GB2396528A

GB2396528A - Transmitting current communication service availability in a control signal

Info

Publication number: GB2396528A
Application number: GB0229920A
Authority: GB
Inventors: David Sandberg
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2002-12-20
Filing date: 2002-12-20
Publication date: 2004-06-23
Anticipated expiration: 2022-12-20
Also published as: GB2396528B; GB0229920D0

Abstract

A communications terminal for use in a mobile communications system 1 includes means for generating and sending to one or more other terminals of the system, a control signal providing information about the terminal, wherein the terminal is operable to take part in a plurality of communication services and said information provided in the control signal includes data describing current availability of the terminal to take part in one or more of the communication services. The services may include: emergency telephone call, individual telephone call, interconnect or group telephone call, short data service or packet data service. The system terminals may include a mobile station 19, 20, a fixed terminal of the system, e.g. a control console and a fixed terminal of the system infrastructure, e.g. a base transceiver station 14. The control signal may comprise a labelling portion followed by a series of bits, each corresponding to one of the services and each indicating whether or not the service is currently available. The terminal may be operable in a trunked mode or direct mode, in a TETRA system.

Description

TITLB: MOBILE COMMUNICATIONS METHODS, SYSTEMS, PROCESSORS

AND TERMINALS

FIELD OF THE INVENTION

The present invention relates to mobile communications methods, systems and terminals.

BACKGROUND OF THE INVkNTION

Mobile radio communications systems, for example cellular telephony or mobile radio communications systems, typically provide for radio telecommunication links to be arranged between a plurality of subscriber or user 15 terminals, often referred to in the art as mobile stations (MSs). The term 'mobile station (MS)' generally includes both handportable and vehicular mounted radio units, radiotelephones and like radio communications units.

Mobile radio communications systems are distinguished 20 from fixed communications systems, such as the public switched telephone networks (PSTNs), principally in that mobile stations can move in geographical location to accompany their user and in doing so encounter varying radio propagation environments.

25 Mobile radio communications systems and mobile stations used in them may operate in one of two main modes, namely a TOO (bunked mode of operation) and a DMO (direct mode of operation). TMO communications use the fixed infrastructure supplied by the system operator, e.g. known 30 in some systems described further below as the SwMI (Switching and Manangement Infrastructure) including for

example base transceiver stations (BTSs), to deliver communications from one terminal, e.g. the MS of one user or operator, to that of one or more others terminals, e.g. the MS of one or more other users. In contrast, DMO is a 5 method that provides the capability of direct communication between two or more MSs without any associated operator's system infrastructure. Some MSs may be dual mode operating using either TMO or DMO as appropriate.

In a TMO radio communications system, each BTS has 10 associated with it a particular geographical coverage area (or cell). The cell defines a particular range over which the BTS can maintain acceptable communications with MSs operating within the cell. Often cells are combined to produce an expanded system coverage area. Furthermore, 15 cells are often grouped into location areas for the purposes of tracking a MS within the coverage area whilst minimising location-updating signalling.

In the field of this invention, mobile communications

systems are known which operate according to TETRA 20 (Terrestrial Trunked Radio) standards are known. TETRA standards are operating protocols which have been defined by the European Telecommunications Standards Institute (ETSI). The present invention is useful in (but not exclusively in) TETRA systems, i.e. systems operating 25 according to TETRA standards. Such systems are designed for use for example by organizations, particularly safety and emergency services such as the police, ambulance and fire services. Currently available TETRA systems operate in either 30 TMO or DMO to send a communication from a transmitting MS to one or more receiving MSs.

In multi-service systems such as TETRA systems the handling of interactions between services is becoming complicated. It is necessary for the infrastructure in a bunked system to know the availability of a mobile station 5 to provide a particular service, i.e. take part in a particular form of communication. However, in currently available systems there is no simple way of the infrastructure clearly knowing such availability. In some cases the infrastructure may deduce that a certain service 10 is available but such a deduction may be incorrect.

For example, a registration of the location of a MS by a TETRA network infrastructure is also an implicit registration of some call services, such as individual call, group call and short data services (SDS). However, 15 these services may in fact not be available because the MS is taking part in an emergency call which temporarily disables other services.

Another example is found in TETRA systems, where members of a group are to take part in a group call. These 20 members are attached to the network individually. However, there is no guarantee that a particular MS of the group which has attached to the network is currently available to receive a group call signal and thereby take part in the group call.

25 A further example is where a packet data registration is made when establishing a PPP (point to point protocol) connection to a computer. However, the MS may not be ready to receive packet data.

SO - L&RY OF THE PRESENT INVENTION

According to the present invention in a first aspect there is provided a communications terminal for use in a 5 mobile communications system including means for generating and sending to one or more other terminals of the system a control signal providing information about the terminal, wherein the terminal is operable to take part in a plurality of communication services and said information 10 provided in the control signal includes data describing the current availability of the terminal to take part in one or more of the communication services.

Examples of the services are emergency call, individual call, interconnect or group call, short data 15 service, packet data service or other service commonly used or known for use. The said control signal may comprise a portion having a series of bits corresponding to the services to be denoted. Each bit may indicate whether or not the service it denotes is currently available. The 20 portion may be preceded by one or more labelling bits indicating to the receiving terminal the data represented by the following bits. The control signal may be included in system control signalling which is conventionally transmitted according to a standard communications 25 protocol, e.g. in a dedicated frame or part of a frame set aside in a multi-frame TDMA (time division multiple access) procedure. The said terminal may be a terminal to be used by an operator or user, e.g. either a mobile station or a fixed 30 terminal, e. g. a control console, of a mobile communications system. Communications in the mobile

communications system may be wireless, e.g. radio, communications. The said means may include a controller, which may in practice comprise one or more suitably programmed 5 microprocessors, which initiates and processes data to be sent as wireless signals to another terminal and a wireless transmitter for converting the data into a wireless transmissible form. In practice, the function of the transmitter and also that of a corresponding receiver may 10 be combined in a single transceiver unit.

The receiver terminal may be a fixed terminal included in the infrastructure of a mobile communication network.

For example, the receiver terminal may comprise a base transceiver station. The information received may be 15 processed in a processor and stored in a memory associated with the receiver terminal. The information may be used to control selectively the sending of signals to the first mentioned terminal according to whether the first mentioned terminal is able to receive the signal in its current 20 service state.

The receiver terminal may alternatively comprise a mobile terminal with which the mobile station is communicating directly in DMO.

According to the present invention in a second aspect 25 there is provided a system for mobile communication including a first terminal and a second terminal at feat one of which is a mobile station, wherein the first terminal is operable to generate and send to the second terminal and optionally to one or more other terminals of 30 the system a control signal providing information about the first terminal, wherein the first terminal is operable to take part in a plurality of communication services and said

information provided in the control signal includes data describing the current availability of the first terminal to take part in one or more of the communication services.

According to the present invention in a third aspect 5 there is provided a method of operation in a system for mobile communication including a first terminal and a second terminal at least one of which is a mobile station, wherein the first terminal generates and sends to the second terminal and optionally to one or more other 10 terminals of the system a control signal providing information about the first terminal, wherein the first terminal is operable to take part in a plurality of communication services and said information provided in the control signal includes data describing the current 15 availability of the first terminal to take part in one or more of the communication services.

The terminal, system and method according to the present invention may be operable according to standard TETRA procedures.

20 The invention beneficially allows the receiving terminal to have immediate information about the services currently available in the terminal which sent the signal which the receiving terminal can store. This allows more rapid processing of signals by the receiving terminal or 25 one or more processors associated therewith, e.g. in a network infrastructure or another mobile or fixed terminal.

Advantageously, this allows quicker communication set-up in the communication system compared with the prior art and

avoids attempted setting up of a communication which cannot 30 be completed because a target terminal is currently unable to take the communication.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: 5 BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is a block schematic diagram of a mobile communication system.

FIG. 2 is a block schematic diagram of a mobile 10 station used in the system shown in FIG. 1 FIG. 3 is an illustration of the content of a control data signal sent by a mobile station of the kind shown in FIG.2.

15 DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring to FIG. 1, there is shown schematically a mobile radio communication system 1 operating in accordance with TETRA standard protocols. The system 1 comprises a 20 SwMI 10 and a plurality of MSs, two of which, MSs 19 and 20, are shown. The MSs 19, 20 in the system 1 can communicate directly with the SwMI 10 and with each other via the SwMI 10 in a TMO. The MSs 19, 20 can also communicate directly with each other in a DMO.

25 Communications in the TMO are sent to and received from the MSs 19,20 by a BTS 14 and the control of such communications is by a processor 16. The BTS 14 and the processor 16 are sub-systems within the SwMI 10.

Communications from the MSs 19 or 20 can also be sent via 30 the BTS 14 to a MSC (master switch controller) 15 also incorporated in the SwMI 10. The MSC 15 is linked by a

direct link (call control connection) 17 to a PSTN (public service telephone network) 12.

The BTS 14 routes calls to the processor 16 or to the MSC 15 depending on whether the call is directed to another 5 MS in the system 1 or to a target terminal (not shown) to be reached via the PSTN 12. The SwMI 10 incorporates a MS register 18 operably coupled to the processor 16. The register 18 maintains records of information about the MSs in the system 1. In particular, the register 18 maintains a 10 record of the identity and location of the MSs. The identity is determined for example by the MS fixed ID address number which can initially be used to contact each MS by the SwMI. For a TETRA terminal, this is the so called ITSI (individual TETRA subscriber identity). The register 15 18 may be associated with a visited location register forming part of the processor 16 which gathers information relating to the location of the current cell or system which can serve the MS in question. Thus, in the embodiment shown in Figure 1, the visited location register is aware 20 that the MS 20 is currently being served by the SwMI 10.

The location information may be provided to the visited location register of the processor 16 in a known manner.

Referring now to FIG. 3, a block diagram of the MS 19 adapted to operate using an embodiment of the present 25 invention is shown. The MS 19 may be suitable for operating in a TMO or DMO depending on the mode selected. Operation of functions within the MS 19 are controlled by a controller 30, which generally comprises a suitably programmed digital signal processor. The controller 30 may 30 also controls the information flow and operational state of processors within the MS 19.

Information relevant to operation of the MS 19 is stored in a memory 34 associated with the controller 30.

For example, layer 2 ID address information to be used in communications sent by the MS 19 is stored in the memory 5 34. The MS 19 has a receiver chain and a transmitter chain and includes an antenna 42 coupled to a duplex filter or circulator 44 that provides isolation between receiver and transmitter chains within the MS 19. The receiver chain 10 includes a receiver front-end circuit 46 (effectively providing reception, filtering and intermediate or base-

band frequency conversion of incoming communications). The front-end circuit 46 receives radio communications from another terminal, such as another MS, e.g. the MS 20 (FIG.

15 1). The front-end circuit 46 is serially coupled to a signal processor (generally realised by a digital signal processor, DSP) 48a coupled to the controller 30. The signal processor 48a performs signal demodulation, error correction and formatting, and recovers end-to-end 20 encrypted information from the received signal.

A signal representing the information recovered by the signal processor 48a is serially coupled to a baseband processing device 50a, which takes the information received from the processor 48a and formats it in a suitable manner 25 to send to an output device 51, such as a speaker and/or display, e.g. a visual display unit (VDU).

The functions of the controller 30, the signal processor 48a and the baseband processor 50a although shown as separate in FIG. 2 may be implemented within the same 30 physical microprocessor device.

The transmitter chain of the MS 19 essentially includes an input device 60, such as a microphone, coupled

in series through a baseband processor sob, a signal processor 48b, transmitter/modulation circuitry 62 and a power amplifier 64. The processor 48b, transmitter/modulation circuitry 62 and the power amplifier 5 64 are operationally responsive to the controller 30. An output from the power amplifier 64 is supplied to the duplex filter or circulator 44, as known in the art. The transmit chain in the MS 19 takes the baseband signal from input device 60 and delivers it to the signal processor 48b 10 where it is encoded for transmission by the transmit/modulation circuitry 62 and power amplifier 64.

The signal processor 48b in the transmit chain may be implemented in a device distinct from the processor 48a in the receiver chain. Alternatively, a single processor 48 15 may be used to implement processing of both transmit and receive signals, as shown in FIG. 2. Similarly, the baseband processor 50a and the baseband processor 50b may be separate devices or may be combined in a single device 50 as shown in FIG. 2.

20 Of course, the various components within the MS 19 can be realised in discrete or integrated component form, with an ultimate structure therefore being a suitable design selection from these forms.

In use of the MS 19, control signals are sent by the 25 MS 19 to the SwMI 10 (FIG. l) to provide information to the SwMI 10 about the MS 19. These control signals, sent in accordance with TETRA standard protocols, are included in control signal frames of the signalling timing structure as specified in the protocols. These signals include amongst 30 other things, the identity of the MS l9, its operational state (i.e. in active or sleep mode) and the BTS to which it is currently attached. In accordance with an embodiment

11 i,, J. _ of the invention, the control signals also include a data block informing the SwMI 10 of the availability of the MS 19 to provide certain services. An example of such a data block is shown in FIG. 3. The data block, indicated by 5 reference numeral 70, includes a label portion 71 which is a code typically several bits long and understood by the receiving terminal, i.e. SwMI 10, indicating the type of data which is to follow. The data block also includes six consecutive bits 71 to 77. Each bit represents the current 10 availability of the MS 19 to take part in a particular service. For example, if the MS 19 is currently in an emergency call, indicated by bit 71, other services are disabled. So bit 71 is a '1' whereas bits 72 to 77 are '0'.

When the MS is able to take part in all of the possible 15 services, all bits 71 to 77 are '1'. The data to be included in the block 70 is generated by the controller 30 using information supplied thereto in a known manner from the various internal sources within the MS 19. The block 70 is updated every time a control signal block of data is 20 generated and sent by the MS 19 to the SwMI 10. The SWMI therefore maintains an awareness of the service availability states of the MS 19 and stores and updates this information in a memory associated with the processor 16. 25 In an alternative mode of use, the MS 19 may communicate in DMO mode with the MS 20. The data block 71 is again produced and sent in control signalling to the MS 20 and the MS 20 recognizes, stores and updates the data in its own known processor and memory.

Claims

1. A communications terminal for use in a mobile 5 communications system including means for generating and sending to one or more other terminals of the system a control signal providing information about the terminal, wherein the terminal is operable to take part in a plurality of communication services and said information 10 provided in the control signal includes data describing the current availability of the terminal to take part in one or more of the communication services.

2. A communications terminal according to claim l and wherein the services in which the terminal is capable of 15 taking part include emergency telephone call, individual telephone call, interconnect or group telephone call, short data service and packet data service.

3. A communications terminal according to claim l or claim 2 and wherein said control signal comprises a portion 20 having a series of bits corresponding to the services to be denoted, each bit indicating whether or not the service it denotes is currently available.

4. A communications terminal according to claim 3 and wherein said portion is preceded by a labelling portion 25 indicating to the receiving terminal the data represented by the following bits.

5. A communications terminal according to claim 3 or claim 4 and wherein said the control signal is included in system control signalling which is transmitted according to 30 a standard communications protocol in a dedicated frame or part of a frame set aside for such signalling.

6. A communications terminal according to any one of the preceding claims and wherein said terminal is a mobile station wherein communications are by wireless.

7. A communications terminal according to claim 1 or 5 claim 2 and wherein said terminal is a fixed terminal wherein communications are by wireless.

8. A communications terminal according to any one of the preceding claims and wherein said means includes a controller which initiates and processes data to be sent as 10 wireless signals to another terminal and a wireless transmitter for converting the data into a wireless transmissible form.

9. A communications terminal according to any one of the preceding claims and wherein the terminal is operable 15 according to standard TETRA procedures 10. A system for mobile communication including a first terminal and a second terminal at least one of which is a mobile station, wherein the first terminal is operable to generate and send to the second terminal and optionally to 20 one or more other terminals of the system a control signal providing information about the first terminal, wherein the first terminal is operable to take part in a plurality of communication services and said information provided in the control signal includes data describing the current 25 availability of the first terminal to take part in one or more of the communication services.

11. A system according to claim 9 and wherein the second terminal is operable to store information included in the received control signal about the availability of the first 30 terminal to take part in communication services and to use the information in selecting what communications are to be sent to the first terminal.

12. A system according to claim 10 or claim 11 and wherein the system is operable according to standard TETRA procedures. 13. A method of operation in a system for mobile 5 communication including a first terminal and a second terminal at least one of which is a mobile station, wherein the first terminal generates and sends to the second terminal and optionally to one or more other terminals of the system a control signal providing information about the 10 first terminal, wherein the first terminal is operable to take part in a plurality of communication services and said information provided in the control signal includes data describing the current availability of the first terminal to take part in one or more of the communication services.

15 14. A method according to claim 11 and wherein the second terminal stores information included in the received control signal from the first terminal about the availability of the first terminal to take part in communication services and uses the information in 20 selecting what communications are to be sent to the first terminal. 15. A method according to claim 13 or claim 14 and wherein the system is operable according to standard TETRA procedures. 25 16. A terminal according to claim 1 and substantially as herein described with reference to the accompanying drawings. 17. A system according to claim 10 and substantially as herein described with reference to the accompanying 30 drawings.

18. A method according to claim 13 and substantially as herein described with reference to the accompanying drawings.