RRI channel may be similar to the RRI channel conforming to the IS-856 standard. With reference to FIG. 5, an RRI value represented by, for example, 3 bits, is provided to block 502 (2), which encodes 3 bits, in order to obtain a 7-bit codeword. An example of coding is given in table 2.

table 2 RRI symbol RRI codeword 000 0000000 001 1010101 010 0110011 011 1100110 one hundred 0001111 101 1011010 110 0111100 111 1101001

The codeword is provided to block 502 (4), which repeats each codeword. Repeated codewords are provided to block 502 (6), which provides a codeword to block 504 (8) for embedding traffic in the CDM channel. Blocks 502 (8), 502 (10) and 502 (12) are not used.

Alternatively, the codeword is provided to block 502 (4), which repeats each codeword. Repeated codewords are provided to block 502 (6), which provides a codeword to block 504 (8), which maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are then provided to block 504 (10), which covers each symbol with the Walsh code generated by block 504 (12). The resulting microframes are provided for further processing, which is described in detail below.

TDM traffic channel

The TDM channel 422 (RRI) of the traffic is a variable rate channel and is packet based. User data packets for the access point are transmitted at data rates selected from, for example, the following set of data rates: 76.8, 153.6, 230.4, 307.2, 460.8, 614.4, 921.6 and 1843.2 kbps. The data to be transmitted (data bits) is divided into blocks of a predetermined size and provided to block 504 (2). Block 504 (2) may comprise a turbo encoder with a 1/5 coding rate. The output of block 504 (2) consists of code symbols. Code symbols are sealed by block 504 (4). Block 504 (4) may comprise apparatus for temporarily compressing the pulse signals of a channel with inverting bits. Depending on the data rate and the encoder coding rate, the sequence of compressed code symbols is repeated in block 504 (6) as many times as necessary to achieve a fixed modulation symbol rate, and is provided to block 504 (8). Block 504 (8) transmits the symbols to block 504 (10), which maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are provided to block 504 (12), which covers each symbol with the Walsh code generated by block 504 (14), and the resulting microframes are provided for further processing, which is described in detail below.

As part of the processing, code symbols are transformed into modulation symbols. The traffic channel TDM modulation symbols are then time division multiplexed with RRI channel microframes. However, the size of the TDM channel does not necessarily correspond to the size of the symbols obtained by combining the RRI channel microframes and the TDM channel modulation symbols of the traffic packet. Accordingly, the micro frames representing the original packet symbols are divided into sub-packets, which are inserted into the TDM channel and transmitted. The method for transmission, incremental redundancy, is described in pending US patent application No. 09 / 863,196, entitled “ENCHANCED CHANNEL INTERLEAVING FOR INCREASED DATA THROUGHPUT”, dated May 22, 2001, owned by the present applicant.

The transmission of sub-packets described above is described with reference to Table 3, which illustrates the parameters of the packet. Data rates and associated packet parameters are provided for example only, respectively, other data rates and associated packet parameters may be considered.

Table 3 Data rate (kbps) Data bits Code Symbols Modulation type Modulation Symbols RRI Microframes Modulation symbols in TDM channel 76.8 256 1280 QPSK 640 384 1280 153.6 512 2560 QPSK 1280 192 1664 230.4 768 3840 QPSK 1792 128 1792 307.2 1024 5120 QPSK 1856 96 1856 460.8 1536 7680 QPSK 1920 64 1920 614.4 2048 10240 QPSK 2560 64 1920 921.6 3072 15360 8-PSK 3840 64 1920 1228.8 4096 20480 8-PSK 5120 64 1920 1843.2 6144 30720 16-qam 7680 64 1920

Considering a data rate of 1843.2 kbps, the data to be transmitted is divided into blocks of 6144 bits. Encoding at a speed of 1/5 leads to 6144 x5 = 30720 code symbols. 16-QAM modulation is used, which means that every four code symbols result in one modulation symbol. Thus, 30720 code symbols result in 30720/4 = 7680 modulation symbols. Because the TDM channel contains two half-time slots, the size of the TDM channel is 1024 micro frames per slot. Due to the fact that the number of RRI micro frames in the time interval is 64, there is room for 2x (1024-64) = 1920 modulation symbols in the TDM channel.

The first sub-packet is formed by inserting the first 1920 modulation symbols from the total number of 7680 modulation symbols into the TDM channel. Since the sub-packet contains all the information necessary to recover data bits from the packet, if the transmission is successful, that is, the sub-packet is decoded; the next packet is transmitted. If the transfer fails, the next sub-packet is generated. In one implementation, the next sub-packet is formed by inserting the second 1920 modulation symbols from a total of 7680 modulation symbols into the TDM channel. This method is repeated until the packet data bits are successfully decoded, or until a predetermined number of transmissions or retransmissions of sub-packets are reached.

In order to enable the access point to softly combine the sub-packets transmitted in this way with incremental redundancy (HARQ), a sub-packet index is assigned to each sub-packet. The sub-packet index is transmitted on the reverse TDM speed indication channel, as described below.

The term sub-package was used in the previous description for consulting purposes, namely, to explain the concept of incremental redundancy. Because this differentiation is mainly semantic, the term package will be used in all cases, except when it is necessary to use the term sub-package for a clear understanding.

Reverse TDM Speed Indication Channel

The TDM RRI channel 422 (RRI) serves the same purposes as the CDM RRI channel. Accordingly, the TDM RRI channel provides an indication of the type of packet of the reverse communication channel (for example, payload size, coding rate, modulation, and the like), as well as a sub-packet index that is used for incremental redundancy (HARQ).

To provide the desired indication, the RRI contains 5 bits of information. With reference to FIG. 5, an RRI value is provided to block 502 (2), which biorthogonally encodes 5 bits to obtain a codeword. The codeword is provided to block 502 (4), which repeats each codeword. Repeated codewords are provided to block 502 (6), which maps the binary symbols to modulation symbols in accordance with the selected modulation. The mapped symbols are then provided to block 502 (8), which covers each symbol with the Walsh code generated by block 502 (10), and the resulting microframes are provided for further processing, which is described in detail below.

Table 4 Meaning of the code word RRI Packet rate Subpackage index 0.1 76.8k 1,2 2,3 153.6k 1,2 4,5 230.4k 1,2 6.7 307.2k 1,2 8.9 460.8k 1,2 10,11,12 614.4k 1,2,3 13,14,15 921.6k 1,2,3 16,17,18,19 1228.8k 1,2,3,4 20,21,22,23 1843.2k 1,2,3,4

With reference to table 4, when the access point receives and decodes the RRI codeword with the value '0', the access point attempts to decode the packet at a rate of 76.8 kbps. If the decoding of the sub-packet failed, the access point receives the next packet and decodes the RRI codeword with the value '1', the access point can combine the current sub-packet with the previously received sub-packet, since the RRI codeword with the value '1' identifies the current the resulting sub-packet with index '2', which can be combined with the sub-packet with index '1'.

As discussed above, the control channel is a reference signal, that is, the parameters of the control signal, such as structure, transmit power, and other parameters are known to the access point. Before receiving the control channel, the access point determines the parameters of the reverse control signal, after the influence of the communication channel. By comparing two sets of parameters, for example, parameters before transmission and received parameters, the access point can evaluate the communication channel and coherently demodulate the communication channels. Methods of using a reference signal to estimate a communication channel are known in the art. For example, in co-pending application for US patent No. 09 / 943,277, entitled, “METHOD AND APPARATUS FOR MULTI-PATH ELIMINATION IN A WIRELESS COMMUNICATION SYSTEM, dated August 30, 2001, owned by the present applicant.

With reference to FIGS. 4a-b, a reverse control channel used for estimating a reverse communication channel and coherent demodulation of channels transmitted in a first time half-interval is not available in a second time half-interval. However, the relatively high transmission power and sophisticated coding ensure that the probability of receiving and correctly decoding the channel RRI is high. Moreover, both the access terminal and the access point are provided with additional information presented in table 4.

Thus, the access point can hypothesize at what data rate and at what RRI the code word was transmitted, and try to decode the RRI by testing the hypothesis. Access selects the hypothesis that is most likely according to the metric used to test the hypothesis. As discussed below, the reverse control channel is transmitted with the power determined by the power control cycles so that the reverse control channel from all access terminals is received by the access point with the same power (P _Pilot ). Due to the fact that the RRI channel power (P _t ) is related to the transmit power on the reverse communication channel (see equation (3) below), once the RRI channel is correctly decoded, the access point can use equation (3) to determine the parameters of the RRI channel required to assess the quality of the reverse link. Accordingly, the RRI channel can be used as a reference signal instead of a control channel for evaluating the quality of the reverse communication channel and coherent demodulation of the channels transmitted in the second time interval.

For the correct use of equation (3), the access point must know the value A, the differential of the excess over the thermal (ROT) between the service intervals and the transmission intervals of the traffic. The access point measures the value of A, as described in more detail below.

Although the CDM traffic channel / CDM RRI channel has been described as using the same structure generating the TDM traffic channel and TDM RRI channel, it is not necessary, there may be separate structures for the CDM traffic channel, CDM RRI channel and TDM traffic channel and TDM RRI channel .

Reverse OFDM traffic channel

As already discussed, the transmission of the data rate depends on the characteristics of the communication channel, for example, the signal-to-interference and noise ratio (SINR); higher data rates require a higher SINR. Due to the fact that multipath interference makes a significant contribution to interference and noise, the suppression of interference at high data rates should significantly improve the performance of the communication system.

One means for suppressing multipath interference is orthogonal frequency division multiplexing (OFDM). OFDM is a known modulation method, the fundamentals of which are explained with reference to FIG. 6. The OFDM communication system 600 receives user data 602 and provides it to block 604. (Pre-processing of user data before block 604, for example, encoding, repetition, multiplexing, and the like, is not shown for brevity.) Block 604 distributes the user data to a plurality of parallel elements 606, the exact number of which is a function of the dimension of the used fast Fourier transform (FFT). Parallel elements 606 are modulated at block 608 by an inverse fast Fourier transform (IFFT). This modulated signal, containing a group of signals whose number is equal to the number of parallel elements, is then converted with increasing frequency into a set of auxiliary carriers 610 having a radio frequency, amplified and transmitted via communication channel 612. The signal is received and demodulated by block 614 using fast Fourier transforms. The demodulated data 616 is then redistributed by block 618 into user data 620.

User data is protected against multipath attenuation at a dedicated frequency. If the auxiliary carrier experiences attenuation, user data will only lose a small fraction of the total user data. Because the transmitted user data contains error correction bits, the missing fragments can be restored later.

The OFDM described above can be used for transmission in the second half of the TDM interval as follows. When the access terminal determines that the transmission rate of user data to be transmitted on the reverse link is above a predetermined threshold, for example, above 614.4 kbps, the access terminal transmits user data using OFDM instead of TDM.

Reverse OFDM speed indication channel

To provide the desired indication, OFDM RRI may contain 5 bits of information. An RRI value of 602 (2) is provided independently of user data 602 (1) to block 604 (in FIG. 6A), which distributes RRI data to at least one predetermined parallel element 602 (2), and which distributes user data to the remaining parallel elements 606 (1). (Pre-processing of RRI data before block 604, for example, encoding, repetition, multiplexing, and the like, is not shown for brevity.) Next, processing proceeds as shown in FIG. 6. Referring again to FIG. 6a, upon reception, a signal is received and demodulated at block 614 using FFT. The demodulated RRI data 616 (2) and the demodulated user data 616 (2) are then redistributed by block 618 to provide user 620 (1) and RRI values 620 (6).

Alternatively, user data and RRI data are multiplexed and provided to block 604 (in FIG. 6). (Pre-processing of the RRI data before block 604, for example, encoding, repetition, compression, and the like, is not shown for brevity.) Then, the RRI values and user data are distributed among the parallel elements 606. Next, the processing proceeds as shown in FIG. 6. Referring to FIG. 6c, after reception, the signal is received and demodulated at block 614 using FFT. The demodulated RRI data and demodulated user data 616 are then redistributed by block 618 to provide user 620 (1) and RRI values 620 (6).

Reverse Link Architecture

5 further illustrates a reverse link architecture. The TDM traffic channel 422 (T) and the TDM RRI channel 422 (RRI) (in FIG. 4) are time division multiplexed in block 514, and provided to the gain setting block 516 (1). After adjusting the gain, the time division multiplexed signal is provided to the modulator 518.

The control channel 412, the data request channel 414, the notification channel 416, the packet request channel 418 (in FIG. 4) are provided to respective gain tuning units 516 (2) -516 (5). After gain adjustment, the corresponding signals are provided to modulator 518.

Additionally, the optional CDM traffic channel / CDM RRI channel 420 (in FIG. 4) is provided to gain tuning units 516 (7). After adjusting the gain, the corresponding signals are provided to the modulator 518.

A modulator 518 combines the input channel signals and modulates the combined channel signals in accordance with a suitable modulation method, for example, binary phase shift keying (BPSK), quadratic phase shift keying (QPSK), quadrature amplitude modulation (QAM), 8-phase modulation (8-PSK) or other modulation methods known to the person skilled in the art. A suitable modulation method may vary in accordance with the speed of the data to be transmitted, the state of the channel and / or other design parameters of the communication system. The combination of incoming channel signals will change accordingly. For example, when the selected modulation method is QPSK, the input channel signals will be combined into phase and quadrature signals, and these signals will be quadrature expanded. The choice of channel signals is combined into phase and quadrature signals in accordance with the design parameters of the communication system, for example, the distribution of channels, so that data loading between phase and quadrature signals is balanced, the ratio of peaks to average for the resulting waveform is reduced, and other design parameters.

The modulated signal is filtered by block 520, upconverted to the carrier frequency in block 522, and provided for transmission.

Reverse Link Access Method

As already discussed, the transmission of user data on the reverse link from traditional access terminals uses code division multiplexing, for example, CDMA in accordance with the IS-856 standard. In accordance with the IS-856 standard, the access terminal can access the carrier frequency of the reverse communication channel, thereby autonomously initiating transmission on the reverse communication channel, without considering any potential distribution of the reverse communication channel between TDMA and CDMA intervals. The initial transmission on the reverse link occurs at a predetermined data rate, for example 9.6 kbps. When the reverse activity bit (RAB) received on the reverse activity channel is zero, the access terminal may increase the data rate to the next higher rate with probability p; when RAB is one, the access terminal may reduce the rate to the next lower rate with probability q. The probabilities p and q for each speed are either transmitted from the access network to the access terminals or are established between the access point and the access terminal, for example, during a connection.

Accordingly, new access terminals using code division multiplexing, such as CDMA in accordance with IS-856, can autonomously initiate transmission on the reverse link without considering any potential reverse link allocation between TDMA and CDMA intervals, as described above.

New access terminals using CDMA modulation in the assigned intervals can autonomously initiate transmission in the assigned for CDMA intervals, as described above.

Reverse channel transmissions from new access terminals using the intervals allocated for TDMA originate from at least one access terminal in a portion of the reverse channel interval. To illustrate how the structure of a single time slot interval described above can be extended to use a multiple time slot, data transmission on the reverse link, as described below, uses a slot equal to two time slots. However, as mentioned above, any number of time intervals can be used to form an interval. Access to the reverse channel carrier frequency for new access terminals using TDMA dedicated slots depends on the data multiplexing mode.

Those of the new access terminals that use only CDMA mode, that is, transmit user data using only CDMA in TDMA intervals, can access the carrier frequency of the reverse communication channel, thus, can autonomously initiate transmission on the reverse communication channel, as described above.

On the contrary, access to the carrier frequency of the reverse communication channel, therefore, for transmissions on the reverse communication channel by new access terminals using TDM / OFDM or CDM and TDM / OFDM mode, that is, transmitting user data using TDM / OFDM or CDM and TDM / OFDM in TDM intervals, is planned by an element in the access network in response to a request from the access terminal to transmit user data. Access terminals are scheduled according to the quality metric for the access terminal channel in the interval of the reverse communication channel, the average quality metric for the reverse communication channel of the access terminal, and the impatience function. If a new access terminal is not planned, that is, the access terminal is denied permission to transmit; the access terminal must stop transmitting at least in the TDM / OFDM portion of the interval. Thus, the access terminal either does not transmit data in the interval, or transmits data only in the CDM part of the interval, that is, using the CDM part of the TDMA interval.

One example reverse link data transmission for an access terminal requesting TDMA will be shown and explained with reference to FIG. 7. Fig.7 illustrates the coordination of data transmission on the reverse link for one access terminal, one access terminal is considered only for ease of understanding. Moreover, only one access point is shown. However, it should be understood that, as described above, the concept can be extended to multiple access terminals. In addition, many access points in the access network can receive and decode the reverse link from the transmitting access terminal and provide information about whether or not user data serving the access point has been successfully decoded. Alternatively, access points that receive useful information send useful information to the centralized element to perform soft decision decoding. Then, the central decoder notifies the serving access point whether the decoding of the useful information was successful. The serving access point shows the ACK on the PG channel, thereby preventing unnecessary retransmission.

Due to the fact that the access procedure, the selection of the serving sector and other call setup procedures are based on functions similar to the functions of the communication system according to the IS-856 standard, as described above, this description is not repeated. The only difference is that the new access terminals do not transmit the access channel probe during the TDM / OFDM time half-interval.

An access terminal (not shown) having received data to be transmitted and desiring to transmit in the TDMA interval, evaluates the reverse link channel quality metric of the access terminal and the impatience function for the TDMA interval, and generates a timeliness level (OL 1). For ease of understanding, it is assumed that all slots are for TDMA. The access terminal estimates the data rate at which it can transmit and generates the corresponding data types. As already discussed, the packet data types not only show the data rate, but also designate the packet as original or retransmitted. As will be described in more detail below, the rate determination method determines the maximum supported rate in accordance with the amount of data to be transmitted, the maximum transmit power of the access terminal and the transmit power allocated to the control channel. The access terminal then determines whether the rules for transmitting the next value on the packet ready channel are satisfied. Rules may include:

- the next value in the packet ready channel is transmitted during the interval, for example, two time intervals;

- the next value in the packet readiness channel is transmitted when the timeliness level changes;

- the next value in the packet readiness channel is transmitted even if the timeliness level has not changed, if the packet permission has not been received for a predetermined time interval;

- the packet ready channel is not transmitted if the access terminal does not have data to transmit.

When the rules are satisfied, the access terminal transmits the requested data rate and the timeliness level on the PR channel during time intervals n and n + 1.

A serving access point (not shown) of the access network receives a reverse channel and decodes the information contained in time intervals n and n + 1 in the interval N + 1. The serving access point then provides a level of timeliness, packet data type, and the requested data rate from all access terminals requesting permission to transmit data to a scheduler (not shown). The scheduler schedules packages for transfers in accordance with the planning rules. As already discussed, the planning rules try to minimize mutual interference in the reverse communication channel among the access terminals, while achieving the required QoS or equality in the distribution of data. The rules are formulated as follows:

i. the transmission advantage is granted to the access terminal reporting the highest level of timeliness;

ii. in the case where several access terminals have reported the same level of timeliness, an advantage in transmission is provided to the access terminal with lower transmitted bandwidth;

iii. in the case where several access terminals satisfy the rules (i) and (ii), the access terminal is randomly selected; and

iv. permission to transmit to one of the access terminals with data available for transmission, even if the reported level of timeliness is low, in order to maximize the use of the reverse link.

After the scheduling decision is made, the serving access station transmits the scheduling decision for each of the access terminals requesting permission to transmit over the PG channel. As shown in the drawing, the serving access point sends a scheduling decision (SD 0), rejecting the permission of the access terminal to transmit a new packet in intervals N + 2 and N + 3.

Due to the fact that the access terminal did not receive any response on the PG channel, and the access terminal has data to be transmitted, the access terminal again evaluates the quality metric of the reverse channel of the access terminal of the access terminal and the impatience function, which at this time leads to an increase in the level timeliness (OL 3). Then, the access terminal generates a packet data type and estimates the data rate, and provides the packet data type and the requested data rate on the RRI channel, and the timeliness level on the reverse link PR channel in time intervals n + 2 and n + 3.

The serving access point receives the return channel and decodes the information contained in time intervals n + 2 and n + 3 in the interval N + 3. The serving access point then provides the level of timeliness, packet data type, and the requested data rate from all access terminals requesting permission to transmit data to the scheduler. After the scheduling decision is made, the serving access station transmits the scheduling decision for each of the access terminals requesting permission to transmit over the PG channel. As shown in the drawing, the serving access point sends a scheduling decision (SD 1), allowing the transmission of a new packet in the intervals N + 4 and N + 5.

The access terminal receives the PG channel and decodes the scheduling decision (SD 0) transmitted in time intervals N + 2 and N + 3 in time interval n + 3. Thus, the access terminal refuses to transmit during time intervals n + 4 and n + 5. The access terminal has data that must be transmitted, respectively, the access terminal evaluates the quality metric of the reverse channel of the access terminal of the access terminal and the impatience function. As shown in the drawing, the access terminal determines the timeliness level (OL 3), which is the same as the two time slots back from this transmission, respectively, the access terminal refuses to transmit the PR channel during time intervals n + 4 and n + 5 .

The serving access point makes a scheduling decision (SD 1) to allow transmission to the access terminal, respectively, the serving access point transmits a scheduling decision to each of the access terminals requesting permission to transmit over the PG channel. As shown in the drawing, the serving access point sends a scheduling decision (SD 1), allowing the transmission of a new packet in the intervals N + 4 and N + 5.

The access terminal receives the PG channel and decodes the scheduling decision (SD 1) transmitted in time intervals N + 4 and N + 5 in time interval n + 5. In addition to the data transmitted in time intervals n + 6 and n + 7, the access terminal has data to be transmitted, respectively, the access terminal evaluates the quality metric of the reverse channel of the access terminal of the access terminal and the impatience function. As shown in the drawing, the access terminal determines the timeliness level (OL 2), respectively, the access terminal transmits a PR channel in time intervals n + 6 and n + 7. Because the access terminal is allowed to transmit, the access terminal further transmits user data in the TDM / OFDM portion of the reverse traffic channel in time intervals n + 6 and n + 7.

As shown in FIG. 7, the access terminal receives transmission permission after two requests. Each of the packet requests can be associated with the same package or with a different package. If each of the packet requests is associated with different packets, in one implementation, the access terminal autonomously decides which packet to send. Alternatively, the transfer permission is associated with the first unsatisfied packet request. However, other strategies fall entirely within the scope of the invention.

The serving access point receives the return channel and decodes the PR channel information contained in the time intervals n + 6 and n + 7 in the time interval N + 7, and user data contained in the time intervals n + 6 and n + 7 in the time intervals N + 8 and N + 9. The serving access point then provides the level of timeliness, packet data type, and the requested data rate from all access terminals requesting permission to transmit data to the scheduler. After the scheduling decision is made, the serving access station transmits the scheduling decision for each of the access terminals requesting permission to transmit over the PG channel. Since the access point has successfully decoded user data, the serving access point transmits a scheduling decision (SD 1) allowing transmission of a new packet at intervals N + 10 and N + 11.

The access terminal does not send PR neither in time intervals n + 8 and n + 9, nor in time intervals n + 10 and n + 11, because when the terminal evaluates the quality metrics of the reverse communication channel of the access terminal and the impatience function, the rules for transmitting the following values in the packet ready channel are not satisfied.

The access terminal receives the PG channel and decodes the scheduling decision SD 1 in the time interval n + 11. Because the access terminal is allowed to transmit, the access terminal further transmits user data in TDM / OFDM portions of the timely time slots n + 12 and n + 13.

The serving access point receives the reverse link and decodes user data contained in time intervals n + 12 and n + 13 into time intervals N + 14 and N + 15. Because the access point has successfully decoded user data, but the serving access point does not have a pending packet request, the access point does not betray the PG.

The case when the access point could not correctly decode the useful information sent on the reverse communication channel at time intervals n + 6 and n + 7 is shown in Fig. 8.

The serving access point receives the return channel and decodes the PR channel information contained in time intervals n + 6 and n + 7 in time interval N + 7, and user data contained in time intervals n + 6 and n + 7 in time intervals N + 8 and N + 9. The serving access point then provides the level of timeliness, packet data type, and the requested data rate from all access terminals requesting permission to transmit data to the scheduler. After the scheduling decision is made, the serving access station transmits the scheduling decision for each of the access terminals requesting permission to transmit over the PG channel. Since the access point was not able to successfully decode user data, the serving access point transmits a scheduling decision (SD -1), allowing the retransmission of a previously transmitted packet in time intervals N + 10 and N + 11.

The access terminal does not send PR neither in time intervals n + 8 and n + 9, nor in time intervals n + 10 and n + 11 because when the terminal evaluates the quality metrics of the reverse communication channel of the access terminal and the impatience function, the rules for transmitting the following value in the packet readiness channel are not satisfied. However, the access terminal sends PR at time intervals n + 10 and n + 11 because when the terminal evaluates the quality metrics of the reverse channel of the access terminal and the impatience function, the level of impatience has changed.

The access terminal receives the PG channel and decodes the SD -1 scheduling decision sent in time intervals N + 10 and N + 11 in time interval n + 11. Due to the fact that the access terminal is allowed to retransmit the previously transmitted packet, and not a new packet, the access terminal has data that must be transmitted, respectively, the access terminal evaluates the quality metric of the reverse channel of the access terminal of the access terminal and the impatience function. As shown in the drawing, the access terminal determines the timeliness level (OL 3), respectively, the access terminal transmits a PR channel in time intervals n + 12 and n + 13. Moreover, the access terminal retransmits user data in TDM / OFDM portions of the timely time slots n + 12 and n + 13.

The serving access point receives the reverse channel and decodes the PR channel information contained in time intervals n + 12 and n + 13 in time interval N + 13, and user data contained in time intervals n + 12 and n + 13 in time intervals N + 14 and N + 15. The serving access point then provides the level of timeliness, packet data type, and the requested data rate from all access terminals requesting permission to transmit data to the scheduler. After the scheduling decision is made, the serving access station transmits the scheduling decision for each of the access terminals requesting permission to transmit over the PG channel. Since the access point has successfully decoded user data, the serving access point transmits a scheduling decision (SD 1) allowing transmission of a new packet at intervals N + 14 and N + 15.

The access terminal receives the PG channel and decodes the scheduling decision SD 1 in the time interval n + 15. Due to the fact that the access terminal is allowed to transmit, the access terminal additionally transmits user data in TDM / OFDM parts of the timely time slots n + 16 and n + 17.

The serving access point receives the reverse link and decodes user data contained in time intervals n + 16 and n + 18 in time intervals N + 18 and N + 19. Because the access point has successfully decoded user data, but the serving access point does not have a pending packet request, the access point does not betray the PG.

It should be understood that the serving access point may schedule the access terminal in accordance with its most recent received transmission request.

It should be understood that the serving access point may not be able to receive the PR channel. Since the access terminal does not transmit the PR channel until the timeliness level has changed, in order to prevent a failure in the communication session, the access terminal retransmits the PR channel after a predetermined amount of time.

It should be understood that a packet access network may not be able to receive a packet even after several retransmission attempts. To prevent excessive retransmission attempts, the communication system may refuse retransmission attempts after a certain number of retransmission attempts (retention interval). Then, the missed packets are processed in another way, for example, the radio communication protocol (RLP).

Reverse Link Power Control

As already discussed, at least one access terminal in the sector transmits a data stream over the reverse link using TDMA. Due to the fact that in a CDMA communication system all terminals transmit at the same frequency, each transmitting terminal acts as an interference source for access terminals in neighboring sectors. To minimize such interference in the reverse link and maximize capacity, the transmit power for the control channel of each access terminal is controlled by two power control cycles. Then, the transmit power of the remaining overhead channels and CDMA traffic channels is determined as a fraction of the transmit power on the control channel. The transmit power on the TDM traffic channel is defined as the ratio of the traffic-to-control signal power for a given data rate, adjusted using the differential over the thermal (ROT), between service intervals and traffic transmission intervals. The excess over thermal is the difference between the noise level of the receiver and the total received power, as determined by the access terminal.

Control channel power control

The control channel power control loops are similar to the loops in a CDMA system disclosed in US Pat. No. 5,056,109 entitled “METHOD AND APPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULAR MOBILE TELEPHONE SYSTEM”, issued to the applicant of the present invention and incorporated herein by reference. Other power control methods are also contemplated and are within the scope of the present invention.

The first power control cycle (external cycle) adjusts the control point so that the desired level of performance is maintained, as estimated in the sector receiving the reverse communication channel with the best quality metric. The performance level includes, for example, the erasure rate of the DRC channel and the frequency of occurrence of erroneous packets (PER) in the CDM traffic channel. The checkpoint is updated in accordance with the following rules:

the control point decreases if the DRC channel erasure rate is less than a threshold value, for example, 25%, and the CDM packet was successfully decoded, provided that the CDM-RRI was successfully detected;

the control point increases if the erasure rate of the DRC channel is greater than the threshold value, and the CDM packet was not successfully decoded, provided that the CDM-RRI was successfully detected;

the control point is updated periodically, through each predetermined number of frames, the update is followed by the choice of diversity by the access point. The erasure rate of the DRC channel is measured over this interval. If no CDM traffic channel was received during the update interval, then the control point is updated only in accordance with the erasure rate of the DRC channel. If the predetermined number of frames is more than one frame, then the checkpoint is updated either after the update interval has expired or if it is not possible to successfully decode the CDM packet, provided that the CDM-RRI has been successfully detected.

The second power control cycle (internal cycle) adjusts the transmit power of the access terminal so that the quality metric of the reverse link is maintained at the control point. The quality metric includes the ratio of energy per micro frame to noise plus interference (Ecp / Nt), and is measured by the access point receiving the return channel. Accordingly, the control point is also measured in Ecp / Nt. The access point compares the measured Ecp / Nt with the power control set point. If the measured Ecp / Nt is greater than the reference point, then the access point transmits power control messages to the access terminal to reduce the transmit power of the access terminal. Conversely, if the measured Ecp / Nt is less than the reference point, then the access point transmits power control messages to the access terminal to increase the transmit power of the access terminal. The power control message is implemented as one power control bit. The first value of the power control bit (“up”) instructs the access terminal to increase the transmit power of the access terminal, and the second value of the power control bit (“down”) instructs the access terminal to reduce the transmit power of the access terminal. An access terminal receiving power control bits from multiple sectors reduces transmission power if one of the power control commands is “down” and increases in all other cases.

Power control bits for all access terminals associated with the access point are transmitted over MAC channels in the forward link.

Power management of the remaining service channels and CDM traffic channel

After the transmission power for the control channel is determined in the time interval, as a result of the power control cycles, the transmission power for the remaining service channels and the CDM traffic channel is determined as the ratio of the transmission power of a certain service channel and the CDM channel to the transmission power of the control channel. The relationships for each service channel and CDM channel are determined in accordance with modeling, laboratory experiments, field trials and other engineering methods known to a person skilled in the art.

Thus, for example, the power of the CDM traffic channel / RRI channel, referred to the power of the control channel of the reverse traffic channel, depends on the data transfer speeds, as shown in table 5.

Table 5 Data rate (kbps) Data Channel Gain to Control (dB) 0 -∞ (no data channel is transmitted) 9.6 DataOffsetNom + DataOffset9k6 + 3.75 19.2 DataOffsetNom + DataOffset19k2 + 6.75 38.4 DataOffsetNom + DataOffset38k4 + 9.75 76.8 DataOffsetNom + DataOffset76k8 + 13.25 153.6 DataOffsetNom + DataOffset153k6 + 18.5

TDM traffic channel power control

The required transmit power of the traffic channel is also determined in accordance with the transmit power of the control channel. In one implementation, the required traffic channel power is calculated using the following formula:

(3)

(3)

where P _t is the transmit power of the traffic channel;

P _pilot - transmit power of the control channel;

G ( r ) is the ratio of the transmit power of the traffic to the control channel for a given speed r ; and

A - estimated differential thermal excess (ROT), between service intervals and traffic transmission intervals. The term excess over thermal is the difference between the noise level of the receiver and the total received power, as defined by the access terminal.

The measurement of the ROT in the transmission interval of the overhead transmission (ROToverhead) and in the transmission interval of the traffic (ROTtraffic) necessary for calculating A by the access point is well known in the art. Such a measurement is described in the disclosure of US patent No. 6,192,249, entitled "Method and apparatus for reverse link loading estimation", issued to the applicant of the present invention. After the noise level is measured for both service intervals and traffic intervals, A is calculated using the following formula:

(4)

(four)

The calculated value A is then transmitted to the access point, for example, on a traditional RA channel, if only access terminals using TDMA are available in the communication system, or on a new RA channel, if traditional and new access terminals are operating in the communication system.

Alternatively, the value A represents the estimate of the differential ROT given by equation (3). The initial value of A is determined in accordance with modeling, laboratory experiments, field tests and other engineering methods known to a person skilled in the art. Then the value A is adjusted in accordance with the frequency of occurrence of erroneous packets (PER) in the reverse communication channel so that a specific PER is supported for the maximum allowed number of transmissions of this packet. The frequency of occurrence of erroneous packets in the reverse communication channel is determined in accordance with the ACK / NACK packets of the reverse communication channel, as described above. In one implementation, the value of A is increased by a first predetermined amount if the ACK was obtained within N retransmission attempts from the maximum number M of retransmission attempts. Similarly, the value of A decreases by a second predetermined amount if the ACK was not obtained within N retransmission attempts from the maximum number M of retransmission attempts.

From equation (3) it follows that the transmission power of the traffic channel is a function of the data rate r . In addition, the access terminal is limited in maximum transmit power ( P _max ). Thus, the access terminal first determines how much power is available from P _max and a specific P _pilot . The access terminal then determines the amount of data to be transmitted, and selects a data rate r in accordance with the available power and amount of data. The access terminal then solves equation (3) to determine if the effect of the estimated noise differential A leads to exceeding the maximum available power. If the maximum available transmit power is exceeded, then the access terminal reduces the data rate r and repeats the process.

The access point can control the maximum data rate at which the access terminal can transmit by providing the access terminal with the maximum allowed value of G ( r ) A via the traditional RA channel, if only the access terminals operating in TDMA are presented in a communication system, or RA channel, if traditional and new access terminals operate in a communication system.

Alternatively, the access terminal determines the value of G ( r ) A in accordance with the ratio of the traffic power to the control channel and the estimate A is adjusted in accordance with the frequency of occurrence of erroneous packets (PER) in the reverse communication channel determined in accordance with ACK / NACK, as was described above.

Packet Decoding Modification

The above ratio of the transmit power of the traffic to the control channel G ( r ) for a given speed r is determined by taking into account the number of retransmissions (transmissions) of the packet for correct decoding. Thus, if the packet must be correctly decoded in one transmission, then the ratio of the transmit power of the traffic to the control channel is greater than the ratio of the transmit power of the traffic to the control channel if one or more transmissions are allowed.

The number of transmissions (retransmissions) determines the latency, which affects the quality and class of the provided data services (QoS). Due to the fact that different types of packets, such as voice packets, file transfer protocol packets, and the like, require different QoS, different ratios of traffic transmission power to the control channel may be assigned to different packet types. Thus, for example, when the access terminal determines that a voice packet requiring a certain QoS (low latency) must be transmitted, the access terminal uses the first ratio of the transmit power of the traffic to the control channel, which is greater than the second ratio of the transmit power of the traffic to the control channel used when an FTP packet requiring a different QoS (high latency) is to be transmitted.

Channel RRI Power Control

As described above, the RRI channel is time division multiplexed with the payload channel. In order to avoid transmitting the RRI of the part into the time interval of the traffic channel / RRI at a power level different from the power level of the part of the traffic, the power distribution between the RRI channel and the traffic channel is controlled by the number of micro frames allocated to the RRI channel as a function of the data rate.

In order to guarantee the correct decoding of a certain number of micro frames containing Walsh encoded codewords, the required power can be determined. Alternatively, if the power for the traffic / payload to be transmitted is known, and the RRI part of the traffic channel / RRI is transmitted with the same power, then the number of microframes adequate for reliable decoding of the RRI channel can be determined. Accordingly, as soon as the data rate is determined, and accordingly, the power for transmitting the time interval of the traffic channel / RRI is determined, this is the number of micro frames allocated to the RRI channel. The access terminal generates a five-bit packet type, biorthogonally encodes five bits to receive characters, and fills the number of frames allocated to the RRI channel with characters. If the number of micro frames allocated to the RRI channel is greater than the number of characters, the characters are repeated until all the micro frames allocated to the RRI channel are full.

AT and AP structures

Access terminal 900 is shown in FIG. 9. Forward channel signals are received by antenna 902 and sent to preprocessor 904, comprising a receiver. The receiver filters, amplifies, demodulates and digitizes the signal provided by the antenna 902. The digitized signal is provided to the demodulator (DEMOD) 906, which provides demodulated data to the decoder 908. The decoder 908 performs the functions inverse to the signal processing functions applied by the access terminal and provides decoded user data to the receiver 910 data. Then the decoder communicates with the controller 912, providing the controller 912 service data. Then, the controller 912 communicates with the other blocks forming the access terminal 900 to provide appropriate control of the operation of the access terminal 900, for example, data encoding, power control. The controller 912 may comprise, for example, a processor and a storage medium associated with the processor and comprising a set of instructions executed by the processor.

The user data to be transmitted to the access terminal is provided by the data source 914 according to the instructions of the controller 912 to the encoder 916. The encoder 916 is then provided with the service data by the controller 912. The encoder 916 encodes the data and provides the encoded data to the modulator (MOD) 918. Data processing in the encoder 916 and modulator 918 is performed in accordance with the generation of the reverse communication channel, as described above in the text and shown in the drawings. The processed data is then provided to the transmitter within the preprocessor 904. The transmitter modulates, filters, amplifies and transmits the signal of the reverse communication channel through the air, through the antenna 902, via the reverse communication channel.

The controller 1000 and access terminal 1002 are shown in FIG. 10. The user data generated by the data source 1004 is provided through an interface unit, for example, through a packet network interface (PSTN) (not shown), to a controller 1000. As described, the controller 1000 communicates with a plurality of access terminals to form an access network. (Only one access terminal 1002 is shown in FIG. 10 for simplicity). User data is provided to a plurality of selector elements (only one selector element 1002 is shown in FIG. 10 for simplicity). One selector element is assigned to control the exchange of user data between the data source 1004 and the data receiver 1006 and one or more base stations under the control of the call control processor 1010. The call control processor 1010 may comprise, for example, a processor and a storage medium associated with the processor and comprising a set of processor-executable instructions. As shown in FIG. 10, the selector element 1002 provides user data to a data queue 1014 that contains user data to be transmitted to access terminals (not shown) served by the access terminal 1002. In accordance with the control of the scheduler 1016, user data is provided by the data queue 1014 to the channel element 1012. Channel element 1012 processes user data in accordance with IS-856, and provides processed data to transmitter 1018. Data is transmitted on the forward link through an antenna 1022. Reverse channel signals from access terminals (not shown) are received by antenna 1024 and provided to receiver 1016. A receiver 1016 filters, amplifies, demodulates, and digitizes a signal provided by an antenna 1024 and provides a digitized signal to a channel element 1016. Channel element 1016 performs the inverse functions of the signal processing functions applied by the access point and provides decoded user data to selector element 1012. A selector 1012 sends user data to a data receiver 906, and overhead data to a call control processor 1010.

One of skill in the art should understand that although flowcharts depict sequential operations for simplicity, some steps can be performed in parallel in a real implementation.

One of skill in the art should understand that information and signals may be represented using any of a variety of technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and micro frames that appear in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

One skilled in the art will appreciate that any illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate this interchangeability of hardware and software, various components, blocks, modules, circuits, and steps have been described, in general, in terms of their functionality. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the entire system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as falling outside the scope of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the implementations disclosed herein may be implemented or implemented using a general purpose processor, digital signal processor (DSP), custom integrated circuit (ASIC), field programmable gate array (FPGA), or another programmable logic device, a discrete gate circuit or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described here th. A general purpose processor may be a microprocessor, but, in the alternative, the processor may be a conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a DSP and a microprocessor, a plurality of microprocessors, one or more processors associated with a DSP core, or any other similar combination.

The steps of a method or algorithm described in connection with the implementations disclosed herein may be implemented directly in hardware, in a software module executed by a processor, or a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or another type of storage medium known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. ASIC may reside in a user terminal. Alternatively, the processor and the storage medium may reside in the discrete components of a user terminal.

The above description of the disclosed implementations is provided so that one skilled in the art can make and use the present invention. Various modifications to these implementations will be apparent to those skilled in the art, and the basic principles defined herein can be applied to other implementations without departing from the scope of the invention. Thus, the present invention is not intended to limit the implementations presented here, but rather corresponds to the broadest scope consistent with the principles and distinguishing features disclosed herein.

Part of the disclosure of the present invention contains materials that are protected by copyright. The copyright owner has no objection to anyone accurately reproducing the patent document or disclosing it as it is in the archive of the Patent Office, but in all other cases reprinting is prohibited.

Claims (34)

1. A device for controlling channel power, comprising
means for determining the transmit power of the first channel;
means for determining the quality and class of the provided data transmission services (QoS) provided by the channel;
means for determining the ratio of the transmit power of the channel to the first channel for the data rate at which the channel will be transmitted in accordance with QoS;
means for adjusting the transmission power ratio in accordance with the channel quality metric; and
means for calculating the transmission power of the channel in accordance with the adjusted transmission power ratio. 2. The device according to claim 1, wherein said means for determining the power of the first channel includes
means for determining a control point in accordance with the quality metric of the second channel and the detected presence of user data in the third channel; and
means for increasing the transmit power value if the current transmit power value is less than at a certain reference point. 3. The device according to claim 2, which also contains means for reducing the value of the transmit power if the current value of the transmit power is less than at a certain reference point. 4. The device according to claim 2, wherein said means for determining a control point in accordance with the quality metric of the second channel and the detected presence of user data in the third channel includes means for determining the quality metric of the second channel; means for detecting the presence of user data in the third channel; means for decoding user data if the presence of user data in the third channel has been detected, and determining a control point in accordance with the quality metric and the detection results. 5. The device according to claim 4, wherein said means for determining a quality metric of the first channel includes means for determining an erasure rate of the second channel. 6. The device according to claim 4, in which said means for detecting the presence of user data in the third channel includes
means for constructing a set of hypotheses in accordance with the speed of the control data and the content of the control data;
means for decoding control data in accordance with each set of hypotheses;
means for selecting the most likely hypothesis in accordance with the metric used to test the hypotheses; and
means for declaring the availability of user data if the selected hypothesis is greater than the first threshold value. 7. The device according to claim 4, wherein said means for decoding user data, if the presence of user data in the third channel has been detected, includes means for decoding user data, code division multiplexed (CDM), from the third channel. 8. The device according to claim 4, in which the specified means for determining a control point in accordance with the quality metric and the detection results includes
means for reducing the control point if the quality metric is less than the second threshold value and decoding was successful; and
means for increasing the control point if the quality metric is greater than the second threshold value and decoding was unsuccessful when the presence of user data was detected. 9. The device according to claim 4, in which the specified means for determining a control point in accordance with the quality metric and the detection results includes
means for reducing the control point if the quality metric is less than the second threshold value and decoding was successful; and
means for increasing the control point if the quality metric is greater than the second threshold value when the presence of user data has not been detected. 10. The device according to claim 2, wherein said means for adjusting the transmit power ratio in accordance with the channel quality metric includes means for increasing the transmit power ratio by a first determined amount when the first determined number of retransmissions of user data on the channel was unsuccessful. 11. The device according to claim 2, wherein said means for adjusting the transmit power ratio in accordance with the channel quality metric includes means for reducing the transmit power ratio by a second determined amount when user data has been successfully transmitted over the channel for a second determined number of retransmissions gears. 12. The device according to claim 2, wherein said means for adjusting the ratio of the transmission power in accordance with the channel quality metric includes
means for determining the differential of excess over thermal between the transmission interval of the first channel and the transmission interval of the channel;
means for adjusting the differential of excess over thermal;
means for adjusting the transmission power ratio in accordance with the adjusted differential of excess over thermal. 13. The device according to item 12, in which the specified means for determining the differential of excess over thermal between the transmission interval of the first channel and the transmission interval of the channel includes
means for measuring excess over thermal in the transmission interval of the first channel;
means for measuring excess over thermal in the transmission interval of the channel; means for calculating the difference between excess over thermal in the transmission interval of the first channel and excess over thermal in the transmission interval of the channel. 14. The device according to item 12, in which the specified means for determining the differential of excess over thermal between the transmission interval of the first channel and the transmission interval of the channel includes a means for estimating the differential of excess over thermal. 15. The device according to 14, in which the specified means for estimating the differential over the thermal includes a means for estimating the differential over the thermal in accordance with the channel quality metric. 16. The device according to claim 2, in which the channel is the first traffic channel, wherein the first channel is a control channel. 17. The device according to claim 3, in which the second channel is a data request channel, while the third channel is a second traffic channel. 18. The channel power control method, the method comprises the steps of:
determine the transmit power of the first channel;
determine the quality and class of data transmission services (QoS) provided by the channel;
determine the ratio of the transmit power of the channel to the transmit power of the first channel for the data rate at which the channel will be transmitted in accordance with QoS;
adjust the transmit power ratio in accordance with the channel quality metric;
calculate the transmit power of the channel in accordance with the adjusted ratio of the transmit power. 19. The method according to p, in which when determining the power of the first channel
determine the control point in accordance with the quality metric of the second channel and the detected presence of user data in the third channel and
increase the transmit power value if the current transmit power value is less than at a certain reference point. 20. The method according to claim 19, which also comprises reducing the transmit power value if the current transmit power value is less than at a certain reference point. 21. The method according to claim 19, in which when determining the control point in accordance with the quality metric of the second channel and the detected presence of user data in the third channel determines the quality metric of the second channel; detect the presence of user data in the third channel; user data is decoded if the presence of user data in the third channel has been detected, and a control point is determined in accordance with the quality metric and the detection results. 22. The method according to item 21, in which when determining the quality metric of the second channel determines the erasure rate of the second channel. 23. The method according to item 21, in which when detecting the presence of user data in the third channel, a set of hypotheses is built in accordance with the speed of the control data and the content of the control data; decode control data in accordance with each set of hypotheses; select the most probable hypothesis in accordance with the metric used to test the hypotheses, and declare the availability of user data if the selected hypothesis is greater than the first threshold value. 24. The method according to item 21, in which the processor decodes user data if the presence of user data in the third channel has been detected by executing a set of instructions for decoding user data, code division multiplexed (CDM), from the third channel. 25. The method according to item 21, in which when determining a control point in accordance with the quality metric and the detection results, reduce the control point if the quality metric is less than the second threshold value and decoding was successful, and increase the control point if the quality metric is greater than the second the threshold value and decoding was unsuccessful when the presence of user data was detected. 26. The method according to item 21, in which when determining a control point in accordance with the quality metric and the detection results, reduce the control point if the quality metric is less than the second threshold value and decoding was successful, and increase the control point if the quality metric is greater than the second threshold value when the presence of user data has not been detected. 27. The method according to p. 18, in which when adjusting the ratio of the transmission power in accordance with the channel quality metric, the transmission power ratio is increased by a first determined amount when the first determined number of retransmissions of user data on the channel was unsuccessful. 28. The method according to p. 18, in which when adjusting the ratio of the transmit power in accordance with the channel quality metric, the ratio of the transmit power is reduced by a second determined amount when the user data has been successfully transmitted over the channel for the second determined number of retransmissions. 29. The method according to p. 18, in which when adjusting the ratio of the transmission power in accordance with the channel quality metric, determine the differential over the thermal between the transmission interval of the first channel and the transmission interval of the channel; adjust the differential of excess over thermal; and adjust the ratio of the transmission power in accordance with the adjusted differential of excess over thermal. 30. The method according to clause 29, in which when determining the differential of excess over thermal between the transmission interval of the first channel and the transmission interval of the channel measure the excess over thermal in the transmission interval of the first channel; measure the excess over thermal in the transmission interval of the channel; and calculate the difference between the excess over thermal in the transmission interval of the first channel and the excess over thermal in the transmission interval of the channel. 31. The method according to clause 29, in which when determining the differential of excess over thermal between the transmission interval of the first channel and the transmission interval of the channel evaluate the differential of excess over thermal. 32. The method according to p. 31, in which when assessing the differential over the thermal estimate the differential over the thermal in accordance with the channel quality metric. 33. The method of claim 18, wherein the channel is a first traffic channel and the first channel is a control channel. 34. The method according to claim 19, in which the second channel is a data request channel and the third channel is a second traffic channel.

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