Fail-soft architecture for public trunking system

• US 5,274,838 A
• Filed: 07/16/1992
• Issued: 12/28/1993
• Est. Priority Date: 06/03/1987
• Status: Expired due to Term

• Current Assignee: Pine Valley Investments, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hughes, Houston H. III, Childress, Jeffrey S.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): KEOUGH, TIMOTHY
• Application Number:
  US07/913,906
• Time in Patent Office: 530 Days
• Field of Search: 455/9, 455/14, 455/17, 455/34.1, 455/53.1, 379/58
• US Class Current: 455/9
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A site architecture for a trunked radio frequency communications system provides better fault tolerance capabilities than are available from architectures including redundant hardware. During normal system operations, a primary site controller performs most or all system control functions while signal processing functions are performed in a distributed manner by trunking cards associated with individual repeater channel receivers and transmitters. In the event the site controller fails, the trunking cards also begin performing trunking and other control functions. The trunking cards cease attempting to communicate with the failed site controller, and begin communicating directly with one another via a high speed backup serial link. Through the distributed processing routines performed by the various trunking cards and interaction between the trunking cards over the backup serial link, trunking and other capabilities are maintained even though the primary site controller has failed (although advanced features such as call logging and the like are lost). Because trunking capability is maintained, failure of the primary site controller has little or no effect on ongoing communications and is virtually transparent to mobile unit operators.

Claims

1. In a trunked RF communications repeater architecture providing an RF control channel and plural trunked RF communications channels for temporary assignment to remote RF transceivers in response to digital control signals passed over the RF control channel, said repeater architecture being adapted for connection to a centralized site controller performing at least some trunking related operations, an improvement comprising the step of operating said repeater architecture in a failsoft mode which trunks said plural RF channels when said centralized site controller fails or is absent.

2. A method as in claim 1 further including the following steps:

(a) in a normal operating mode, temporarily assigning, based on control of said centralized site controller, said plural RF channels for use by said remote RF transceivers; and

(b) in said failsoft mode, temporarily assigning, based on control of a repeater associated with said control channel, said plural RF channels for use by said remote RF transceivers.

3. In a trunked RF communications repeater architecture which supports an RF control channel and plural trunked RF communications channels for temporary assignment to remote RF transceivers in response to digital control signals passed over the RF control channel, said repeater architecture adapted for connection to a centralized site controller that performs at least some trunking related operations, an improvement comprising an arrangement which operates said repeater architecture in a failsoft mode that trunks said plural RF channels when said centralized site controller fails or is absent.

4. In a trunked RF communications repeater system providing an RF control channel and plural trunked RF communications channels, said repeater system temporarily assigning said plural trunked RF channels for use by mobile RF transceivers in response to digital control signals passed over the RF control channel, said repeater system being adapted for connection to a centralized site controller, an improvement comprising operating said repeater system in a mode which maintains trunking capability upon failure or absence of said centralized site controller.

5. In a trunked RF communications repeater system providing an RF control channel and plural trunked RF communications channels, said repeater system temporarily assigning said plural trunked RF channels for use by mobile RF transceivers in response to digital control signals passed over the RF control channel, said repeater system being adapted for connection to a centralized site controller, said repeater system including an arrangement that operates said repeater system in a mode which maintains trunking capability upon failure or absence of said centralized site controller.

6. In a trunked RF communications system providing an RF control channel and plural trunked RF communications channels, said system including centralized trunking processor that normally temporarily assign said plural trunked RF channels to RF transceivers in response to digital control signals passed over the RF control channel, said system including a failsoft arrangement which operates in a failsoft mode to maintain trunking capabilities upon failure or absence of said centralized trunking processor without need for a backup centralized trunking processor.

7. In a trunked land-mobile RF communications system providing an RF control channel and plural trunked RF communications channels, said system including:

plural RF repeaters;

a centralized digital trunking computer coupled to said plural repeaters which controls said repeaters to temporarily assign said plural RF channels for use by mobile and/or portable RF transceivers in response to digital control signals passed over the RF control channel, and

failsoft means disposed within at least one of said repeaters for maintaining trunking capabilities despite failure or absence of said centralized digital trunking computer.

8. In a land-mobile radio public service trunking RF communications system providing an RF control channel and plural trunked RF working channels, said system performing at least one trunking related operation, said system including:

a centralized digital trunking arrangement which (a) provides digital trunking control so as to perform a first trunking related operation of temporarily assigning said RF working channels for use by mobile and/or portable RF transceivers in response to digital control signals passed over the RF control channel, and (b) controls said system to perform at least a second trunking related operation; and

failsoft means for operating said system to perform said first trunking related operation, but not said second trunking related operation, upon failure of said centralized digital trunking arrangement.

9. A fault-tolerant trunked land-mobile RF communications system which facilitates RF communications between plural mobile and/or portable RF transceivers via plural N RF communications channels, one of said plural N communications channels comprising an RF control channel that carries digital control signals, each of said plural N communications channels having repeater equipment associated therewith, said system including a digital signal link for communicating digital trunking control signals between said repeater equipment, particular repeater equipment associated with one of said plural N channels providing digital trunking control signals over said link to supervise said repeaters to trunk said plural N RF communications channels, said system including a fault tolerant arrangement at said repeater site that detects failure of the particular repeater equipment and, in response to said detected failure, automatically assigns repeater equipment associated with another of said plural N RF communications channels to provide said digital trunking control signals over said link so as to supervise said repeaters to trunk said plural N RF communications channels.

10. A system as in claim 9 wherein the repeater equipment associated with said control channel supervises said repeaters to trunk, and said digital control signals are passed over said control channel substantially at the rate of 9600 baud.

11. In a fault-tolerant trunked land-mobile RF communications system which facilitates RF communications between plural mobile and/or portable RF transceivers via plural N RF communications channels comprising an RF control channel that carries digital control signals, each of said plural N communications channels having repeater equipment associated therewith, said system including a digital signal link for communicating digital trunking control signals between said repeater equipment, the repeater equipment associated with said control channel providing digital trunking control signals over said link to control said other repeaters to trunk said plural N RF communications channels, a fault tolerant method for maintaining trunking capabilities despite component failure including detecting failure of the repeater equipment associated with said control channel and, in response to said detected failure, automatically assigning repeater equipment associated with another of said plural N RF communications channels to control said other repeaters so as to provide trunking of said plural N RF communications channels.

12. A method as in claim 11 further including passing said digital control signals over said control channel substantially at the rate of 9600 baud.

13. A digitally trunked land-mobile RF communications system which provides trunked RF communications between plural mobile and/or portable RF transceivers, said system including plural N trunked repeaters supporting corresponding plural N trunked RF communications channels, one of said plural channels comprising an RF control channel which carries digital signals, said system further including a digital control link communicating digital trunking control signals between said plural N repeaters, one of said repeaters generating synchronization signals for synchronizing signalling across said plural N channels, said system including a fault tolerant arrangement that detects failure of said synchronization signal generation and automatically assigns another of said plural repeaters to generate said synchronization signals in response to said detected failure.

14. A trunked land-mobile RF communications system which provides trunked RF communications between plural mobile and/or portable RF transceivers, said system including plural N trunked repeaters supporting corresponding plural N trunked RF communications channels and further including a control channel repeater which supports a dedicated RF control channel, said system including a digital control link communicating digital control signals between said repeaters, one of said repeaters selecting a free one of said N RF communications channels, in response to digital channel request messages received from an RF transceiver over said RF control channel and sending digital trunking control signals indicating said selected free channel over said digital control link, said system including a fault tolerant arrangement that detects failure of said one repeater and automatically causes another of said plural repeaters to make said selections and send said digital trunking control signals.

15. A trunked land-mobile RF communications system which provides trunked RF communications between plural mobile and/or portable RF transceivers, said system including plural N trunked repeaters operating on corresponding plural N trunked RF communications channels, a control channel repeater receiving digital channel request messages from said RF transceivers, generating digital trunking control signals, and transmitting responsive digital channel assignment messages over an RF control channel so as to temporarily assign said plural N trunked communications channels for temporary use by said RF transceivers, said system including:

a digital control link that passes said digital trunking control signals between said plural N repeaters,

wherein at least said control channel repeater includes a storage device that stores channel assignment related information for each of said plural N trunked RF communications channels and continually updates said stored information in response to said temporary assignments.

16. A system as in claim 15 wherein each of said plural repeaters associated with said N trunked RF channels includes a storage device that stores channel assignment related information corresponding to each of said plural N trunked RF channels in response to said digital trunking control signals passed over said link.

17. A land-mobile RF communications system which facilitates trunked RF communications between plural mobile and/or portable RF transceivers, said system including plural N repeaters supporting corresponding plural N RF communications channels including a dedicated RF control channel, a digital control link communicating digital trunking control signals between said plural N repeaters, a control channel repeater which receives digital channel request messages from said RF transceivers over said RF control channel and transmits responsive digital channel assignment messages over said RF control channel so as to trunk said communications channels for temporary assignment and use by said RF transceivers, wherein at least one of said plural N repeaters generates said digital trunking control signals to control trunking operations for said system.

18. A system as in claim 17 including a fault tolerant arrangement that detects failure of said control channel repeater and automatically removes said control channel repeater from service without loss of said communications channel trunking.

19. A land-mobile RF communications system which facilitates trunked RF communications between plural mobile and/or portable RF transceivers, said system including plural N repeaters supporting corresponding plural N RF communications channels, said system including at least one digital control link for communicating digital trunking control signals between said plural N repeaters, at least one of said repeaters receiving digital channel request messages from said RF transceivers via an RF channel assigned as a dedicated control channel and transmitting responsive digital channel assignment messages over said control channel so as to trunk the others of said plural N RF communications channels for temporary use by said RF transceivers, said control channel repeater controlling the others of said plural N repeaters to perform said trunking, said system including a fault tolerant arrangement that detects failure of any of said repeaters (including said control channel repeater) and automatically removes said failed repeater from service without loss of said trunking.

21. A system as in claim 19 further including a failsoft arrangement that detects failure of any of said plural repeaters and automatically removes said failed repeater from service without loss of said trunking.

20. A digitally trunked land-mobile RF communications system which provides RF communications between plural mobile and/or portable RF transceivers, said system including plural N repeaters operating on corresponding plural N trunked RF communications channels and further including a further repeater that receives channel request messages from said RF transceivers over an RF control channel and transmits responsive channel assignment messages over said RF control channel so as to trunk said communications channels for temporary use by said RF transceivers, wherein said system includes a digital control link that communicates digital trunking control signals between said repeaters to permit said repeaters to control trunking operations without the need for a centralized site controller.

22. A trunked land mobile RF communications repeater system which receives and transmits on plural RF channels, each of said RF channels having repeater equipment associated therewith, one of said RF channels comprising a digital control channel which passes digital control signals to mobile and/or portable RF transceivers, the improvement comprising communicating trunking control signals between said repeater equipment so as to enable said repeater equipment to control trunking of at least some of said RF channels.

23. A trunked land mobile RF communications repeater system which receives and transmits on plural RF channels, each of said RF channels having repeater equipment associated therewith, one of said RF channels comprising a digital control channel which passes digital control signals to mobile and/or portable RF transceivers, the improvement comprising selecting, with at least one of said repeater equipment, a free RF channel for temporary use by a requesting one of said mobile and/or portable RF transceivers.