WO2007132158A1

WO2007132158A1 - Base transceiver station

Info

Publication number: WO2007132158A1
Application number: PCT/GB2007/001602
Authority: WO
Inventors: Stuart Shutt; Richard Bailey; Alan Stidwell; Iain Stanbridge
Original assignee: Orange Sa
Priority date: 2006-05-11
Filing date: 2007-05-03
Publication date: 2007-11-22
Also published as: GB2438011A; GB0609377D0; GB2438011B

Abstract

A mobile radio network for providing a communications facility to mobile user equipment includes a plurality of base transceiver stations. One or more of the base transceiver stations includes a plurality of distributed transceiver units (54) associated with a plurality of user premises, a replicator (82) and a combiner (90). The replicator (82) receives the data f:rom the logical communications channels for the mobile user equipment which are affiliated with the base transceiver station, reproduces a plurality of versions of the data provided to the base transceiver station by the logical communications channels and communicates to each of the plurality of distributed transceiver units one of the versions of the data from the logical communications channels. Each of the distributed transceiver units (54) transmits the data received from the logical communications channels via the radio access interface to one or more of the mobile user equipment which are within a radio coverage area of the distributed transceiver unit (54). Each of the distributed transceiver units (54) receives data transmitted from one or more of the mobile user equipment via the radio access interface, and communicates the data received from the one or more mobile user equipment to a combiner (90). The combiner (90) receives the data from each of the distributed transceiver units (54) and combines the data to form the logical communications channels for communication from the base transceiver station via the communications interface.

Description

BASE TRANSCEIVER STATION

Field of the Invention

The present invention relates to mobile radio networks which are operable to provide a facility for mobile communications to mobile user equipment, and include a plurality of base transceiver stations, each of the base transceiver stations being operable to transmit and receive data to and from the mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station.

The present invention also relates to base transceiver stations for mobile radio networks and to methods of providing a mobile communications to mobile user equipment. Background of the Invention

Mobile radio networks include a plurality of base transceiver stations which are deployed over a geographical area to provide a facility for communications to mobile user equipments. Each of the base transceiver stations provides a radio coverage area within which data can be transmitted to and received from mobile user equipment using radio signals, within a transmission and reception range of the coverage area, the radio signals being transmitted and received according to a radio access interface.

The number of users which can be supported by a base transceiver station should be as high as possible in order to make most efficient use of radio and network resources. Typically a greater number of users than physical channels can be supported by a base transceiver station for a conventional deployment in which a base transceiver station serves a coverage area of some several square kilometres, conventionally referred to as a macro cell. Thus by a so called "trunking efficiency" a greater number of users of the mobile user equipment are supported within the coverage area than the number of physical communications channels. Furthermore, a base transceiver station is normally deployed to the effect that the radio coverage area provided will reach as many users as possible. Therefore, typically a number of users within a cell served by the base transceiver station is large enough to utilise the radio and network resources to an extent that makes the deployment of such base transceiver stations economically viable.

Typically, a design of the radio access interface will require that a minimum number of logical channels can be provided to a base transceiver station. For example, the Global System for Mobiles (GSM), which provides a Time Division Multiple Access (TDMA) radio access interface, divides an available frequency band into different frequency channels, each frequency channel providing eight physical channels through eight TDMA time slots. As such, a minimum configuration for a deployment of a single frequency channel will provide seven logical traffic channels and a logical broadcast channel (BCCH), using the eight TDMA time slots. Therefore, if a base station is configured to provide a minimum number of traffic channels which is possible with a radio access interface and deployed for relatively short range communications over a small coverage area, then in accordance with a typical distribution and profile of mobile users, it may be difficult to make efficient use of the radio and network resources. Such a deployment is typical of a so called Pico-cell. For this reason, conventionally Pico-cell deployments have been less attractive to network operators.

It is therefore desirable to provide an improvement to mobile radio networks and in particular to base transceiver stations which can make a more efficient use of radio and network resources such as usage of a single radio frequency, for example where a base station is configured to provide a minimum number of channels which can be provided by a radio access interface of a mobile telecommunications standard.

Summary of the Invention

According to the present invention there is provided a mobile radio network operable to provide communications to mobile user equipment, the mobile radio network including a plurality of base transceiver stations. Each of the base transceiver stations is operable to transmit and receive data to and from mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station. The data is provided selectively to the base transceiver stations and received from the base transceiver stations via a communications interface comprising a plurality of logical communications channels which are assigned to the mobile user equipment affiliated to the base transceiver stations. One or more of the base transceiver stations is adapted to include a plurality of distributed transceiver units associated with a plurality of user premises, a replicator and a combiner. The replicator is operable to receive the data from the logical communications channels for the mobile user equipment which are affiliated with the base transceiver station, to reproduce a plurality of versions of the data provided to the base transceiver station by the logical communications channels and to communicate to each of the plurality of distributed transceiver units one of the versions of the data from the logical communications channels. Each of the distributed transceiver units is operable to transmit the data received from the logical communications channels via the radio access interface to one or more of the mobile user equipment which are within a radio coverage area of the distributed transceiver unit. Each of the distributed transceiver units is operable to receive data transmitted from one or more of the mobile user equipment via the radio access interface, and to communicate the data received from the one or more mobile user equipment to a combiner. The combiner is operable to receive the data from each of the distributed transceiver units and to combine the data to form the logical communications channels for communication from the base transceiver station via the communications interface to the mobile network.

According to embodiments of the present invention a base transceiver station is provided with a plurality of distributed transceiver units each of which can be deployed within a user's premises. Within the user's premises the transceiver unit can be arranged to provide a relatively short range communications, transmitting and receiving radio signals with a relatively low power to and from the mobile user equipment. A replicator is arranged to reproduce the data received via logical communications channels for transmission to one or more mobile user equipment which would be communicated on a conventional logical transceiver unit provided within a conventional base station with which the mobile user equipment are affiliated. By providing a plurality of distributed transceiver units in place of a single logical transceiver a substantial increase in the efficiency and utilisation of radio and network communication resources can be provided. This is because a greater number of users can be served than may be possible with a conventional base station. For example, a short range low power deployment of a base transceiver station such as for a Pico-cell, with a minimum configuration, which can be provided for a standardised radio access interface, provides a minimum number of logical communication channels. However this number may be higher than a number of channels which can be economically supported for a number of users which can be reached for such a short range deployment.

Typically mobile radio networks are designed to the effect that a minimum possible number of logical communications channels are provided by each base transceiver station in order to provide a necessary efficiency in the utilisation of the radio communications resources. If this minimum number is provided for short range communications, such as to a Pico cell, for example, which by its nature can only serve a limited number of users, then a rate of use of radio network resources may not make the deployment of Pico cells attractive, because a network operator cannot recover sufficient revenue from users within the Pico cell to justify the expense of the radio and network communications resources consumed. This is not only because the Pico cell by its nature provides a relatively short range communication facility, but because a minimum number of logical communications channels which must be deployed with respect to the radio access interface standard is substantially greater than a number which can make economical use of the radio and network resources which are consumed, with respect to a number of users which can be reached by such a deployment.

Embodiments of the present invention can therefore provide a facility for making such Pico cell deployments economically justifiable. This is because the data received by a base transceiver station and sent from the base transceiver station via logical communication channels is transmitted to and received from the mobile user equipment by a combination of a radio access interface and a data communications link to the user premises in a way which limits the mobile network resources required to provide this capacity. In one example, the data communications link is a digital subscriber line such as that which is available to users' homes, which are conventionally used for delivering fixed line telephony services and cable television. In another example, the digital subscriber line may be supported by a broadband communications channel and may operate in accordance with the internet protocol. Thus, the logical communications channels are delivered via digital subscriber lines to each of the user's premises, providing user data and signalling data, and then communicated to and from the mobile user equipment via a radio access interface formed locally at the user's premises. As a result the number of users which can be reached by a base transceiver station can be substantially increased by replicating the logical data (in the down-link) and communicating the data digitally to the user's premises for short range radio communications via a radio access interface.

According to the present invention therefore, a plurality of distributed transceiver units replaces a logical transceiver unit which would be deployed within a conventional base station. Various further aspects and features of the present invention are defined in the appended claims.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which like parts are provided with the same reference numerals and in which: Figure 1 is a schematic block diagram of a mobile radio network according to the Global System for Mobiles;

Figure 2 is a schematic block diagram of a conventional deployment of a base transceiver station serving a Macro cell;

Figure 3 a is schematic block diagram of a transmitter chain which is arranged to transmit data received from logical communications channels to mobile user equipment, via a radio access interface in accordance with the GSM standard; Figure

3b is a schematic block diagram of a receiver chain which is arranged to receive data from radio signals transmitted in accordance with the GSM radio access interface;

Figure 4 is a schematic illustration of logical communications channels, which are presented on communications interface between a base station controller and a base transceiver station; '

Figure 5 is a schematic block diagram of a base transceiver station deployed in accordance with an example embodiment of the present invention;

Figure 6a is a schematic block diagram illustrating parts which make up a down-link communication of data by the base transceiver station shown in Figure 5; and Figure 6b is a schematic block diagram illustrating parts which make up an up-link communication of data by the base transceiver station shown in Figure 5;

Figure 7a is a schematic block diagram illustrating parts which make up a transmitter chain of one of the distributed transceiver units shown in Figure 5; Figure 7b is a schematic block diagram illustrating parts which make up a reception chain of one of the distributed transceiver units shown in Figure 5;

Figure 8 is a schematic block diagram illustrating an example in which a mobile user equipment performs a hand over from a base transceiver station in accordance with an embodiment of the present invention to a conventional base transceiver station; Figure 9 is flow diagram illustrating a process of communicating data to mobile user equipment performed by the base transceiver station in accordance with an embodiment of the present invention;

Figure 10 is a flow diagram illustrating a process through which data is received by a base transceiver station in accordance with an embodiment of the present invention.

Description of Example Embodiments

Embodiments of the present invention find application with a mobile radio network in which data is transmitted to and received by mobile user equipment from base transceiver stations deployed throughout the network, and is not dependent on any one radio access technology. One example embodiment of the present invention will be explained with reference to the Global System for Mobiles (GSM). However, it will be appreciated that embodiments of the present invention find application with any mobile radio network in particular with a General Packet Radio System (GPRS) network (GPRS/GSM or GPRS/UMTS) or a CDMA network such as WCDMA, 3GPP or CMDA2000.

Embodiments of the present invention find particular application with mobile radio networks in which a minimum configuration of a base transceiver station requires that a fixed minimum number of logical communications channels are deployed to any base transceiver station. Figure 1 provides a schematic block diagram of a conventional mobile radio network in accordance with the GSM architecture. In Figure 1 a Mobile Switching Centre (MSC) 1 is connected to a Public Switched Telephone Network (PSTN) 2 which forms an external link from the mobile radio network to other terminals which maybe connected to a fixed wire line telecommunications network. A Home Location Register (HLR) 4 and an Operation Maintenance Centre (OMC) 6 are connected to the MSC 2 and provide system support to allow roaming of mobile user equipment and monitoring and support functions for the mobile radio network which those familiar with GSM will be acquainted. Connected to the Mobile Switching Centre 2 via a Trans-coding Rate Adaptation Unit (TRAU) 10 are a plurality of base station controllers 12. Although only two base station controllers 12 are shown it will be appreciated that any number of base station controllers can be provided within a mobile radio network. The base station controllers 12 perform a function of communicating data received on logical channels from the MSC via a TRAU 10 and selectively distribute the data from these logical channels to a plurality of base transceiver stations 14 for communication to the mobile user equipment and to receive the data from the mobile user equipment and to transmit the data to the MSC 1. Thus, the base station controllers 12 provide an arrangement for communicating selectively data on logical channels to the base transceiver stations 14 in order to communicate data to and from one or more mobile user equipment which are affiliated with the base transceiver stations 14.

An illustration of data communicated on logical channels is shown graphically by a grid 16 each element of which represents a logical channel through which data is communicated on an interface between the base station controller 12 and the base transceiver station 14. As will be appreciated by those skilled in the art, the interface between the base station controller and the base transceiver station is known as the Atø_s interface. The corresponding interface in the UMTS architecture is the I₁₁J₃ interface. A more detailed illustration of a deployment of a base transceiver station 14 is shown in Figure 2.

In Figure 2 a base transceiver station 14 receives data via logical channels on the communications interface between the base station controller and the base transceiver station Abis 20 and to communicate data via a radio access interface to and from the mobile user equipment. The data is encoded and modulated on to a radio frequency carrier to transmit the data to mobile user equipment (UE) 24 via an Antenna 26.

Also shown in Figure 2 is a schematic illustration of a plurality of transceivers 28 which form part of the base transceiver station 14. Each of the transceivers 28 is arranged to serve a logical frequency channel, formed by dividing an allocated radio frequency spectrum and assigning each frequency division to each of the frequency channels. The transceivers 28 provide a logical division of frequency with the effect that each tfansceiver 28 is assigned a separate frequency channel. However, as will be appreciated the GSM system implements frequency hopping either at base band in that data is transmitted on a different one of the Transceivers 28 or after modulation onto the radio frequency carrier with the effect that the frequency of the radio frequency carrier is changed in accordance with a hopping sequence. Hence the allocation of frequency channels to the transceivers 28 is logical.

Figures 3a and 3b provide an illustration of transmitter and receiver chains which represent a conventional transmission and reception of data by one of the transceivers 28. In Figure 3a data received via the logical communications channels via the communications interface 20 is processed at a base band de-multiplexer 30. The base band de-multiplexer is arranged to present the data received from the logical communications channels to the transceivers 28 for communication to the mobile user equipment via the radio access interface, The data from the de-multiplexer is therefore presented to a data processing and modulation unit 32. The data processing and modulation unit 32 divides the data into frames so that the data can be interleaved and transmitted as bursts which according to the example of GSM is transmitted on one of eight time slots into which to a Time Division Multiple Access (TDMA) frame is divided, as those acquainted with GSM will appreciate. Accordingly, the burst of data is transmitted in one of the time slots, by modulating the data onto a radio frequency carrier using a radio frequency modulator 34, for up conversion to the radio frequency carrier signal before being amplified by the radio frequency amplifier 36 and transmitted via an antenna 38. Thus as illustrated schematically in one example seven GSM traffic channels TCH are provided within a TDMA frame 40 along with a control channel known as the broadcast control channel BCCH. Correspondingly Figure 3b illustrates a receiver chain for receiving radio signals represent the data from the traffic channels transmitted on the TDMA frame 40 and converting this data into logical channels for presentation on the communications interface from the base transceiver station to the base station controller 22. The radio signals received via an antennae 38 in accordance with the GSM radio access interface 40 are detected by a radio frequency front end 42 and down converted and demodulated by an intermediate frequency de-modulator 44 and presented in complex base band form to a data processing and de-modulation processor 46. The data processing and de-modulation processor 46 de-modulates the complex base band signal to produce base band data, performs de-interleaving and combines the data to reproduce the logical data transmitted by the mobile user equipment. Finally, the data is formed by a base band processor 48 by multiplexing data received from the data processing and de-modulation processor 46 into the logical channels for communication via the communications interface 22 to the base station controller.

Figure 4 provides as a graphical illustration a grid corresponding to that shown in Figure 1, which represents the logical communication of data via logical channels between the base station controller and the base transceiver station. As can be seen this is made up of traffic channels TCH, signalling data Tsig and data communicated by the operational maintenance centre OMC.

Returning to Figure 2, the base transceiver stations 14 provide a coverage area 25 formed by transmitting and receiving radio signals from the antennae 26 to the mobile user equipment 24 within range of the antenna 26. As illustrated in Figure 3a and Figure 3b each transceiver 28 within the conventional base transceiver station 14 must support a minimum of eight physical traffic channels formed on a frequency channel which is assigned to that transceiver 28. As such, if a base station were to be deployed, the minimum number of logical traffic channels which can be deployed to the base transceiver station is seven. If the base transceiver station is only to serve a relatively small number of users such as for example if the base transceiver station is to form a Pico cell then the radio resources and network capacity required to deploy the minimum number of seven channels may not make such a deployment economically viable for a small number of users. Accordingly, embodiments of the present invention provide an arrangement in which a base transceiver station can be deployed in a way which makes more efficient use of radio and network resources and therefore can make deployment of a base transceiver station with a minimum number of channels economically viable. An embodiment of the present invention is illustrated in Figure 5.In Figure 5 a multiplexer 51 forming part of the base transceiver station for the GSM standard receives data via a logical communications interface (Abis) providing logical communications channels 52 as represented and illustrated in Figure 4 for a conventional base transceiver station. In accordance with an example of the present technique a plurality of distributed transceiver units 54 replace a conventional transceiver 28 of the conventional base transceiver station shown in Figure 2. The distributed transceiver units 54 are deployed within the user premises such as houses 56 and provide relatively short range communications within these houses to mobile user equipment 58.

In accordance with the present technique the data from the logical communications channels are communicated digitally in base band form via a fixed line, for example a digital subscriber line 60 to the distributed transceiver units 54. Correspondingly, data received from the mobile user equipment via the radio access interface by the distributed transceiver units 54 are communicated back to the multiplexer 51 via the fixed line 60. The base transceiver station of Figure 5, according to the present technique therefore does not perform communication of data to and from the mobile user equipment using radio signals alone.

As illustrated in Figures 6a and 6b, the present technique arranges for the data from the logical communications channels which would conventionally be transmitted by a transceiver 28 as shown for the base station 14 in Figure 2, to be reproduced and transmitted to the distributed transceiver units 54 at which point the data in converted into radio signals and communicated via the radio access interface formed in the same way as that for a conventional operation of a base transceiver station. This communication will be explained in the following paragraphs.

In Figure 6a the data is received from the logical communications channels at a data converter 50. The data converter removes parts of the data associated with operation and maintenance. The data for communication to the mobile user equipment is then extracted and sent to a replicator 82. The data for communication to the mobile user equipment will be for one or more mobile user equipment which are affiliated with the base transceiver station and any signalling information such as, for example the broadcast control channel (BCCH). The data is sent to the replicator 82 at which point the replicator 82 simply copies that data and communicates each copy as if it were the original copy provided by the data converter 50 on an interface channel 84 to each of the distributed transceiver units 54 via the digital subscriber line 60. That is, as shown in Figure 6a the data is communicated as if this were the data from the logical channels shown in Figure 4, (with perhaps a reduction of the data associated with operations and maintenance) via a transmitting and receiving modem 86, 88 via the digital subscriber line 60 to the distributed transceiver units 54. The distributed transceiver units 54 then generate the radio access interface by converting the data received from the logical communications channels into radio signals as illustrated by the TDMA structure 40. Thus as illustrated in Figure 7a a transmitter chain within the distributed transceiver unit 54 includes a data processing modulation unit 100, an IF modulator 102 and an radio frequency amplifier 104 which operates substantially in the same way as the data processing modulation unit 30 the IF modulator 34 and the radio frequency amplifier 36 described above for a conventional base transceiver station with reference to Figure 3. Returning to Figure 6b for the receiving chain, each of the distributed transceiver units 54 may receive radio frequency signals transmitted from one or more mobile user equipment within range of the distributed transceiver unit 54. However, collectively the distributed transceiver units 54 can only accommodate a number of physical channels corresponding to the number which would have been supported by the transceiver 28 within a conventional base transceiver station. Thus, for the example of GSM, collectively the plurality of distributed transceiver units 54 can only support seven traffic channels assuming that the base transceiver station in accordance with the example embodiment is only transmitting on a signal frequency channel which would otherwise be performed by signal transceiver 28. Therefore as shown in Figure 6b the radio frequency signals received by the distributed transceiver units 54 are converted into logical channels and in dependence upon which of the physical traffic channels have been assigned by those distributed transceiver units 54 will form this user data on a corresponding logical channel which will then be communicated to a combiner unit 90 via transmitting and receiving modems 92, 94 and the digital subscriber line 60. At the combiner 90 the data received from each of the logical channels formed by the transceiver units 54 is combined into a composite form, to recreate the data in accordance with the logical channels which would have been produced by the transceiver 28 in a conventional base transceiver station 14. Thus, the combiner 90 at its output will form an arrangement of data on logical channels as represented for example by the graphical representation in Figure 4 and reproduced illustratively in Figure 6b as a collection of channels 95. Thereafter, the data from the logical channels is presented to the data converter 50 for communication via the communications interface 52 to the base station controller 12. Thus as illustrated in Figure 6b in accordance with the present technique the traffic channels, which have been allocated to the mobile user equipment will receive radio signals representing data on the up-link from the mobile user equipment, although the mobile user equipment may be transmitting the radio signals to different distributed transceiver units. The distributed transceiver units will not be aware of the physical channels (time slots) which are used by other distributed transceiver units, because the time slots are allocated collectively to all the mobile user equipment served by the base transceiver station. Thus time slots in the TDMA frame may receive radio signals from mobile user equipment which are transmitting to the same distributed transceiver unit or different transceiver units, under the control of the BSC. This is because the distributed transceiver units are replicating the same radio access interface. For up-link communications therefore the assignment of physical channels to mobile user equipment is independent of the transceiver units via which those mobile user equipment are communicating.

Figure 7b provides an illustration of the receiver chain formed by the distributed transceiver unit 54. Essentially, the receiver chain is arranged in correspondence with the receiver chain shown in Figure 3b. Received radio frequency signals from the mobile user equipment 58 are down converted by a radio frequency front end 106, demodulated by a radio frequency demodulator 108 and passed to a data processing and demodulation unit 110. The data processing demodulation unit 110 recovers the data from each of the traffic channels, de-interleaves the data, decodes that data and forms that data into logical channels for communication to the combiner 90 via the transmitting modem 92.

In some examples the mobile radio network will require that the base stations are synchronised to the extent that the transmission and reception of signal by the mobile user equipment corresponds to a physical timing. As a result, if the mobile user equipment changes affiliation from one base station to another the communication of data via the radio access interface can be co-ordinated to the effect of maintaining communication whilst the change of affiliation is taking place. To this end, the distributed transceiver units in accordance with the present technique will be provided with a synchronisation signal. The synchronisation signal will then synchronise for example the TDMA frames regenerated by the distributed transceiver units which will have a corresponding timing to that of other base transceiver stations throughout the mobile radio network. As will be appreciated there are various ways in providing this synchronisation signal and embodiments of the present invention are not limited to one particular form of the synchronisation signal. In one example the synchronisation signal is provided by a private wire emulation circuit although in other examples the signal could be a Global Position System signal received by a satellite receiver.

As illustrated in Figure 8, if the distributed transceiver units are synchronised with respect to other base stations within the mobile radio network, if the mobile user equipment 58 moves outside a coverage area provided by the distributed transceiver unit 54 then communication can be maintained via a Macro cell formed by the conventional base station 14. Thus as illustrated in Figure 8, as the mobile user equipment 58 moves outside the user premises 56 and therefore outside a radio coverage area provided by the distributed transceiver unit 54, the mobile user equipment 58 can hand over to the base transceiver station 14 providing the radio coverage area 25, because the base transceiver station 14 and the distributed transceiver units are synchronised.

In order to avoid the digital subscriber lines communicating data unnecessarily, if the distributed transceiver unit receives a signal which is below a predetermined threshold then no data is transmitted for that channel. Since the logical channels are replicated via each of the distributed transceiver units many of those channels will not be communicating data. Furthermore, in order to avoid communicating data on the digital subscriber line when no data is being transmitted by the mobile user equipment such as, for example during silence periods then the predetermined threshold is set so that no data is transmitted over the digital subscriber line 60 as shown in Figure 6b during such periods. Summary of Operation

A summary of the operation of the base transceiver station in accordance with the present technique will now be described with reference to two flow diagrams shown in Figures 9 and 10. Figure 9 shows a transmission process for transmitting data on the logical channels to the mobile user equipment via the distributed transceiver units. Figure 10 shows a reception process for recovering data transmitted by the mobile under equipment via the radio access interface and forming that data into logical communications channels for communication from the base transceiver station to the base station controller. Figure 9 is summarised as follows :-

Sl: Data received ftom the base station controller via logical communications channels is formed into logical channels for communication to the distributed transceiver units. S2: Data from the logical communications channels is then replicated to produce the version of the data in accordance with the logical communications channels for communication to the distributed transceiver units.

S4: Each replicated version of the data is then communicated to one of the distributed transceiver units, one of the replicated versions being received by each of the distributed transceiver units. The data is communicated in the form which allows ^' that data to be associated with the logical communications channel in which it is being transmitted so that, for example, user data for communication to a particular mobile user equipment within the coverage area of the distributed transceiver unit can be identified from that logical channel and communicated via a physical radio channel to that mobile user equipment.

S6: The distributed transceiver units then reproduce the radio access interface by generating radio signals in accordance with the radio access interface standard so that the data received on the logical communications channels can be communicated to the mobile user equipment for which it is intended via a corresponding physical radio channel.

In order to receive data transmitted by the mobile user equipment within a coverage area of each of the distributed transceiver units and to convert that data into logical communications channels for communicating from the base transceiver station a reception process is performed which is illustrated in Figure 10 and summarised as follows: -

S8: The radio signals which are transmitted by one or more mobile user equipment in accordance with the radio access interface standard within range of a distributed transceiver unit are received by that distributed transceiver unit. SlO: The data transmitted by the mobile user equipment within range of the distributed transceiver unit is then recovered from the radio frequency signals and formed into logical communications channels providing data from the one or more mobile user equipment. The data may be signalling data as well as user data.

S 12: Each of the distributed transceiver units then communicates the data recovered from the one or more mobile user equipment within its coverage area in the form of logical communications channels to a combiner in a form which reflects the logical channel on which the data is received. Thus, the data from a particular mobile user equipment is received by a distributed transceiver unit is represented on one of the logical communications channels which is assigned to that mobile user equipment.

S 14: At the combiner, the data received from each of the distributed transceiver units on each of the logical communications channels is combined to form a set of logical channels in accordance with the communications interface which is conventionally formed from the base transceiver station to the base station controller. Thus the combiner forms the data from a logical channel into a composite signal as if the data were communicated from a conventional transceiver of a base transceiver station for communication onto a base station controller. As will be appreciated the present invention finds application with any form of mobile radio network. However, the present technique provides an advantage for example, where a structure of the radio access interface requires that a minimum number of communications channels be assigned to any one frequency so that by replicating the transmission and reception channels at each of a plurality of distributed transceiver units and communicating the data in digital form to those transceiver units a greater number of users can be supported than would otherwise be the case if the base stations were physically located in the end user premises. Therefore, in combination with a trunking efficiency a greater number of users can be supported using a base transceiver station in accordance with the present technique, which can therefore make more economical use of this minimum number of channels.

Various further aspects and features of the present invention are identified in the appended Claims.

As will be understood various modifications and changes may be made to the embodiments of the present invention described above without departing from the scope of the appended Claims. As will be appreciated depending on the type of mobile radio network it may be necessary to communicate both user and signalling data to the distributed transceiver units in order to provide an operational radio access interface. For the example of the Global System for Mobiles a minimum configuration of a single logical transceiver would require that the BCCH channel is broadcast as a logical channel so the logical data communicated to the distributed transceiver units contains a BCCH Channel.

Claims

1. A mobile radio network for providing communications to mobile user equipment, the mobile radio network including a plurality of base transceiver stations, each of the base stations being operable to transmit and receive data to and from the mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station, the data being provided selectively to the base transceiver stations and received from the base transceiver stations via a communications interface comprising a plurality of logical communications channels which are assigned to the mobile user equipment affiliated with the base transceiver stations, wherein one or more of the base transceiver stations is adapted to include a plurality of distributed transceiver units associated with a plurality of user premises, and a replicator operable to receive the data from the logical communications channels for the mobile user equipment which are affiliated with the base transceiver station, to reproduce a plurality of versions of the data and to communicate to each of the plurality of distributed transceiver units one of the versions of the data from the logical communications channels, wherein each of the distributed transceiver units is operable to transmit the data received from the logical communications channels via the radio access interface to one or more of the mobile user equipment which are within a radio coverage area of the distributed transceiver unit, and each of the distributed transceiver units is operable to receive data transmitted from one or more of the mobile user equipment via the radio access interface, and to communicate the data received from the one or more mobile user equipment to a combiner, the combiner being operable to receive the data from each of the distributed transceiver units and to combine the data to form the logical communications channels for communication from the base transceiver station via the communications interface.

2. A mobile radio network as claimed in Claim 1, wherein the data is communicated to the distributed transceiver unit from the replicator and from the distributed transceiver unit to the combiner via a fixed line.

3. A mobile radio network as claimed in Claim 2, wherein the fixed line is a digital subscriber line.

4. A mobile radio network as claimed in Claim 1, 2 or 3, wherein the distributed transceiver units are operable to detect a signal strength with which radio signals are received, and only to communicate the data recovered from the radio signals to the combiner, if the signal strength of the received radio signals is above a predetermined threshold. ^• .

5. A mobile radio network as claimed in any preceding Claim, wherein each of the plurality of base transceiver units includes a synchronisation controller operable to receive a synchronisation signal for synchronising the transmission of radio signals to the mobile user equipment with the transmission of radio signals to mobile user equipment from others of the base stations in the mobile radio network and for synchronising the reception of the radio signals from the mobile user equipment with the reception of the radio signals from mobile equipment at others of the base stations in the mobile network.

6. A method of providing communications to mobile user equipment, the method comprising providing selectively to each of a plurality of base transceiver stations data for communication to mobile user equipment affiliated to the base transceiver stations, via a communications interface comprising a plurality of logical communications channels which are allocated to the mobile user equipment affiliated to the base stations, and receiving from the base transceiver stations data received by the base transceiver stations from the mobile user equipment in accordance with the logical communications channels, transmitting and receiving data from and to the base transceiver stations to and from mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station, the transmitting the data to the mobile user equipment comprising receiving the data from the logical communications channels, reproducing a plurality of versions of the data received from the logical communications channels, and communicating to each of a plurality of distributed transceiver units one of the versions of the data from the logical communications channels, the plurality of distributed transceiver units being associated with user premises, transmitting the data received from the logical communications channels to one or more of the mobile user equipment via the radio access interface which are within range of the distributed transceiver unit, and the receiving data from the mobile user equipment comprising receiving at each of the distributed transceiver units data transmitted from the one or more mobile user equipment via the radio access interface, communicating the data received at the distributed transceiver units from the mobile communications equipment to a combiner, and combining, at the combiner, the data received by each of the distributed transceiver units from the one or more mobile user equipment in accordance with one or more of the logical communications channel assigned to the one or more mobile user equipment.

7. A method as claimed in Claim 6, wherein the communicating the data according to the logical communications channels to and from the distributed transceiver units for communication to or from the one or more mobile user equipment, includes communicating the data via a fixed line.

8. A method as claimed in Claim 6 or 7, comprising detecting a signal strength with which radio signals are received at the distributed transceiver units, and only communicating data recovered from the received radio signals to the combiner, if the signal strength of the received signals is above a predetermined threshold.

9. A method as claimed in any of Claims 6, 7 or 8, comprising receiving a synchronisation signal at each of the distributed transceiver units for synchronising the transmission of radio signals to the mobile user equipment with the transmission of radio signals to mobile user equipment from others of the base stations in the mobile radio network, and for synchronising the reception of the radio signals by the base transceiver unit from mobile equipment with the reception of radio signals at others of the base stations in the mobile network.

10. A base transceiver station for a mobile radio network, the base transceiver station comprising a plurality of distributed transceiver units associated with a plurality of user premises, and a replicator operable to receive data from logical communications channels, the logical communications channels providing the data for transmission to mobile user equipment via a radio access interface, to reproduce a plurality of versions of the data received from the logical communications channels and to communicate to each of the plurality of distributed transceiver units one of the versions of the data from the logical communications channels, wherein each of the distributed transceiver units is operable to transmit the data received from the logical communications channels, via the radio access interface to one or more of the mobile user equipment which are within a radio communications range of the distributed transceiver unit, and each of the distributed transceiver units is operable to receive data transmitted from one or more of the mobile user equipment via the radio access interface, and to communicate the data received from the one or more mobile user equipment to a combiner, the combiner being operable to receive the data from each of the distributed transceiver units and to combine the data to form the logical communications channels for communication from the base transceiver station.

11. A base transceiver station as claimed in Claim 10, wherein the data according to the logical communications channels is communicated to one or more of the distributed transceiver units from the replicator and communicated from one or more of the distributed transceiver units to the combiner via a fixed line.

12. A base transceiver station as claimed in Claim 10 or 11, wherein the distributed transceiver units are operable to detect a signal strength with which radio signals are received, and only to communicate data recovered from the received radio signals to the combiner, if the signal strength of the received signals is above a predetermined threshold.

13. A base transceiver station as claimed in Claim 10, 11 or 12, wherein each of the plurality of base transceiver units includes a synchronisation controller operable to receive a synchronisation signal for synchronising the transmission of the radio signals to the mobile user equipment with the transmission of radio signals to mobile user equipment from others of the base stations in the mobile radio network and for synchronising the reception of the radio signals by the base transceiver unit from the mobile user equipment with the reception of radio signals from mobile equipment at others of the base stations in the mobile network.

14. A distributed transceiver unit for use with the base transceiver station of any of Claims 10 to 13, comprising a data receiver operable to receive data from logical communications channels, the logical communications channels providing the data for transmission to mobile user equipment via a radio access interface, the data being one of a plurality of versions of the data reproduced in accordance with the logical communications channels, a radio transmitter for transmitting the data received from the logical communications channels to one or more of the mobile user equipment which are within a radio communications range of the distributed transceiver unit, the data being transmitted in accordance with a radio access interface provided by the base transceiver station, a radio receiver for receiving data transmitted from the one or more mobile user equipment via the radio access interface, and a data communications apparatus for communicating the data received from the one or more mobile user equipment to a combiner, in accordance with the logical communications channels for communication from the base transceiver station, the data being communicated to the combiner and received from the replicator via a fixed line.

15. A replicator for use with the base transceiver station according to any of Claims 10 to 14, the replicator comprising a data receiver for receiving data from logical communications channels, the logical communications channels providing the data for transmission to mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station, a data reproducing apparatus operable to reproduce a plurality of versions of the data in accordance with the logical communications channels and to communicate to each of a plurality of distributed transceiver units one of the versions of the reproduced data from the logical communications channels, wherein the data is communicated to the distributed transceiver .units via a fixed line.

16. A combiner for use with the base transceiver station according to any of Claims 10 to 15, a receiver operable to receive data from each of a plurality of distributed transceiver units, the data being received from the distributed transceiver units in accordance with one or more of the logical communications channels assigned to the one or more mobile user equipment, and a combining processor operable to combine the data to form the logical communications channels for communication from the base transceiver station via the communications interface.

17. An apparatus for providing communications to mobile user equipment, the apparatus comprising means for providing selectively to each of a plurality of base transceiver stations data for communication to mobile user equipment affiliated to the base transceiver stations, via a communications interface comprising a plurality of logical communications channels which are allocated to the mobile user equipment affiliated to the base stations, and receiving from the base transceiver stations data received by the base transceiver stations from the mobile user equipment in accordance with the logical communications channels, means for transmitting and receiving data from and to the base transceiver stations to and from mobile user equipment via a radio access interface within a radio coverage area provided by the base transceiver station, the means for transmitting the data to the mobile user equipment comprising means for receiving the data from the logical communications channels, means for reproducing a plurality of versions of the data received from the logical communications channels, and means for communicating to each of a plurality of distributed transceiver units one of the versions of the data from the logical communications channels, the plurality of distributed transceiver units being associated with user premises, means for transmitting the data received from the logical communications channels to one or more of the mobile user equipment via the radio access interface which are within range of the distributed transceiver unit, and the receiving data from the mobile user equipment comprising means for receiving at each of the distributed transceiver units data transmitted from the one or more mobile user equipment via the radio access interface, means for communicating the data received at the distributed transceiver units from the mobile communications equipment to a combiner, and means for combining, at the combiner, the data received by each of the distributed transceiver units from the one or more mobile user equipment in accordance with one or more of the logical communications channel assigned to the one or more mobile user equipment.

18. A mobile radio network, a base transceiver station, a distributed transceiver unit, a replicator and a combiner substantially as herein before described with reference to Figures 5 to 8 of the accompanying drawings.

19. A method of providing a mobile communications facility substantially as hereinbefore described with reference to Figures 5 to 8 of the accompanying drawings.