EP0578801A1 - Systeme de radiocommunication mobile prive interconnecte - Google Patents

Systeme de radiocommunication mobile prive interconnecte

Info

Publication number
EP0578801A1
EP0578801A1 EP19930903242 EP93903242A EP0578801A1 EP 0578801 A1 EP0578801 A1 EP 0578801A1 EP 19930903242 EP19930903242 EP 19930903242 EP 93903242 A EP93903242 A EP 93903242A EP 0578801 A1 EP0578801 A1 EP 0578801A1
Authority
EP
European Patent Office
Prior art keywords
channel
communication
mobile radio
base station
channels
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19930903242
Other languages
German (de)
English (en)
Inventor
John Hollis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Electronics Ltd
Original Assignee
GEC Marconi Ltd
Marconi Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GEC Marconi Ltd, Marconi Co Ltd filed Critical GEC Marconi Ltd
Publication of EP0578801A1 publication Critical patent/EP0578801A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/08—Trunked mobile radio systems

Definitions

  • PMR private mobile radio
  • PMR systems such as those used by Military and Law Enforcement Agencies.
  • PMR systems are known and generally comprise a base station and a plurality of mobile terminals.
  • Each base station serves a particular area and can communicate with mobile terminals within its area and with other similar base stations serving respective areas through switching centers.
  • the mobile terminals can communicate with each other via the respective base stations or directly.
  • Narrow band channels enable more efficient utilisation but it has been recognised that significant advantages are obtained by "trunking” i.e. where traffic communication channels are only allocated and used whilst a call is in progress. This is similar to a telephone communication system.
  • DTI document MPT 1318 describes such advantages and indicates that the carrying capacity of a channel within a "trunked” group greater than 10 can approach 0.9E (erlang) .
  • the "erlang” is a measure of channel loading (see MPT 1318 pages ' 16-19) .
  • a trunking technique requires the mobile radio terminals to relax to a control channel over which channel call control messages are passed. In this way, a mobile radio terminal may be directed to a particular communication channel when a call is made. Similarly, when a call is terminated, the radio terminal releases the communication channel and relaxes to the control channel. The same communication channel is then available to other users.
  • the technique of call control is similar to that of telephony and inevitably has a delay which may be of the order of 500m sees. This, coupled with a probability of a delay in acquiring a radio channel if all resources are actually in use, is causing concern as, without discipline, speech or word clipping may result.
  • the problem of the 'Don't Shoot' command becoming 'Shoot' is one aspect of such a problem.
  • this problem is largely avoided by the communications being undertaken over an Open', all available, channel. There is therefore no call set up delay and, as all units are permanently tuned to the channel, there is a comfort to everyone in that all communications are received.
  • Requirements (a) and (b) are supported by the MPT 1327 systems described above and are established by similar - - system call control techniques i.e. Mobile/Radio units are normally tuned to a control channel over which call control is exercised. If it is established that both units to be involved in a one to one call are available, both are instructed to re-tune to a traffic channel. Should both radios be within the coverage of, a single Base Station, then both would utilise a common traffic channel. However, where two base stations are used, different R.F. traffic channels may be used and switch connected by the system infrastructure.
  • the establishment of a group call is similar to a 'private' call except that a call control message is broadcast to a pre-defined group of mobile radios terminals to re-tune to a particular traffic channel. Again this arrangement could encompass multiple R.F. base stations which would be conferenced to form a wide-area, group connection.
  • the difficulty of words being missed because of call set up delays can be overcome by introducing a speech delay in the radio equipment.
  • the speech delay would then enable a group call to be established on, for example, receipt of a 'Press to Talk' command whereby to minimise the risk of missed instructions.
  • the use of digitised speech would simplify such realisations as, with 8kb/sec traffic, relatively small digital delay lines (shift registers) could be used.
  • the delay could, by processor control, be dynamically controlled to adapt to various call set up times and after the first speech interchange be effectively switched out by detection of a "non-speech" interval.
  • the open channel facility would avoid all such difficulties and would be provided by pre-allocating a channel (or channels on conference connected base stations) to form an open group. Pre-defined groups of mobile terminals would then automatically be instructed via the call control channel to re-tune to the pre-allocated channel(s). All mobile radio terminals would then be openly conferenced.
  • new arrivals i.e. radios that have just been switched on
  • new arrivals i.e. radios that have just been switched on
  • the arrangement is not of course restricted to organising a single open group as by pre-allocating several channels a number of independent groups can be established and mobiles/radios having specific ranges of addresses etc directed to the appropriate group call conference. Similarly different open channel groups can be established and cleared as necessary.
  • the formation of the open channels will be effected, in general, by commanding mobile terminals having particular address ranges. Each mobile terminal however would have a unique identity within the group range. Therefore by employing command signalling over the traffic channel allocated to the group (MPT 1327 signalling enables this) individual mobile terminals can be instructed to re-tune to another channel for a one-to-one call, to be temporarily part of a dynamically established group call or to be a member of another open channel.
  • MPT 1327 signalling enables this
  • individual mobile terminals can be instructed to re-tune to another channel for a one-to-one call, to be temporarily part of a dynamically established group call or to be a member of another open channel.
  • Figure 1 is a schematic diagram of a private mobile radio system in accordance with the present invention.
  • Figure 2 is a diagram indicating the additional features of such a system incorporating "Open Channel” communication.
  • a private mobile radio system comprises a first base station 10 arranged for broadcast communication over a first area 12 to a plurality of mobile radio terminals 14 located within such area.
  • An adjacent area 16 is served by a base station 18 and broadcasts to mobile terminals 14 within the adjacent area.
  • a plurality of such areas adjacent, contiguous or overlapping may be provided and a switching centre 20 serves to connect the various base stations to each other and to other networks.
  • the system has allocated thereto a plurality of narrow band radio channels, for example, 100 and these, in turn, are allocated to the base stations 10, 18 etc in accordance with the traffic demand in the respective areas 12, 16 etc and in accordance with minimum radio interference in adjacent areas.
  • the allocated channels comprise, for each area, at least one call control channel and one or more communication channels for carrying communication traffic.
  • a one-to-one call by one mobile radio terminal 14 to another mobile radio terminal 14 whether in the same or a different area is initiated and made in accordance with the protocols described in MPT 1327.
  • the mobile terminal 14 firstly hunts for the strongest control channel system and makes a request on this frequency. When the base station acknowledges, the mobile indicates the address of a terminal to be called. The base station then determines the availability of the called mobile terminal. If the called terminal is available, the base station sends to the calling mobile terminal a go-to-traffic-channel signal. A similar signal is sent to the called mobile terminal by the base station if it is in the same area or via the switching centre and the appropriate base station if it is in a different area. The one-to-one communication is then established.
  • a group or conference call is made from a mobile terminal 14 to a plurality of other mobile terminals in the same or different areas as described in MPT 1327.
  • the initiation is the same as before.
  • the base station then ascertains the availability of a traffic channel and advises the calling terminal to go to this channel and all the called terminals (either directly or through the switching centre and the respective base stations) to go to the allocated traffic channel (or channels) .
  • the open channel will be established in similar manner to that of an MPT 1327 group call.
  • a System Manager or Controller 22 provided at a switching centre 20 or at a base station, would define the range of mobile radio terminal 14 addresses to form the group and would define the duration of the group call.
  • the Controller 22 would instigate the call and initiate its clear down.
  • the system would also be organised periodically to broadcast the 'group call' instruction on the control channel to catch late comers and to allow for personnel shift changes on instances of long duration communication requirements.
  • Mobility of radios is catered for to ensure use of Base Stations covering specific locations.
  • the 'useability' of a particular base station is established by assessment of the control channel. With open channel operation this, of course, is not practical. Assessment of the received traffic channel radio signal strength is therefore undertaken at the mobile radio terminal 14. If then the level is too low, the terminal or terminals would relax to the control channel and proceed to hunt for another useable one. Upon acquisition and registration with a different base station, the mobile terminal 14 would then be instructed to rejoin the open channel group by the periodic control channel message.
  • the call control is full-duplex (as far as the base station is concerned) and is transparent to a user of a mobile radio terminal.
  • the transmission by the base stations are in frames each divided into a plurality of slots.
  • the duration of each frame is an integral number of time slots but such number may increase or decrease depending on traffic demand.
  • the frame size accordingly varies.
  • the communication channels (of which only four are shown) are half duplex.
  • the system controller 22 initiates the Open Channel by reserving at least one communication channel and instructing the assigned group of mobile terminals 14 via the call control channel to tune to the reserved channel. Thereafter, communication by the controller 22 with a particular mobile terminal within the group may be made by digital instructions on the reserved channel. Such "flash" instructions are unlikely to disturb normal communication on the reserved "open channel” and may be of such brief duration as to pass unnoticed.
  • the controller 22 may wish so to communicate with an individual mobile terminal 14 to instruct the terminal to participate in a one-to-one or a group call on another channel.
  • trunked mobile radio communication system including an "open channel facility by Military and Law Enforcement Groups may require levels of system security not normally required of civil use systems. Problems of speech secrecy, jamming and low probability of communication detection may therefore have to be resolved.
  • the MPT 1327 trunking system is organised via a control channel, and jamming of this could therefore effectively disable the system.
  • a state could generally be detected by both mobile terminals and fixed infrastructure by virtue of continuous receipt of non MPT messages.
  • the system could then establish a new control channel and rely upon the mobile terminals 'finding' it via normal channel hunt protocols.
  • Elaborate forms of jamming may of course be realised such that MPT messages are generated whilst holding out any access by mobile terminals. This would have to be avoided by continually changing the control channel frequency and avoiding any that are identified as potentially jammed. Frequency change of the control channel frequency would result in mobile terminals being 'out of service' whilst they sought the latest control channel.
  • Jamming could of course be directed at specific channels and probably the strategically important "Open Channel'. Making these frequency agile would minimise this and can be achieved by specific 'Move' or 'Go To Channel' commands broadcast in encrypted form over the currently used channels. Mobiles that fail to follow such commands would be organised to hunt for the call control channel and then be redirected to the open channel frequency in use. ⁇ ) Low Probability of Detection

Abstract

Système de radiocommunication mobile privé interconnecté assurant des communications à canaux ouverts à la demande entre plusieurs terminaux de radiocommunications mobiles désignés appartenant au système.
EP19930903242 1992-02-05 1993-02-04 Systeme de radiocommunication mobile prive interconnecte Withdrawn EP0578801A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9202461 1992-02-05
GB9202461A GB2264210A (en) 1992-02-05 1992-02-05 Private mobile radio system

Publications (1)

Publication Number Publication Date
EP0578801A1 true EP0578801A1 (fr) 1994-01-19

Family

ID=10709888

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930903242 Withdrawn EP0578801A1 (fr) 1992-02-05 1993-02-04 Systeme de radiocommunication mobile prive interconnecte

Country Status (6)

Country Link
EP (1) EP0578801A1 (fr)
JP (1) JPH06506815A (fr)
AU (1) AU3458793A (fr)
CA (1) CA2106876A1 (fr)
GB (1) GB2264210A (fr)
WO (1) WO1993016566A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI98686C (fi) * 1993-11-01 1998-07-22 Nokia Telecommunications Oy Menetelmä suorakanavalla liikennöivän tilaaja-aseman hallitsemiseksi radiojärjestelmässä ja radiojärjestelmä
FI96155C (fi) * 1994-03-24 1996-05-10 Nokia Telecommunications Oy Menetelmä ympäristökuuntelun toteuttamiseksi ja radioyksikkö
FI100499B (fi) * 1994-12-28 1997-12-15 Nokia Telecommunications Oy Ryhmäpuhelun ylläpitäminen matkaviestinjärjestelmässä
FI98579B (fi) * 1995-01-20 1997-03-27 Nokia Telecommunications Oy Suorakanavalla liikennöiminen
FI950745A (fi) * 1995-02-17 1996-08-18 Nokia Telecommunications Oy Matkaviestimien poimiminen suorakanavalta
FR2805104B1 (fr) * 2000-02-10 2003-07-04 Vesta Finance Systeme de radiocommunication public
CN100446593C (zh) * 2005-07-04 2008-12-24 大唐移动通信设备有限公司 一种集群通信系统
US8730871B2 (en) 2009-05-22 2014-05-20 Raytheon Company System and method for providing voice communications over a multi-level secure network

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4723264A (en) * 1987-06-19 1988-02-02 Motorola, Inc. Signalling method for establishing trunked communication
US5025254A (en) * 1989-06-23 1991-06-18 Motorola, Inc. Communication system with improved resource assignment

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9316566A1 *

Also Published As

Publication number Publication date
CA2106876A1 (fr) 1993-08-06
GB9202461D0 (en) 1992-07-22
AU3458793A (en) 1993-09-03
WO1993016566A1 (fr) 1993-08-19
GB2264210A (en) 1993-08-18
JPH06506815A (ja) 1994-07-28

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