NZ233829A - Intercommunication between cell phone systems - Google Patents

Description

O y:. 23 3 8 2 Cli, . o : -v. ;>«■" AS-l-'O £ 5 SEP 1992 Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATldN— J COMMUNICATION SYSTEM TO COMMUNICATION SYSTEM COMMUNICATION SYSTEM W WE, MOTOROLA, INC., a corporation of the State of Delaware, U.S.A. of 1303 East Alogonquin Road, Schaumburg, Illinois 60196, U.S.A. hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: (followed by page la) #* ;•J '1 'J ')' J ;— • > V J ;10 ;This invention relates generally to communication systems, and more particularly to interlinked trunked communication systems. ;15 ;Trunked communication systems are known in the art. In generai such systems include a resource controller 20 (which may be centrally located or distributed) that manages communications between communication units (such as fixed location, mobile, and portable two-way radios) on a plurality of communication resources (such as frequency pairs or TDM time slots) that are supported by a 25 plurality of corresponding repeaters. ;A number of such systems are available, including the Smartnet and Privacy Plus systems from Motorola, the Clearchannel LTR system from E.F. Johnson, and the Sixteen Plus and Sweet Sixteen systems from General Electric. ;2 ;CM-00520H ;In general, such systems tend to operate independent of one another. Therefore, a communication unit located in a first system will generally not be able to communicate with a second communication unit located in a second 5 communication system. ;Some prior art systems interlink one or more communication systems through use of an appropriate dedicated landline. So configured, communication units in different communication systems may be able to 10 communicate with one another. Such an approach, however, poses several disadvantages, including increased cost and relative inflexibility. In addition, even when so linked. ;such solutions do not readily accommodate group calls. ;It is an object of the invention to provide a system and method of economically and flexibly interlinking two or more communication systems, or to at least provide the public with a useful choice. ;According to one aspect of the invention there is provided a communication system that supports communications amongst a plurality of member communication units, the communication system having: ;allocatable amongst the member communication units, wherein at least one of the communication resources supports a first set of communication resources that are ;-2b- ;primary control signalling for use by the member communication units to facilitate allocation of the communication resources amongst the member communication units; and a resource controller for allocating the communication resources amongst the member communication units and for sourcing, at least in part, the primary control signalling; wherein: ;A) the at least one of the communication resources also supports secondary control signalling for use by a least one other communication system to facilitate system-to-system communications; ;B) the resource controller sources, at least in part, the secondary control signalling; and ;C) the primary control signalling and secondary control signalling are not directly compatible. ;This ;' system functions in conjunction with at least two communication systems that each include a set of communication resources and resource controllers for controlling allocation of these resources. Pursuant to various embodiments of this invention, one or more ot these communication systems are also provided with one or more supplemental receivers that are at least substantially compatible with the communication resources that are ordinarily used in the opposing system. So configured. ;(followed by page 3) ;4 0 ;t J ;3 CM-00520H ;communication requests sourced from a first system can be received by the a second system having such a supplemental receiver tuned to the appropriate resources of the first system, and thereafter be properly processed. ;5 In one embodiment, each communication system is provided with a receiver that is compatible with the control communication resource, such as a dedicated control channel, of an opposing system. So configured, communications sourced from one system can be received 10 by the other system anc properly processed. ;In another embodiment, a receiver can be provided to accommodate each communication resource supported by the other communication system. This embodiment offers a high degree of flexibility in communication resource 15 allocation. ;In another embodiment, the control communication resource supports both primary control signalling used by member communication units of the communications system to facilitate allocation of the communication 20 resources amongst the member communication units. In addition, this control communication resource also supports secondary control signalling that is intended for and used by a second communication system to facilitate system to system communications. ;25 In yet another embodiment, the primary control signalling and the secondary control signalling can be transmitted at different data rates, wherein the secondary control signalling is transmitted at a higher data rate, in yet another embodiment, communication units that 30 belong to a common fleet or group share, at least in part, a ;■ 13 1932 ;-V'v ;CM-00520H ;common group ID in each system. For example, a first ID is used while communicating within the home system. The home system recognizes this ID as representing a local group or fleet. A second ID can also be used by the radios 5 that comprise the group or fleet when in a second system. This second ID is preregistered in the second system as a roaming ID, along with information regarding the home system that corresponds to that particular ID. In a similar manner, additional IDs can be used with different systems 10 for which the radios are preregistered as roamers. ;When such a non-home system determines that a preregistered roamer has entered its system, the non-home system will use its supplemental receiver to monitor the communication resources of the home system for that 15 roamer. Communications from the home system that are intended for the roamer can then be intercepted and forwarded on to the roamer through use of the non-home system resources. ;20 ihe invention will be described by way of example with reference to the accompanying drawings in which: ;Fig. 1 comprises a block diagram depiction of a first embodiment of the invention; ;Fig. 2 comprises a timing diagram of the control 25 communication resource in accordance with the first embodiment; ;Fig. 3 comprises a block diagram depiction of a second embodiment of the invention; and ;Fig. 4 comprises a block diagram depiction of a third 30 embodiment of the invention. ;13 A US 1392 ;5 ;CM-00520H ;Referring to Fig. 1, a first embodiment can be seen as depicted generally by the numeral 100. The system (100) 5 operates in conjunction with other communication systems. For purposes of this description, only two such communication systems (101 and 102) will be described. ;The first communication system (101) includes a resource controller (103) that functions to control 10 allocation of a first set of communication resources. In this embodiment, it will be presumed that the communication resources are supported by a plurality of repeaters (104), and that the communication resources themselves comprise a first set of three frequency pairs A-15 C. In addition, for purposes of this description, it will be presumed that one of the repeaters (104) supports system control information related to resource allocation requests and grants. Such system control information intended for member communication units (106) of that system (101) is 20 referred to herein as primary signalling information. The resource controller (103) controls the repeaters (10-4) and interchanges resource allocation request and grant information as primary control signalling through the repeaters (104) via an appropriate link (107) as well 25 understood in the art. ;A second communication system (102) similarly includes a resource controller (108), repeaters (109) (that support communication resources D-F), and an appropriate link (111) therebetween. In this embodiment, the 30 communication resources A-C of the first system (101) are ;233829 ;6 CM-00520H ;different from the communication resources D-F of the second system (102). Therefore, the two systems (101 and 102) are not able to communicate directly with one another through the repeaters provided. ;5 Pursuant to this invention, each system (101 and 102) ;is also provided with a receiver (112 and 113) that is capable of compatibly receiving at least one communication resource of the other system. In this embodiment, the communication resource so received is the control 10 communication resource. Received signalling information is then coupled from the receiver (112 and 113) to the associated resource controller (103 and 108, respectively) via an appropriate link (114 and 115, respectively). ;So configured, the resource controller (103 and 108) 15 are capable of monitoring the control communication resource of the other system. ;With reference to Fig. 2. the signalling as supported by the control communication resource of each system (101 and 102) will be described. The outbound primary control 20 signalling uses a slotted Aloha channel access protocol. Typically, outbound primary control signalling words (PCS) (201) are sourced by the resource controller and transmitted by the appropriate control communication resource repeater. These PCS (201) data transmissions are 25 interleaved with appropriate synchronization words (202). Further, a system ID (203) is occasionally transmitted, all as well understood in the art. Pursuant to this invention, the next available data slot (204) following the system ID (203) supports an outbound secondary control signal (SCS) 30 intended for the adjacent communication system. By using ;7 ;23 3 8 2 9 ;CM-00520H ;the system ID (203) as the marker, the adjacent system can correctly identify and respond as appropriate to the secondary control signalling that has been transmitted by the sourcing system. ;5 Typical outbound primary control signalling words ;(201) usually contain 76 bits of information, plus an additional 8 bits of frame sync information. In one embodiment of this invention, the secondary control signalling word (204) can utilize a higher bit rate, thereby 10 increasing the data rate by perhaps a factor of 10. For example, the outbound secondary control signal word could hold from 760 to 840 bits of data presuming a transmission rate of about 36 K BPS. By using this higher data rate, capacity of the control communication resource will not be 15 substantially impaired. At the same time, the high bit rate will provide satisfactory performance because only fixed site to fixed site communications need be supported. ;So configured, a resource controller can source an appropriate secondary control signal intended for reception 20 and processing by another communication system. Such information could be. for example, to establish intersystem communications between communication units (106) as described below in more detail. ;Referring to Fig. 3, a second embodiment can be seen as 25 depicted generally by the numeral 300. The system (300) again operates in conjunction with other communication systems. For purposes of this description, only two such communication systems (301 and 302) will be described. ;The first communication system (301) again includes a 30 resource controller (303) that functions to control ;£33829 ;CM-00520H ;allocation of a first set of communication resources. In this embodiment, it will be again presumed that the communication resources are supported by a plurality of repeaters (304). and that the communication resources 5 themselves comprise a first set of frequency pairs A-C. and that one of the repeaters (304) supports system control information related to resource allocation requests and grants. The resource controller (303) controls the repeaters (304) and interchanges resource allocation 10 request and grant information through the repeaters (304), via an appropriate link (306). ;The second communication system (302) similarly includes a resource controller (307). repeaters (308) ;(which support communication resources D-F) and an 15 appropriate link (309) therebetween. In this embodiment, the communication resources A-C of the first system (301) are different from the communication resources D-F of the second system (302). Therefore, the two systems (301 and 302) are not able to communicate directly with one another 20 through the repeaters provided. ;In this embodiment, the first communication system (301) also includes a plurality of receivers (311) that are capable of compatibly receiving the communication resources D-F of the second communication system (302). 25 Although it would not necessarily be required that a receiver (311) be provided to accommodate each communication resource of the opposite system, in this embodiment such a receiver (311) has been so provided. An appropriate communication link (312) is provided between 30 the receivers (311) and the resource controller (303) to ;9 ;23 3829 ;CM-00520H ;allow operation of the receivers (311) to be controlled, at least in part, by the resource controller (303), and also to allow the resource controller (303) to receive signalling information as received by the receivers (311) and as 5 sourced from the resource controller (307) of the second system (302). In addition, an appropriate link (313) is provided between the receivers (311) and the repeaters (304) of the first system (301). This link (313) is appropriately gated (314) to allow the resource controller 10 (303) to control provision of signals received by the receivers (311) to the repeaters (304). ;So configured, the resource controller (303) can cause a particular repeater (304) to retransmit a communication, such as a voice message, that has been received by one of 15 the receivers (311). ;A similar group of receivers (316), links (317 and 318) and gate unit (319) are provided in the second communication system (302) to provide an identical configuration as that described above. ;20 Operation of this embodiment may now be described. ;A first communication unit (321) situated within range of the first communication system (301) initiates the process by transmitting a request (322) to communicate with one or more other communication units (although this 25 request could be to communicate with a particular identified talk group, for purposes of simplicity, this description will presume that the first communication unit identifies a particular second communication unit (323) as the desired communication target). This talk request is 30 transmitted on the appropriate control resource for the ;233829 ;10 CM-00520H ;first communication system (301). and is relayed by the appropriate control resource repeater (304.) to the resource controller (303) for the first communication system (301). ;If the resource controller (303) recognizes the 5 communication target as being local (as may be determined, for example, by the ID of the communication target), then the resource controller (303) can allocate a communication resource to support the requested communication as is currently done in the prior art. If, however, the resource 10 controller (303) determines that the communication target is not local (or, if dealing with a talk group, is not completely local in all instances), then the resource controller can transmit, on the control resource, an outbound signalling word constituting a notification that a 15 communication with the second communication unit is desired. ;This outbound communication (324) as sourced by the resource controller (303) and as transmitted by the appropriate control resource repeater (304) will be 20 received by whichever of the receivers (316) in the second communication system (302) is monitoring that particular communication resource of the first system (301). Thai particular receiver (316) will then provide the signalling information via the appropriate link (317) to the resource 25 controller (307) for the second communication system (302). If the second resource controller (307) recognizes the identified communication target as local, the resource controller (307) will assign one of its communication resources to support the communication, and will provide ;11 CM-00520H ;23 3 8 ;M-00520H ;information identifying the allocated resource in an outbound transmission (326) on its control resource. ;This transmission (326) will be received by the second communication unit (323) and cause the second 5 communication unit (323) to begin monitoring the allocated communication resource of the second communication system. This outbound transmission (326) will also be received by the corresponding receiver (311) of the first communication system (301). This received signalling 10 information will be provided to the resource controller (303) thereof via the appropriate link (312). The resource controller (303) can now determine that the communication target has been located and that a communication resource in the second system (302) has been assigned to support the 15 desired communication, will now assign one of its own communication resources to the first communication unit (321) to support the communication. ;Thereafter, the first communication unit (321) will transmit its messages (for example, voice messages) using 20 communication resources of the first communication system (301). The repeater (304) in the first communication system (301) assigned to support this communication will receive these signals from the first communication unit (321) and will repeat them on the 25 allocated communication resource (327). The repeated voice message (327) will be received by the appropriate receiver (316) in the second communication system (302). The resource controller (307) in the second communication system (302) will gate (319) this received voice message 30 to the repeater (308) that has been assigned to support this ;233829 ;12 CM-00520H ;communication. The assigned repeater (308) will then retransmit the received signal (328) and this retransmission will be received by the second communication unit (323). ;5 If the second communication unit (323) were to transmit a response to the first communication unit (321). the same procedure could be implemented in reverse in a transmission trunked mode, or the already allocated resources could be used in a reversed pattern to 10 accommodate a message trunked methodology. ;In Fig. 4. a third general embodiment can be seen as depicted generally by the numeral 400. ;In this embodiment, the first communication system (401) comprises a home system. As before, this system 15 includes a resource controller (403) that functions to control allocation of a first set of communication resources for benefit of a plurality of member communication units. In this embodiment, it will be presumed that the communication resources are supported 20 by a plurality of repeaters (404). that the communication resources themselves comprise a first set of frequency pairs A-C. and that one of the repeaters (404) supports system control information related to resource allocation requests and grants. The resource controller (403) controls 25 the repeaters (404) and interchanges resource allocation request and grant information through the repeaters (404). via an appropriate link (405). ;The second communication system (402) similarly includes a resource controller (407). repeaters (408) 30 (which support communication resources D-F) and an ;m829 ;appropriate link (409) therebetween. In this embodiment, the communication resources A-C of the first system (401) are different from the communication resources D-F of the second system (402). Therefore, the two systems (401 and 5 402) are not able to communicate directly with one another through the repeaters provided. ;The second communication system (402) also includes a plurality of receivers (416) that are capable of compatibly receiving the communication resources A-C of 10 the home communication system (406). Although it would not necessarily be required that a receiver (416) be provided to accommodate each communication resource of the opposite system, in this embodiment such a receiver (416) has been so provided. An appropriate communication 15 link (417) is provided between the receivers (416) and the resource controller (407) to allow operation of the receivers (416) to be controlled, at least in part, by the resource controller (407), and also to allow the resource controller (407) to receive signalling information as 20 received by the receivers (416) and as sourced from the resource controller (403) of the home system (401). In addition, an appropriate link (418) is provided between the receivers (416) and the repeaters (408) of the second system (402). This link (418) is appropriately gated (419) 25 to allow the resource controller (407) to control provision of signals received by the receivers (416) to the repeaters (408). ;So configured, the resource controller (407) can cause a particular repeater (408) to retransmit a communication. ;» 233 82 9 ;14 CM-00520H ;such as a voice message, that has been received by one of the receivers (416). ;If desired, a similar group of receivers, links, and gate unit may be provided in the home communication system 5 (401) to provide an identical configuration as that described above for the second system (402). ;The plurality of member communication units for the home system will typically include one or more fleets or groups. Pursuant to this invention, each such group is 10 assigned an ID for each system that the radios are preregistered with. This preregistration includes information regarding whether the ID represents a local group or roaming group. If the ID relates to a roaming (non-home) group, then the preregistration information should \ 15 also include information regarding the home system for that group, including control resource information and the group ID for that home system. To accomplish this, the resource controller (407) for the second system (i.e., the non-home system) can be provided with an appropriate data 20 base (431) that retains such information regarding the preregistered IDs. ;Operation of this embodiment may now be described. ;A communication unit (423) that belongs to a home system group roams out of the home system (401) and into 25 range of the second system (402). This communication unit (423) then locates the appropriate control resource for this system (this can be done in a number of ways; for example, the communication unit (423) can be previously provided with a list of likely adjacent control resources, or the unit 30 (423) can automatically scan for a control resource when it ;23 382 9 ;15 ;CM-00520H ;10 ;15 ;20 ;loses the control resource for its home channel) and transmits (432) a message to the resource controller (407) for the second system to inform the second system of its presence. This message includes the preregistered ID. ;which the resource controller (407) compares against its database (431) to identify the roaming unit (423) as belonging to a preregistered group from the first system (401). ;The resource controller (407) for the second system can then determine that a roamer from the first system (401) has entered the second system (402), and a receiver (416) can be assigned to monitor the control resource of the first system (401). ;A different communication unit (421), belonging to the group having the preregistered ID and being situated within range of the first communication system (401). may at any moment initiate a group call by transmitting a request (422) to communicate with its group. This talk request is transmitted on the appropriate control resource for the first communication system (401), and is relayed by the appropriate control resource repeater (404) to the resource controller (403) for the first communication system (401). ;The resource controller (403) responds to the request by allocating a communication resource to support the requested communication as is currently done in the prior art. The allocation message from the resource controller includes the group ID for that home system (401) (which ID has been preregistered in the second system's (402) ID database (431)). ;* 233829 16 CM-00520H This outbound allocation message (424) as sourced by the resource controller (403) and as transmitted by the appropriate control resource repeater (404) will be received by whichever of the receivers (416) in the second 5 communication system (402) is monitoring that particular communication resource of the first system (401). That particular receiver (416) will then provide the signalling information via the appropriate link (417) to the resource controller (407) for the second communication system 10 (402). The second resource controller (407) will recognize the ID as belonging to a roamer located in its system, and the resource controller (407) will assign one of the receivers (416) to monitor the allocated communication resource from the first system (401). The controller (407) 15 will also assign one of its own communication resources to support the communication, and cause an allocation message (426) to be transmitted. This allocation will occur in the usual manner via the control resource of the second system (402), and will be received by the second 20 communication unit (423) and cause the second communication unit (423) to begin monitoring the allocated communication resource of the second communication system.

Thereafter, the first communication unit (421) will 25 transmit its messages (for example, voice messages) using communication resources of the first communication system (401). The repeater (404) in the first communication system (401) assigned to support this communication will receive these signals from the first 30 communication unit (421) and repeat them on the allocated # 17 23 3 8 2 9 CM-00520H communication resource (427). The repeated voice message (427) will be received by the appropriate receiver (416) in the second communication system (402). The resource controller (407) in the second communication system (402) 5 will gate (419) this received voice message to the repeater (408) that has been assigned to support this communication. The assigned repeater (408) will then retransmit (428) the received signal and this retransmission will be received by the second 10 communication unit (423). thereby including the second communication unit (423) in the group call.

Eventually, of course, the roaming unit (423) will leave the second system (402) and return to its home system (401). When this occurs, the roaming unit (423) will lose 15 contact with the second system (402) and subsequently gain contact with the home system (401). Upon detecting the control resource of the home system (402), the roaming unit (423) will again register itself with the home system (401). As part of this process, the home system (401) will 20 transmit a registration acknowledgement to the roaming unit (423) on the appropriate control resource. The second system (402), which is still monitoring the control resource for the home system (401). will detect this acknowledgement, and determine that the roaming unit 25 (423) is no longer within the second system (402). The second system (402) will then deassign the roaming unit (423) and de-allocate the receiver (416) that had been previously allocated to monitor the home system (401).

What is claimed is:

Claims (17)

WHAT WE CLAIM IS:

1. A communication system that supports communications amongst a plurality of member communication units, the communication system having: a first set of communication resources that are allocatable amongst the member communication units, wherein at least one of the communication resources supports primary control signalling for use by the member communication units to facilitate allocation of the communication resources amongst the member communication units; and a resource controller for allocating the communication resources amongst the member communication units and for sourcing, at least in part, the primary control signalling; wherein: A) the at least one of the communication resources also supports secondary control signalling for use by at least one other communication system to facilitate system-to-system communications; B) the resource controller sources, at least in part, the secondary control signalling; and C) the primary control signalling and secondary control signalling are not directly compatible. N.Z. *v-;13 AL'c *992 -19-

2. The communication system of claim 1 wherein the communication resource that supports the primary control signalling comprises a dedicated control resource.

3. The communication system of claim 2 wherein the dedicated control resource also supports the secondary control signalling.

4. The communication system of any one of claims 1 to 3 wherein the primary control signalling includes data transmitted at a first data rate, and the secondary control signalling includes data transmitted at a second data rate, wherein the first data rate is different than the second data rate.

5. The communication system of claim 4 wherein the first data rate is slower than the second data rate.

6. The communication system of claim 4 wherein the dedicated control resource supports a slotted Aloha protocol.

7. The communication system of claim 6 wherein the secondary control signalling is transmitted in an Aloha slot separate from the primary control signalling. 13 AUG 1992

8. The communication system of claim 1 wherein the communication system further includes receiver means for receiving secondary control signalling from at least one other communication system.

9. A communication system that supports communications amongst a plurality of member communication units, the communication system having: a first set of communication resources that are allocatable amongst the member communication units, wherein at least one of the communication resources supports primary control signalling for use by the member communication units to facilitate allocation of the communication resources amongst the member communication units; and a resource controller for allocating the communication resources amongst the member communication units and for sourcing, at least in part, the primary control signalling; wherein: (A) the at least one of the communication resources also supports secondary control signalling for use by at least one other independent communication system to facilitate system-to-system communications; (B) the resource controller sources, at least in part, the secondary control signalling; and (C) the primary control signalling and secondary-control signalling are not directly compatible. 13 AO3i -21-

10. The communication system of claim 9 wherein the communication resource that supports the primary control signalling comprises a dedicated control resource.

11. The communication system of claim 10 wherein the dedicated control resource also supports the secondary control signalling.

12. The communication system of claim 11 wherein the primary control signalling includes data transmitted at a first data rate, and the secondary control signalling includes data transmitted at a second data rate, wherein the first data rate is different than the second data rate

13. The communication system of claim 12 wherein the first data rate is slower than the second data rate.

14. The communication system of claim 12 wherein the dedicated control resource supports a slotted Aloha protocol.

15. The communication system of claim 13 wherein the secondary control signalling is transmitted in an Aloha slot separate from the primary control signalling. N.Z. P/-~ 13 -22-

16. The communication system of claim 9 wherein the communication system further includes receiver means for receiving secondary control signalling from at least one other independent communication system.

17. A communication system substantially as herein described with reference to the accompanying drawings. 13