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WIRELESS TELECOMMUNICATIONS SYSTEMS AND METHODS The invention relates to wireless telecommunications systems and methods. Embodiments of the invention, to be described below by way of example only, enable a mobile telecommunications unit (such as a mobile telephone handset) to be used for normal mobile telecommunications purposes in a mobile telecommunications network and, alternatively, to be used in the manner of a cordless handset within a confined environment such as a house, office or other building.
According to the invention, there is provided a wireless telecommunications network, comprising a plurality of base stations each for wireless communication with wireless terminals in geographical areas respectively served by the base stations, in which one of the geographical areas includes the interior of a building, and the base station ("the home base station") respective to that area is connected into the network by a broad or wideband link into the building.
According to the invention, there is further provided a base station for a wireless telecommunication network and which is associated with a processing unit for providing subscriber-type television services within a building via signals received over a broad or wideband link, the base station being connectable into the network via the broad or wideband link.
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According to the invention, there is still further provided a set-top box for providing subscriber-type television services within a building in combination with a base station for a wireless telecommunications network and for extending the coverage of the network into the building, the base station being connectable into the network via a broad or wideband link also supplying television services to the set-top box.
According to the invention, there is yet further provided a method of providing coverage within a building via a mobile telecommunications network comprising a plurality of base stations each for wireless communication with wireless terminals in geographical areas respectively served by the base stations, in which one of the geographical areas includes the interior of a building and including the step of connecting the base station ("the home base station") respective to that area into the network by a broad or wideband link into the building.
Mobile telecommunications systems and methods according to the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a block diagram of a known mobile telephone network such as a GSM network; Figure 2 is a block diagram of a known cordless telephone system such as used in houses,
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offices or other buildings; and Figure 3 is a block diagram of one of the systems according to the invention.
The known GSM network shown in Figure 1 comprises a mobile switching centre (MSC) 10 which is connected to and controls a number of base station controllers (BSCs) of which one, referenced 12, is shown. Each BSC controls a number of base stations (BSs) 14,15 each of which is a radio transceiver and provides telephone (and other telecommunication) service to mobile terminals (MTs) 16 (mobile telephone handsets, in particular) within a particular geographical area, termed a cell such as shown at 18 and 20, the geographical extent of which depends on local radio propagation characteristics. The MSC 10 is connected to the BSCs by communication links 22 (which may be landlines), and each BSC is connected to its respective BSs by further communication links 24, which again may be fixed links.
The MSC 10 is connected to the public switched telephone network (PSTN) 25 which provides service for fixed telephone handsets. Other mobile networks (such as shown at 26) may also be connected to the PSTN.
In known fashion, each MT 16 when powered on becomes registered with the local BS 14,15 (that is, the BS providing coverage to the geographical area or cell in which the MT is currently located). This registration is achieved by an exchange of signals between
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the BS and the MT. Via the BSC 12, each BS 14,15 thus advises the current locations of the MTs in its cell to the MSC, this information being stored in a home location register (HLR) and/or a visitor location register (VLR) (not shown). If a call is to be made to a particular MT, such as from a fixed handset in the PSTN for example, the call is directed by the PSTN to the MSC 10, using the telephone number of the MT. The MSC can then locate the particular MT from information in its HLR or VLR, and direct the call via the BSC 12 to the correct BS and thence to the particular MT. In the same way, a call to a particular MT can be received from a mobile terminal in another mobile network.
If an MT wishes to make a call to a fixed telephone in the PSTN or to a mobile terminal in the same or another mobile network, the call is directed via the BS of the calling MT's cell and is then routed via the BSC 12 and the MSC 10 to the called telephone.
When an MT moves from one cell into another cell, a hand-over procedure takes place by means of which the MT becomes de-registered from the BS of the previous cell and registered with the BS of the new cell.
The transmitting and receiving frequencies used within a particular cell differ from those in adjacent cells, to avoid interference.
The foregoing is intended to be merely an abbreviated description of the known processes carried out in the GSM network.
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Figure 2 shows a conventional cordless handset system (such as a system operating according to the DECT or Digital European Cordless Telephone standard) in a building 30. Within the building 30, there is arranged a base unit 34 which is connected via a normal fixed telephone line 36 to the PSTN 25. The base unit 34 incorporates a radio transceiver and communicates by radio with a cordless handset 38. The base unit 34 and the cordless handset 38 thus together take the place of a normal fixed (wired) telephone handset. The cordless handset 38 can be normally parked on the base unit 34 for charging its battery power supply. Calls are made to the cordless handset 38 from other telephones in the PSTN by means of the fixed link 36 to the base unit 34 and thence by radio to the cordless handset itself. Similarly, calls made by the cordless handset are made by radio to the base unit 34 and thence to the PSTN (and may, of course, be transmitted by the PSTN to a mobile terminal in a mobile network such as illustrated in Figure 1). The radio range of the base unit 34 is restricted to the building 30 and its immediate surroundings. The base unit 34 operates at particular transmitting and receiving frequencies which are selected out of a fixed set of such frequencies and are normally selectable so as not to interfere with a similar cordless handset arrangement in an immediately neighbouring building.
It is clear that a cordless handset 38 of the type shown in Figure 2 cannot be used outside the radio range of the base unit 34. In particular, it cannot be used within the mobile network shown in Figure 1. Similarly, of course, a mobile terminal 16 shown in Figure 1 cannot be used as the cordless handset 38 of Figure 2. In each case, the frequencies and
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protocols with which the MTs and the cordless handset operate prevent such mutual operation (of course, handsets are known which are capable of operating on both GSM and DECT systems but these are in effect two handsets incorporated into one). It is possible, in general terms, for an MT, of the type shown in Figure 1, to be used within a building. However, although this is in principle possible, in practice coverage of a mobile telephone system within a building, particularly a large building, may be unsatisfactory because of radio propagation problems. Furthermore, users may be reluctant to use normal mobile telephone handsets within buildings where they could instead use terminals, such as the cordless handsets of the type shown in Figure 2, connected to the PSTN, because use of a handset within a PSTN is normally cheaper than use of an mobile telephone within a mobile network. On the other hand, an MT in a mobile network may be able to provide a greater range of services than a telephone handset within a PSTN.
Figure 3 shows a building 50, such as a home, having a service or processing unit 60 which is connected to an external network 62 via a broad or wide band connecting link 64 for the purpose of providing services within the home 50. A particular example of such services comprises television services, as indicated in Figure 3 at 66. Thus, the service unit 60 may be a set-top box providing such television services, and the link 64 may be via cable (such as a fibre optic cable) or radio link to the television network 62.
In principle, though, it should be understood that the service unit 60 is not necessarily provided for television purposes but may be any unit connected to a broad or wide band network 62 extending outside the home via a broad or wide band connecting link having
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download and upload capabilities. In accordance with a feature of the system being described, a base station 70 is associated with the service unit 60. This base station 70 is essentially equivalent to any of the BSs 14,15 shown in Figure 1-in other words, it is for carrying out the normal functions of a base station in a mobile telecommunications system. It thus provides coverage for a normal mobile terminal 16A (that is, a mobile terminal of the same type as the mobile terminal in Figure 1) within the home 50-in the same way as do the BSs in Figure 1 for MTs in the cells 18,20. The base station 70 in Figure 3 thus effectively converts the home and its immediate surroundings into a cell within the mobile telephone network. In principle, therefore, it is likely that the radio power of the base station 70 in Figure 3 will be less than that of the BSs in Figure 1.
By virtue of its association with the service unit 60, the base station 70 is connected, through the service unit 60, with the BSC and the MSC of the mobile telecommunications network (see Figure 1) via the broad or wide band connections 64 and the network 62. Because the broad or wide band link 64 provides an"always-on"two-way link between the MSC of the mobile network and the base station 70, the base station 70 operates in the same fashion as the other BSs in the mobile network. This enables the base station 70 to be operative within the home 50 even in cases where the home is physically located outside the area covered by the mobile telecommunications network or where coverage is poor or intermittent. The MSC will know the location of the mobile terminal 16A when it is within the home 50 and registered with the base station 70, just as it knows the location of the same mobile terminal if it is located in one of the normal cells 18,20 of the
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network and registered with the base station of that cell. Thus, calls can be directed to the mobile terminal 16A within the home 50 in the same way as they can be directed to mobile terminals within cells of the network shown in Figure 1.
When the mobile terminal 16A moves outside the home 50, it becomes de-registered from the base station 70 and then becomes registered with another base station in the cell of the network when it moves into the corresponding radio coverage area.
Although the operation of the mobile terminal 16A is essentially the same whether it is being used within the home 50 while it is registered with the base station 70 or while it is outside the home and registered with the base station of one of the normal cells of the network, the network will automatically know when the mobile terminal is being used within the home 50 because it will know that it is registered with the base station 70. It is therefore possible for the network to levy a different scale of charges for use of the mobile terminal within the home and/or to provide a different range of services.
Although the base station 70 in Figure 3 can simply be associated with the service unit 60 by being connected to it so as to receive signals from the MSC via the service unit and to transmit signals to the MSC via the service unit, the association could be more substantial. Thus the service unit and the base station could be physically associated by being placed within the same housing. More particularly, certain parts of the hardware and/or software of the service unit and the base station could be common to the two parts,
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thus enabling the overall cost and/or size to be reduced.
Although the foregoing description with reference to Figure 3 has referred to the use of a base station 70 for a mobile telecommunication system such as a GSM cellular network, other types of air interface could be used. Thus, the base station 70 could be a base station arranged for use in a Bluetooth system, the MT 16A now having Bluetooth-type transceiving capability. The MT16A need not, of course, be a mobile terminal.
The link in the building between the base station 70 and the MT 16A (or other transceiver) need not be a radio link but could be a different type of wireless link such as an infra-red link.