FI97598B - Radio system and subscriber radio station for a radio system - Google Patents

Description

97598

Radio system and subscriber radio station for radio system

The invention relates to a radio system comprising mobile subscriber radio stations and a fixed network divided into location areas formed by one or more base stations, wherein the base stations of different location areas use different location area information in signaling transmitted by radio.

10 Cordless telephone systems (CT), such as the CT2 digital cordless telephone system, have recently entered the market. Such a system typically comprises a base station, which is always based on joining an existing fixed telephone network. There are three main types of base stations: a home base station, a base station that can be connected to an office exchange or acting as an independent exchange, and the so-called telepoint base stations from which a CT telephone can only make outgoing calls.

20 Because current CT systems are thought of as PSTN telephone subscriptions, the call is routed to the CT terminal in the normal manner by dialing the telephone number of the PSTN numbering plan. In this case, the PSTN routes the call to the telephone exchange corresponding to that telephone number, to which the CT home base station is connected directly or via the CT office base station telephone exchange. The base station calls the CT terminal by radio with its identifier and the master:::: responds to make a call. Thus, in practice, a CT terminal can only be called through its home or office base stations (certain telephone subscriptions).

Patent applications FI-910211 and 920792 describe the connection of CT systems to mobile telephone networks. Mobile telephone networks do not have any addressable access points, such as PSTN telephone subscriptions, but only general purpose traffic channels used by mobile subscribers. In a cellular radio network, the subscriber device can move freely within the operating area of the network, in which case the network must know the location of the subscriber device so that the incoming call to the subscriber can be established. In current so-5 lock radio networks, the location update is based on automatic location update performed by the subscriber device itself as it moves within the network. When a call is established, the subscriber device is retrieved only from the area in which it last declared its presence. However, in the example CT system, no automatic location update performed by the subscriber device is defined, so the location of the subscriber device in the network cannot be ascertained. Valid location information is usually obtained during the last call. Thus, establishing an incoming call 15 to such a subscriber like a normal subscriber of a mobile network would often lead to a call set-up failure.

It is an object of the invention to alleviate the above problem.

This is achieved by a radio system of the type described in the first paragraph, which according to the invention is characterized in that

In an alternative third embodiment of the invention, the subscriber radio station responds to the paging identifier * · '* 25 by sending its own identifier sa to the fixed network base station each time it receives the first »\; t? once in a certain location area, but corresponds to the next •! : once in the same location area only when a predetermined time has elapsed since the first, last or N previous common call signs • · «30, where N is a positive *; * integer.

In the present invention, the fixed network initiates an update of the location of mobile radio stations in its area by sending from the base stations a common paging identifier for all subscriber radio stations in the calling area-35a. The mobile radio station responds to the shared paging identifier by sending its own identifier at the fixed network base station, for example in the same way as it responds only to a call containing its own unique identifier.

In the simplest embodiment of the invention, the system operates in such a way that the mobile radio station always sends a response to the received common call identifier. In this case, a randomly determined delay is preferably used between the receipt of the common call identifier and the transmission of the response, in order to prevent a large number of mobile radio stations from transmitting their response at the same time. However, such a simple solution significantly causes signaling on the radio path.

Therefore, in alternative embodiments of the invention, the mobile radio station responds to the received paging identifier only under certain conditions. When receiving a shared paging identifier for the first time in a particular location area, a mobile station responds as in a normal subscriber-specific paging, typically by responding with its own identifier to the fixed network. When receiving a shared call identifier a second or more times, a mobile station in the same location area responds only under certain conditions. If the conditions are not met, the mobile radio station. . does not react in any way towards the fixed network. Also in these embodiments, a random delay with which. avoiding the simultaneous response of multiple mobile radio stations to the call.

‘·’ ’The invention allows a fixed network to 30 dissa launches mobile radio stations to contact: ***; to the fixed network, wherein the network receives the identifiers of the mobile stations in question and is able, if it so wishes, to generate an internal location of the fixed network for the update procedure for the responders.

The present invention also relates to a subscriber radio station according to claim 6 of Patent 4,97598.

The invention will now be described in more detail by means of exemplary embodiments with reference to the accompanying drawing, in which Figure 1 schematically illustrates a cellular radio system in which the method according to the invention can be applied, Figure 2 shows a basic block diagram of a mobile radio station, and Figure 3 shows a basic block diagram of a base station.

In the following, the invention will be described using an example in which the digital cordless telephone system CT2 is connected as part of the digital mobile telephone system 15 GSM, which is the primary application of the invention. However, the method according to the invention can also be applied to other wireless telephone systems, such as DECT (Digital European Cordless Telecommunication) to GSM or its variants, such as DCS1800 and PCN (Personal Communication Network), or to other mobile telephone systems, such as NMT (Nordic Mobile Telephone). ).

The basic structure and basic functions of a GSM mobile telephone system are well known and appreciated by those skilled in the art; specified in the GSM system specification. Some basic concepts and elements of the GSM system will now be described with reference to Figure 1. GSM. the network includes at least one home location register (HLR), which is a database in which mobile phone information such as location ** information is always stored. The HLR is usually associated with an ::: 30 integrated or separate authentication center AC, which stores subscriber authentication information and algorithms. The system further includes a plurality of visitor registers (VLRs), each associated with one or more central areas. However, there is only 35 one VLR in each central area. The VLR is a database in which mobile phone information 5 97598 is stored for the time the mobile phone visits the VLR area. The VLR knows the location of the mobile phone MS with the accuracy of one location area. The HLR, in turn, knows in which VLR the mobile station MS is visiting and provides routing information to the travel network 5 for the terminating calls to the telephone MS. The HLR, in turn, receives the necessary routing information from the VLR. The HLR and VLR only have a signaling connection to other components of the mobile network.

The cordless telephone system CT2 or the like can be connected as a subsystem of such a GSM system. This is done, for example, by connecting the base stations BU of the CT2 system to the MSCs of the mobile switching centers. In Figure 1, the CT2 base stations BUI, BU2 and BU3 are connected to the MSCl and the CT2 base stations BU4 and BU5 to the exchange MSC2. In addition, a base station controller BUC of the CT2 system is connected to the exchange MSC2, which in practice can be, for example, a telephone exchange implemented on the CT2 principle, under the control of which the base stations BU5-BU6 are subordinated. The mobile switching centers MSC as well as the CT2 base stations BU and the controllers BUC are equipped with suitable additional hardware and software to perform the integration of the mobility functions of the systems and to adapt the number structures of the systems.

The GSM transmission network can in principle treat the CT2 subscriber in the same way as real GSM subscribers, 25 although at the radio data level at the latest, the CT2 and GSM systems are completely separate radio systems.

. GSM system and cordless telephone system • · «;;; such as CT2, integration and structural details

“·” Refers to patent applications FI 910211 and FI

. : V: 30 920792, which are incorporated herein by reference.

The signaling used on the radio path between the CT2 base station BU and the CT2 terminal MT is in accordance with the CT2 Common Air Interface (CAI) specification described, for example, in the article "CT2 Common Air Interface", M.W. 35 Evans, British Telecommunications Engineering, Vol. 9, 6 97598

July 1990, pages 103-111.

As stated earlier, in a cellular radio network, the subscriber device can move freely within the radio coverage area of the network, in which case the network must know the location of the subscriber device in order to establish an incoming call to the subscriber. In current cellular radio networks, such as GSM, location update is based on automatic location update performed by the subscriber device itself as it moves within the network. When a call is established, the subscriber unit is retrieved only from the area in which it has last indicated its presence.

The problem, however, is that in the CT2 system, for example, no automatic location update by the subscriber device has been defined, 15 so that the location of the subscriber device in the network cannot be ascertained. Valid registered location information is usually obtained during the last call. Thus, establishing an incoming call to such a subscriber, like a normal subscriber in a cellular network, would often result in a failure to establish call-20 because the subscriber cannot be found in the area indicated by the location information.

According to the invention, this problem is avoided by activating the location update operation performed by the subscriber device from the fixed network. To this end, • · 25 the fixed network transmits at appropriate intervals, e.g. 30 minutes, for all or all CT2 base stations BU. a caller ID that is different from the normal caller ID • · · ;;; so that it applies to all subscriber equipment MT in the calling area. Thus, the call identifier is not subscriber-::: 30 device-specific as in a normal call, in which case the call: ***: is answered only by that called subscriber device MT. The transmitted paging identifier further includes information defining the location area to which the base station belongs. In the context of the invention, the location area can be defined as a fixed number of CT2 base stations BU transmitting 7,97598 common or normal calls or otherwise information about the structure of the fixed network so that this transmitted network information fulfills the conditions for base stations BU to be considered as belonging to the same location area.

5 This location area information may be associated with a base station number, base station groups, organizer, operator, or other logical network entity. All that matters is that the interpretation of the location area is consistent in the subscriber unit MT and in the fixed network. In the CT2 system, this information may preferably be located in the LID (link identification code) transmitted by the base station, which is described in the above-mentioned article.

The subscriber equipment MT responds to the shared call identifier sent by the fixed network either absolutely always or under certain conditions, as will be explained later. The subscriber device MT may respond to the receipt of the shared paging identifier by acting as in a normal subscriber unit-specific paging, typically by responding with its own identifier to the fixed network, or as in a normal log-on process. For example, in a CT2 system, the subscriber device MT generally responds by sending its own PID (Portable identification code) and LID code to the base station BU, as described in the above article. Thus, in the call responses sent by the subscriber device MT to the fixed network base station 25 BU, the fixed network receives the identifiers of the subscriber devices and can, if desired, generate an internal network. for the MT of the devices of my subscriber who responded to the location update procedure call. In this case, the fixed network updates the location information of the base station BU through which the fixed network received the response and the identifier of the subscriber unit MT to the stored location information of the subscriber unit.

M t

For example, if the subscriber equipment MT and the base stations BU belong to a GSM mobile telephone system or a similar connected cordless telephone system, the VLR may be the fixed network element which also stores the location information of the cordless telephone subscribers and to which the location information of the subscriber equipment responding to the common call is transmitted.

As previously stated, the subscriber device MT may always or alternatively respond to the paging identifier 5 under certain conditions. In the former case, the subscriber device MT always performs, for example, a log-on procedure. In this case, it is advantageous to use a randomly determined log-on delay, thus avoiding the simultaneous response of many subscriber devices to the call.

In another embodiment of the invention, the subscriber device MT

responds to the co-identifier by sending its own identifier to the base station BU each time it first receives the co-identifier in a certain location area, but next time responds in the same location area 15 only after receiving N new co-identifiers, where N is a positive integer.

In yet another embodiment of the invention, the subscriber device MT responds to the paging identifier by sending its own identifier to the fixed network base station each time it first receives the paging identifier in a certain location area, but responds next time in the same location area only after a predetermined time from the first, last or N previous where N is a positive size-25 female number.

• i ·

The latter embodiments also have. it is advantageous to attach a random delay to the time of answering the call, thus avoiding multiple conditions. simultaneous response of the device MT to the call. It is also possible to specify a number that determines the number of retries of responses in a failed response case.

«· ·

In the above cases, the location area is not interpreted as changed when the location area information associated with the paging identifier has not changed or has changed in such a way that the conditions for the location area change have not been met. On the other hand, the location area is changed to 9 97598 when some pre-agreed parameter changes, e.g., 1) the base station changes, 2) the base station group changes, 3) the system changes, 4) the operator changes, and so on.

Figure 2 schematically illustrates a subscriber device MT in which the invention can be applied. The subscriber unit MT comprises a transceiver 21 connected to the antenna 27, wherein the receiver is connected via digital-to-analog converter and baseband circuits 23 to the speaker 10 and wherein the transmitter is connected to the microphone 26 via analog-to-digital converter and baseband circuits 24. The operation of the subscriber unit MT is controlled by microprocessor 22 , which processes the signaling transmitted and received by the transceiver 21. The invention can be implemented by modifying the software of the microprocessor 22 so that it also recognizes the common call identifier and responds to it as desired. The invention can thus be easily implemented, for example, in existing subscriber devices of the CT2 system with minor software changes.

Figure 3 shows a block diagram of a base station BU. The base station BU comprises a transceiver 31 connected to the antenna 35, which is connected via an interface unit 33 to, for example, an outgoing PCN link to the mobile switching center MSC. The operation of the base station BU is controlled by a microprocessor • · 25 ri 32, which takes care of the signaling transmitted and received by the transceiver 31 on the radio path. Correspondingly, the microprocessor 32 communicates via the interface 33 • · · II! with another fixed network, for example, forwarding the subscriber IDs it has received. The microprocessor 32 • «: .V 30 may further include a timer that provides for the transmission of the common * ##> J identifier at appropriate intervals.

The accompanying figures and the related description are intended to illustrate the present invention only. The details of the radio systems and subscriber radio stations according to the invention may vary within the scope and spirit of the appended claims.

Claims (6)

1. Radio systems comprising mobile subscriber radio stations (MS, MT) and a fixed network divided into traffic areas formed by one or more base stations (BS, BU), wherein different traffic area base stations use different traffic area information in radio signal transmitted, characterized of the fixed network transmitting at appropriate intervals from the base stations (BU) an all subscriber radio stations (MT) for the common call signal, the subscriber radio station (MT) responds to the common call signal by transmitting its own signal to the the fixed network base station (BU) always when it receives the common call signal for the first gang on a particular traffic area, but responds the following gang to the same traffic area only when a predetermined time has progressed from the first, last or N th preceding joint call. 20, where N is a positive integer, the fixed network updates in subscriber radio the position data of the station (MT) the traffic area of the base station through which the fixed network received the subscriber radio station's signal. . * J *. 25 2. A system according to claim 1, characterized in that the subscriber radio station (MT) responds to the common call signal after a randomly determined delay. ♦ The system according to claim 1 or 2, characterized in that the traffic area information refers to the base station number, base station group, system, operator or other logical system unit. System according to claim 1 or 2, characterized in that the subscriber radio station (MT) considers that the traffic area is changed where the base station, base station group, system or operator is changed according to the traffic area information. A subscriber radio station for a radio system comprising mobile subscriber radio stations (MS, MT) and a fixed network divided into one or more base stations 5 (BS, BU), where different traffic area base stations use different traffic area information on radio path sand signaling, characterized in that the subscriber radio station (MT) responds to a common call signal transmitted by the fixed network base station, which applies to all existing subscriber radio stations in the traffic area, by sending its own signal to the fixed network base station (BU) whenever it receives the common call signal for first time on a particular traffic area, but does not answer the next time on the same traffic area until a predetermined time has progressed from the first, last, or Nth preceding the common call signal, where N is a positive integer. Subscriber radio station according to claim 5, characterized in that the subscriber radio station 20 (MT) responds to the common call signal after a randomly determined delay. »·« «» * • «· • · · i« «• ·» t «· •« · »· • · * · · •« »·«