Operating a trunked communication system in transmission and message trunked modes

• US 5,864,762 A
• Filed: 08/22/1996
• Issued: 01/26/1999
• Est. Priority Date: 06/03/1987
• Status: Expired due to Fees

• Current Assignee: Com-Net Ericsson Canada Corp., Com-Net Ericsson Critical Radio Systems, Inc.
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dissosway, Marc A., Hughes, Houston H. III, Childress, Jeffrey S., Cooper, Gerald M.
• Primary Examiner(s): Vo, Nguyen
• Assistant Examiner(s): Kincaid, Lester G.
• Application Number:
  US08/697,330
• Time in Patent Office: 887 Days
• Field of Search: 455/15, 455/17, 455/33.1, 455/34.1, 455/34.2, 455/54.1, 455/54.2, 455/56.1, 455/509, 455/518, 455/9, 455/517, 455/519, 455/520, 455/521, 455/70, 455/88, 455/550, 455/575, 379/58, 379/63
• 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 and reliability. The mobile radio transceivers transmit channel requests on the control channel at 9600 bps. The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. Radios select between message and transmission trunking based on over-the-air signaling. 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.

Claims

1. In a trunked radio repeater system for achieving RF communication between at least a first radio unit and a second radio unit over an RF working channel temporarily assigned to carry communications between said at least first and second radio units, a method of dynamically specifying transmission trunked or message trunked usage on a call-by-call basis for said temporarily assigned working channel, said method comprising the steps of:

carrying digitally encoded working channel request and assignment signals associated with a call over a full duplex digital RF control channel;

monitoring said control channel at said first and second unit, and switching to a working channel temporarily assigned to said call based on said digitally encoded working channel assignment signals carried over said control channel; and

dynamically specifying transmission trunked or message trunked usage for said call by specifying trunked call type in at least one digital information field included within digitally encoded signals associated with said call that are carried over at least one of said control channel or said temporarily assigned working channel.

2. A method as in claim 1 further comprising the steps of:

storing, in one of said first and second radio unit, the identity of the other unit in response to receipt of said channel assignment signals; and

in response to a specified call type indicating transmission trunked usage, automatically generating, with said one radio unit, channel request signals including said stored identity of said other radio unit so as to automatically generate channel request signals on the control channel to call back the other radio unit over a further temporarily assigned working channel.

3. The method as in claim 2, wherein the step of automatically calling back is performed with no channel hang time and includes sending at least some 9600 bps signaling over the control channel.

4. The method as in claim 2, wherein said first and second units each include push to talk (PTT) switches, and the step of automatically calling back is performed if the push to talk (PTT) switch of the one unit is depressed within a predetermined time after release of the push to talk (PTT) switch of the other unit.

5. A method as in claim 1 wherein:

said dynamically specifying step includes transmitting over the air with at least one radio repeater substantially at 9600 bits per second on at least one of said control channel or said temporarily assigned working channel, a digital transmission/message trunked status signal identifying whether the usage of the temporarily assigned working channel is to be transmission or message trunked; and

wherein said method further includes controlling call termination timing with at least one of said first and second radio units based at least in part on said trunked status signal.

6. A method as in claim 1 wherein said carrying step comprises carrying said digitally encoded working channel request and assignment signals over said digital control channel at a rate of substantially 9600 bps and using a substantial portion of the 9600 bps signalling rate capacity to provide enhanced signalling reliability.

7. A method as in claim 1 further including carrying voice signals between said first and second units over said temporarily assigned working channel.

8. A method as in claim 1 further including carrying digital signals substantially at 9600 bps over said temporarily assigned working channel, and using a substantial portion of the 9600 bps signalling rate capacity to provide enhanced signalling reliability.

9. A method as in claim 1 further including specifying the identity of said first radio unit and the identity of said second radio unit in at least some of said digitally encoded signals, and wherein said dynamically specifying step comprises including, within said digitally encoded signals, at least one digital message/transmission trunking bit that determines, independently of said first radio unit identity and said second radio unit identity, whether said first and second radio units are to engage in a transmission trunked call or in a message trunked call.

10. A method as in claim 1 wherein said dynamically specifying step comprises including, within digitally encoded signals transmitted over said temporarily assigned working channel, at least one digital message/transmission trunking bit that determines whether said first and second radio units are to engage in a transmission trunked call or in a message trunked call.

11. A method as in claim 1 further including automatically inhibiting, in a transmission trunked usage, one of said first and second radio units from transmitting on said temporarily assigned working channel.

12. A method as in claim 1 further including deallocating said temporarily assigned working channel:

(a) in a transmission trunked usage, in response to unkeying of said first radio unit, and

(b) in a message trunked usage, a predetermined time following unkeying of either said first radio unit or second radio unit, unless the other radio unit keys within said predetermined time.

13. A method as in claim 1 further including, in a transmission trunked usage, substantially immediately reverting said first and second radio units to said control channel upon unkeying, and freeing said temporarily assigned working channel for reassignment.

14. A method as in claim 1 further including, in transmission trunked usage, beginning to transmit channel drop signaling on said temporarily assigned working channel in response to receipt of an unkey message from a transmitting one of said first and second radio units without waiting for said transmitting radio unit to switch to a receive operation for reliably detecting said channel drop signaling.

15. Apparatus for achieving reliable and prompt communication within a trunked radio repeater system having a 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, said apparatus comprising:

at least one repeater transceiver that transmits and receives, over said control channel and over at least one temporarily assigned working channel, digital signals associated with a particular communique; and

at least one mobile or portable radio transceiver that receives and detects as part of said digital signals associated with said particular communique, on at least one of said control channel or an assigned working channel, a call type signal identifying whether the usage of the working channel for said particular communique is to be transmission or message trunked.

16. A method of operating a digitally trunked radio communication system including at least one radio unit capable of operating in either of a transmission trunked mode and a message trunked mode, said method comprising the steps of:

(a) sending, over the air as part of digital signalling associated with a particular communique involving said radio unit;

(1) a first digital code identifying said radio unit;

(2) a second digital code identifying a working channel, and

(3) a third digital code specifying transmission or message trunking usage of said identified working channel for said particular communique;

(b) receiving said first, second and third digital codes with said radio unit; and

(c) in response to said digital codes received by said receiving step (b), temporarily operating said radio unit identified by said first digital code, for that particular communique, on said working channel identified by said second code in said trunking mode identified by said third digital code.

17. A method as in claim 16 further comprising the steps of:

leaving said working channel and returning to said digital control channel substantially immediately upon completion of a transmission, when said third digital code has a first predetermined value indicating transmission trunking; and

waiting on said working channel for a predetermined delay time after completion of a transmission to receive a possible response from said transmission over said same temporarily assigned working channel, when said third digital code has a second predetermined value indicating message trunking.