WO2002017665A1

WO2002017665A1 - Method of pre-configuring radio base station cells and channels in a telecommunication system

Info

Publication number: WO2002017665A1
Application number: PCT/SE2001/001767
Authority: WO
Inventors: Mikael ÖGREN; Andreas Ohlsson
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2000-08-21
Filing date: 2001-08-17
Publication date: 2002-02-28
Also published as: SE0002959L; AU2001280406A1; SE0002959D0

Abstract

The present invention relates to a method in a telecommunications system of configuring a radio base station (1) by means of parameter interchange between the radio base station (1), a central configuration management unit (10) and a radio network controller (8). According to the invention, standardised common parameters are interchanged when configuring cells and common control channels, both relating to the radio base station (1). Furthermore, the method is characterised by the steps of: setting up at least one local cell by means of the radio base station (1); transmitting a cell set-up response message and/or a common transport channel set-up response message from the radio base station (1) to the radio network controller (8); transmitting indications of resource operational state and/or availability status from the radio base station (1) to the radio network controller (8); and responding by transmitting, from the radio network controller (8) to the radio base station (1) and in dependence of the indications, additional information for making the local cell operational.

Description

Method of pre-configutϊng radio base station cells and channels in a telecommunication system

Technical field of the invention

The present invention generally relates to the technical field of cellular communication. More in detail, the invention concerns a method of pre-configuring radio base station cells and channels in a telecommunications system.

Background art

The amount of infrastructure for enabling wireless communication of different kinds has been increasing rapidly during the last two decades. Since the current telecommunications standard GSM had its break-through in the industrialised world, the number of subscribers has increased exponentially at very fast rates, and is expected to do so also in the so-called developing countries in a near future.

Not only the number of subscribers has risen, but also the amount of transferred information, irrespective of whether it is data or voice information. Today's possibil- ity of transferring greater amounts of data has influenced people's behaviour dramatically and the demand for higher transmission rates is by far greater than it used to be. The increased transmission needs invariably requires enhanced network communication capacity. Especially densely populated urban areas and road sections with heavy traffic need enhanced communication capacity, not the least during rush hours in the mornings and in the evenings.

It is evident that capacity problems occur in communication networks when the telecommunication traffic exceeds a certain upper limit set by the network. One solution to the problem of limited transmission capacity is to use modulation tech- niques that permit and support enhanced rates of data and voice traffic. Science and applied research in the field of telecommunication and data communication as well as signal processing has proposed and implemented a large number of effective measures, by which the capacity and data transmission rates have been increased significantly. Another supplementary way of increasing the network capacity is to add one or several additional transmitting and receiving base stations when and where the most urgent capacity need has been localised. However, adding another base station in a geographical area covered by already existing base stations is a delicate and complicated task, and consideration must be made to each of neighbouring base stations in order cause a minimum of radio frequency interference and disturbance.

Traditionally when an additional base station added to a communication network, the new base station is first put into position and then manually tuned. Technically qualified personnel is required to install the equipment, to initialise the functionality and tune signal-to-noise levels. Another assignment is to measure how the added base station disturbs and interferes with neighbouring base stations, and in what way the added base station is disturbed or influenced negatively by the signal levels of existing base stations. These tasks altogether make up a labour-intensive work, requiring a lot of qualified manpower and is comparatively quite costly for most manufacturers and operators of telecommunication systems.

The patent application WO 96/14720 describes a method configuration of a base station in order to centralise control and to simplify field installations of base stations.

Summary of the invention

One of the purposes of the present invention is to alleviate problems associated with prior art technology. Its is done by a method in a telecommunications system of configuring a radio base station by means of parameter interchange between the radio base station, a central configuration management unit and a radio network con- troller. Standardised common parameters are interchanged when configuring cells and common control channels, both relating to the radio base station. Furthermore, the method is characterised by the steps of: setting up at least one local cell by means of the radio base station; transmitting a cell set-up response message and/or a common transport channel set-up response message from the radio base station to the radio network controller ; transmitting indications of resource operational state and/or availability status from the radio base station to the radio network controller; and responding by transmitting, from the radio network controller to the radio base station and in dependence of the indications, additional information for making the local cell operational.

There are several advantages associated with this solution. When planning a cellular network for a telecommunications system it is advantageous be able to simulate the behaviour and performance of the system before implementing it physically. Favourable interaction as well as disturbances and interference with other radio base stations can be monitored and modelled at a early stages of the planning and development. In one situation, upgrading of an existing radio base station with new hardware components allowing higher data transmission rates may be sufficient, and in another situation the radio base station must be replaced by a new high performance radio base station provided with state of the art data transmission capacity to meet the network requirements. A third option is to add another radio base station, whereby the number of radio base stations in a certain geographical area is in- creased and thus also the network capacity. These options when planning a cellular network can be elaborated with and a careful analysis must be made, and utilisation of the method according to the present invention is advantageous when analysing the conditions. By using the method according to the present invention, conditions can be simulated in advance, whereby the procedure of installing and configuring a radio base station is made efficient and at the same time flexible and less costly for the operator. Another limiting factor associated with prior art, which is alleviated by means of the present invention is the sometimes delayed supply and accessibility of crucial hardware components required by the manufacturers of for example base stations for telecommunications systems. At numerous occasions, involved parties, i.e. manu- facturers of telecommunication systems and operators of telecommunication systems, have had to postpone production as well as upgrading and installation of base station equipment due to such delays in the supply of components. By means of the invention, cell planning and simulations can be performed when certain hardware means in the radio base station are still missing. That is another great benefit of the present invention.

Brief description of the drawings

The above and further features, advantages and benefits of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters and figures refer to like parts throughout, and in which:

Fig 1 shows a schematic overview of comprised units in a telecommunications sys- tern according to the invention.

Fig 2 is an overview of cell configuration units and their intermediate transmission lines.

Fig 3 is a flow chart with notifications, which are transferred between the configuration units in the form of information messages.

Fig 4 is a transmission scheme according to the present invention

Detailed description The following description is of the best mode presently contemplated for practising the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be ascertained with reference to the issued claims.

The present invention is applicable for use in a data and voice transmitting system using anyone of the contemporary multiple access methods, but especially in a cellular telecommunications system utilising the technology of code division multiple access (CDMA). CDMA is known to be a multiple access method based on the spread spectrum technique, which is used in addition to the prior known technologies FDMA (frequency division multiple access), TDMA (time division multiple access) and their different sub-systems.

One of the major benefits with CDMA in comparison with the above mentioned technologies is a significantly enhanced spectral efficiency, which enables considerably higher rates of data transmission. Another beneficial property is a simplified frequency planning, which is important for maintenance and installation of new radio base station units. The general approach in CDMA is to let different users transmit on the same frequency band simultaneously. A separate and individualised spreading code is used both by the transmitting and receiving units in order to distinguish between different data transmissions and voice conversations over each connection. The connection is normally between a base station, such as an RBS (radio base station), and a mobile terminal. In many cases, the mobile terminal is a mobile telephone, but several types of mobile communication units are conceivable to use, e.g. PDAs, PCs, and laptops, and therefore the term mobile terminal is used as a generic designation throughout this document for all possible stationary and mobile communication means.

With reference to Fig 1 is illustrated a cellular communications system including a plurality of radio base stations 1, which are spaced apart from each other. For illustration simplicity reasons, the radio base stations 1 are positioned equally distanced from each other throughout the geographical area. The radio base stations 1 can be described as radio transceivers which once they are configured, installed and operating, are maintained in fixed positions from where they transmit and receive radio frequency signals by which the cellular communications system is handled and its mobile terminals operate.

Each of the radio base stations 1 operate in a certain geographical area in which they can be reached bi-directionally. The geographical areas of sufficient radio frequency coverage are called cells 2, 3, 4 in the communication network. Cells 2, 3, 4 may be more or less overlapping and similar or even identical coverage areas of several cells 2, 3, 4 is quite possible. A mobile terminal 5, 11 is free to move from one cell to the other in the communication network, whereby the mobile terminal 5, 11 communicates with different radio base stations during its movement along a fortuitous path 6. So-called handover is used when the mobile terminal 5, 11 moves into a position where it is about to pass the border-line 7 from the radio frequency coverage of one cell to another at the same time as the responsibility for handling the communication is transferred from one radio base station to another. It is possible that handover is performed from one cell to another cell with an identical or similar coverage area.

A unit called the radio network controller (R C) 8 is conventionally coupled to a plurality of radio base stations 1. The radio network controller 8 manages and controls the configuration of a single one, or in most cases a plurality of radio base stations 1 as an example of one of several other responsibilities. Exactly how the con- figuration of radio base stations 1 is managed and controlled will be discussed in more detail below. A plurality of radio network controllers 8, 9 are supervised and controlled by a central configuration management unit 10, which unit 10 thus has the overarching responsibility for configuration in a wide geographical area and of a significant number of units in the described telecommunication system. Once the infrastructure of the cellular communication system is installed, configured and placed into service in the whole geographical area to be served, bidirectional communication is supported and permitted between any of the handled mobile terminals 5, 11. Those mobile terminals 5, 11 can be positioned at any loca- tion within the same geographical area, but also in other geographical areas encompassed by for instance another cellular communication network by means of roaming.

With reference to Fig 2 showing the configuration units more in detail, the radio network controller 8 is coupled to the central configuration management unit 10 and to one of the radio base stations 1. Even though Fig 10 does not outline any communication line between the radio network controller 8 and the central configuration management unit 10, such a communication line exist in some systems. In this case, the radio base station 1 is a recently installed unit, which has been added to the tele- communication network and has not yet been fully configured. Communication with the radio base station 1 is effected bi-directionally via an input/output 12 of the radio network controller 8, which is connected to an input/output 13 (sometimes called Iub) of the radio base station 1. The radio base station 1 is likewise connected to the central configuration management unit 10, also this in both directions, via an input/output 14 (sometimes called Mub).

Fig 3 shows a flow chart of how a configuration procedure can be performed. In particular, the interaction between the communication network units is stressed, with information message transmission between the radio base station 1, the radio network controller 8 and the central configuration management unit 10. Conceivably, the connections are traditionally by wire or cable, but any cordless interface with equal functionality, i.e. robustness, reliability and data transmission capacity, etc, would be a possibility. A variety of transport techniques may be used, such as ATM (asynchronous transfer mode) and various IPs (internet protocols). According to the present invention, configuration of the radio base station 1 proceeds in the following manner: initially a base station is configured, for instance by a radio base station operator using a personal computer or other kind of management tool. Hereby, logical cells are created, which logical cells are mapped to physical hardware resource sectors at the radio base station. Certain cell parameters including a local cell identifier (local cell ID), a corresponding base station sector identifier (sector ID), a cell radio frequency carrier number, and other necessary parameters are established by the radio base station 1. The radio base station 1 then communicates this cell sector configuration data to the radio network controller 8 in a status message, such as the resource status indication message (RSIM). In response to such a message, the radio network controller 8 virtually sets up the cell and establishes the appropriate and above mentioned cell parameters. After the radio network controller 8 has set up a cell, the radio base station 1 is able to send data messages reporting on for example resource availability, capability, errors, faults, etc, to the radio network controller 8.

When setting up a cell, the radio network controller 8 establishes a global cell identifier (global cell ID) and associates it with the local cell ID previously described and established by the radio base station 1. Furthermore, the radio network control- ler establishes a central frequency used for finding appropriate uplink- and downlink frequencies within the cell. After having set up the cell, the radio network controller 8 configures cell resources including various radio channels, e.g. common channels, traffic channels, etc, along with cell resource parameters. Once configuration is completed, the radio base station 1 sends status messages and/or reports to the radio network controller 8. One of the pieces of information in a status message/report of the above kind is the resource capability of the cell and errors occured, wherever applicable.

More generally described and with direct reference to Fig 3, a configuration proce- dure begins with an information message from the central configuration management unit 10, ordering (step 1) the radio base station 1 to establish a local cell. This information message reaches the radio base station 1 via its input/output 14 (Mub). As soon as a local cell is established, the radio base station 1 responds (step 2) to the radio network controller 8 with an information message indicating its resource status via the input/output 13 (Iub). This is an indication that informs the radio net- work controller 8 about the recently established and available cell. However, at this stage in the configuration procedure, the cell is not yet operational. Therefore, the radio network controller 8 sends a message to the radio base station 1 via the input/output 12 requesting (step 3) completion of the cell set-up. In order to do so, further information which is required is appended to the sent information message for enabling the recently established cell to become fully operational.

After having received the required additional information for enabling the cell to become fully operational, the radio base station 1 confirms (step 4) reception of the information with a cell set-up response to the radio network controller 8, saying that the cell is ready for addition of channels, such as for instance common control channels and traffic channels. However, usually some common control channels are set up already together with the cell, i.e. the cell is set up to a certain limit where system information can be transmitted within the cell coverage area. This addition may be performed by means of mapping frequencies from certain sectors of the ra- dio network controller 8. This mapping of channels onto the cell is not considered to be within the scope of the invention, and will therefore not be further described in this application.

An example of the additional information sent from the radio network controller 8 to the radio base station 1 is the previously mentioned common control channels, which are necessary for maintenance, cell search, paging and control of the traffic channels on which voice and data information from the users can be transmitted from one mobile terminal within the communication system to another.

When a cell has been established and channels are added, the radio base station 1 has a possibility to send (step 5) an indication message to the radio network con- troller 8 reporting on changes in resources and whenever applicable if errors have occurred, a so-called resource status indication message. This may be a message indicating new and operational channels. In accordance with the present invention, it is possible to use at least one variable in the standardised resource status indication message for the configuration of for instance cells, common control channels and traffic channels.

Variables that can be used for the above described purpose are named "resource operational state" and "availability status". By sending an information message to the radio network controller 8 denoting "resource operational state" = "disabled" and "availability status" = "off-line" or "not installed", the radio network controller 8 is notified about the current cell status and is aware of that the cell being in a pre- configuration state. Hereby, the radio network controller 8 will realise that virtual configuration can continue, although essential hardware components for a tradi- tional real configuration may be missing, which components in prior known configuration procedures would be an absolute prerequisite for performing the configuration of a cell.

There are several conceivable ways of transferring the parameters "resource opera- tional state" and "availability status" from the radio base station 1 to the radio network controller 8. One way of doing it, and hence in accordance with a first embodiment, is to append the parameter values to the standardised information message "resource status indication". Here, the 3GPP standard document UMTS 25.433 is incorporated by reference. This way of transferring the parameters requires the "resource status indication" to be sent to the radio network controller 8 immediately after the "call set-up response" message or immediately after the "common transport channel set-up response" message, both of which are standardised in the previously mentioned 3 GPP standard document.

A second way, and hence according to a second embodiment of the present invention, of transferring the required parameters is to do it in a similar way to the above described, but with the variables "resource operational state" and "availability status" added to the local cell information part. This results in that the radio network controller 8 is informed and thus becomes aware of that essential hardware is missing deliberately, and that the essential hardware will be installed later.

According to a third embodiment, the radio network controller 8 is informed about the pre-configuration state by adding at least one of the two variables "resource operational state" and "availability status" to the response signal transferred (step 4) at the set-up of a cell and a common transport channel. In such a case, the variables notify the radio network controller 8 that the configuration is turning out well, although certain essential hardware has not yet been installed.

Claims

1. A method in a telecommunications system of configuring a radio base station (1) by means of parameter interchange between the radio base station (1), a central configuration management unit (10) and a radio network controller (8), wherein standardised common parameters are interchanged when configuring cells and common control channels, both relating to the radio base station (1), the method characterised by the steps of: setting up at least one local cell by means of the radio base station (1) interacting with other units; transmitting a cell set-up response message and/or a common transport channel set-up response message from the radio base station (1) to the radio network controller (8); transmitting indications of resource operational state and/or availability status from the radio base station (1) to the radio network controller (8); and responding by transmitting, from the radio network controller (8) to the radio base station (1) and in dependence of the indications, additional information for making the local cell operational.

2. A method according to claim 1, further characterised by the step of: adding parameters concerning resource operational state and/or availability status of a local cell to the radio network controller (8) before completion of the configuration.

3. A method according to claim 1 or 2, characterised by the step of: appending parameters concerning resource operational state and/or availability status to a response signal used at set-up of a cell before completion of the configuration.

4. A method according to claim 1 or 2, characterised by the step of: appending parameters concerning resource operational state and/or availability status, to a common transport channel set-up response message.

5. A telecommunication system for configuration of a radio base station (1) and its cells and channels, the system comprising means for carrying out the method in accordance to anyone of the preceding claims.