Trunked radio repeater system

• US 5,574,788 A
• Filed: 04/19/1995
• Issued: 11/12/1996
• Est. Priority Date: 06/03/1987
• Status: Expired due to Term

• Current Assignee: Pine Valley Investments, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dissosway, Marc A., Cooper, Gerald M., Hughes, Houston H. III, Childress, Jeffrey S.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/425,152
• Time in Patent Office: 573 Days
• Field of Search: 380/9, 380/31, 380/33, 455/7-9, 455/17, 455/33.1, 455/34.1, 455/34.2
• US Class Current: 455/509
• CPC Class Codes: H04L 1/14 in which the signals are sent back to the transmitter to be checked ; echo systems
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 25/06 Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. During transmission trunking, called and calling receivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with to ensure continuity over an entire conversation. Additional functions and fault tolerant features further increase the versatility and reliability of the system.

Claims

1. A method of communication within a trunked radio repeater system having a full duplex digital control channel and plural working channels, which working channels are assigned for temporary use of individual radio units specified by digital control signals on the control channel comprising,

requesting and receiving assignment of a specific working channel over said control channel with 9600 bits per second digital signals,

automatically switching to an assigned working channel,

engaging in a digital communication session over said working channel, and

releasing said working channel at the end of a communication session for reassignment by said control channel.

2. A method as in claim 1 wherein said communication session is a digital voice communication session.

3. A method as in claim 2 further comprising encrypting said digital voice.

4. A method as in claim 2 further comprising encrypting said digital voice and transmitting said encrypted digital voice at 9600 baud.

5. A method as in claim 1 further comprising transmitting the identity of each unit when that unit is transmitting.

6. A method as in claim 1 further comprising monitoring said control channel for a communique initiated by a calling unit, recording the identity of the calling unit at the called unit, and initiating a call back to said calling unit using said recorded identity.

7. A method as in claim 1 further comprising voting the most reliable of a plurality of received input signals from a unit for processing as the received signal.

8. A method as in claim 1 wherein said engaging in a communication session over said working channel is via a modem.

9. A method as in claim 1 wherein said engaging in a communication session over said working channel is via a public switched telephone network.

10. A method as in claim 1 further comprising monitoring a primary and alternate possible control channels for a control channel data format.

11. A method as in claim 1 further comprising distributing control of the system in the absence of central control by a central controller.

12. A trunked radio repeater system for achieving temporary communication between calling units and called units over controller assigned working channels comprising,

a full duplex digital control channel,

plural working channels,

said control channel carrying 9600 bps digitally encoded request, working channel assignment, and acknowledgment signals,

said working channels being fully duplexed and carrying digital communication signals at 9600 bps,

means at said calling units and said called units for monitoring said control channel and for switching to an assigned working channel assigned over said control channel,

means for subsequently transmitting digital channel assignment late entry messages on said control channel to permit the late entry of a called unit specified by said digital channel assignment, and

means for specifying the identity of the calling unit and the identity of the called unit in each transmission.

13. A trunked radio repeater system as in claim 12 wherein said working channels support analog voice communication.

14. A trunked radio repeater system as in claim 12 further comprising

alternate control channels and means for successively monitoring said channels in a predetermined sequence until an active control channel is discovered.

15. A trunked radio repeater system as in claim 12 wherein said working channels support encrypted voice communication, digital signaling, digital data and analog voice transmissions.

16. A trunked radio repeater system as in claim 12 further comprising a call site controller,

said site controller including means for receiving channel requests,

means for making channel assignments,

means for polling and

means for voting.

17. A trunked radio repeater system as in claim 12 and further comprising an interconnect to a public telephone network.

18. A method of radio communication within a trunked radio communications system having a digital RF control channel and at least one RF working channel, which working channel is assigned for temporary use by individual radio units based on digital trunking control signals sent over the digital RF control channel, said method comprising,

sending substantially 9600 bits per second digital channel request signals over said digital RF control channel,

receiving substantially 9600 bits per second digital channel assignments over said digital RF control channel,

automatically switching to an assigned working channel based on said received digital channel assignment signals,

engaging in digital RF communications over said assigned working channel, and

releasing said assigned working channel subsequent to said engaging step for reassignment.

19. A method as in claim 18 wherein said digital RF communications over said assigned working channel comprises digital voice communications.

20. A method as in claim 19 further comprising encrypting said digital voice.

21. A method as in claim 20 further comprising transmitting said encrypted digital voice at 9600 baud.

22. A method as in claim 18 further comprising transmitting the identity of each unit when that unit is transmitting.

23. A method as in claim 18 further comprising monitoring said control channel at a unit for a communique initiated by a calling unit, recording the identity of the calling unit at the called unit, and initiating a call back to said calling unit using said recorded identity.

24. A method as in claim 18 further comprising voting the most reliable of a plurality of received input signals from a unit for processing as the received signal.

25. A method as in claim 18 wherein said engaging in communications over said working channel is via a modem.

26. A method as in claim 18 wherein said engaging in communications over said working channel is at least in part via a public switched telephone network.

27. A method as in claim 18 further comprising monitoring a primary and alternate possible control channels for a control channel data format.

28. A method as in claim 18 further comprising distributing control of the system in the absence of central control by a central controller.

29. In a trunked radio repeater system for achieving RF communication between calling units and called units over controller assigned working channels a method comprising,

carrying digitially encoded working channel request and working channel assignment signals substantially at 9600 bps over a full duplex digital RF control channel,

carrying digital voice communication signals substantially at 9600 bps over at least one working channel,

monitoring said control channel at said calling units and said called units and switching to an assigned working channel based on said working channel assignment signals carried over said control channel,

subsequently transmitting digital channel assignment late entry messages on said control channel to permit the late entry of a called unit specified by said digital channel assignment, and

specifying the identity of the calling unit and the identity of the called unit in at least some of the transmissions.

30. A method as in claim 29 further including supporting analog voice communication over said working channel.

31. A method as in claim 29 further comprising

successively monitoring said channels in a predetermined sequence until an active control channel is discovered.

32. A method as in claim 29 further comprising supporting encrypted voice communication, digital signaling, digital data and analog voice transmissions over said working channel.

33. A method as in claim 29 further comprising,

receiving channel requests,

making channel assignments,

polling and

voting at a central call controller.

34. A method as in claim 29 further comprising interconnecting to a public telephone network.