Processor-to-processor communications protocol for a public service trunking system

• US 5,128,930 A
• Filed: 03/08/1991
• Issued: 07/07/1992
• Est. Priority Date: 08/14/1987
• Status: Expired due to Term

• Current Assignee: Pine Valley Investments, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: General Electric Company
• Inventors: Yurman, Bruno, Hughes, Houston H. III, Hattey, David L., Gordon, Robert T., Nazarenko, Dimitri M.
• Primary Examiner(s): TON, DANG T
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US07/666,841
• Time in Patent Office: 487 Days
• Field of Search: 340/94.1, 340/60, 340/99, 370/58.2
• US Class Current: 370/340
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A downlink between a communications dispatch console and a digitally trunked radio repeater system site controller efficiently transfers message data between the site controller and the console over a standard 9.2 kilobit per second landline. A downlink trunking card identical in structure to trunking cards used in the preferred embodiment system for RF channel signal processing interfaces the site controller with the landline link. A similar trunking card on the other side of the landline link interfaces the dispatch console processor with the landline link. Message protocol and format is translated between the site controller and the landline link and between the landline link and the dispatch console. Data buffering at each end of the landline link maximizes data transfer rate over the landline, and in addition, a priority scheme insures that more important messages are transmitted over the downlink before less important messages. Retransmit-until-acknowledged protocol is used to insure reliable message transfer--and also to permit receiving units along the downlink to slow down transmitting units in order to avoid message traffic blockage.

Claims

1. A method of communicating digital signals between an RF repeater site controller and a telephone switching network over a downlink digital signal data link, said method comprising the steps of:

(A) transmitting messages from said site controller to a downlink trunking card module in the following format;

(a1) start frame byte,

(a2) operational code byte,

(a3) a variable number N of data bytes, and

(a4) a checksum byte;

(B) converting, at said downlink trunking card module, said message transmitted by said transmitting step (A) into the following format;

(b1) Barker code bytes,

(b2ll ) said operational code byte,

(b3) a packet begin character,

(b4) said variable number N of data bytes, and

(b5) at least one checksum byte different from said first-mentioned checksum byte;

(C) transmitting said message converted by said converting step (B) from said downlink trunking card module to a switch trunking card module

(D) converting, at said switch trunking card module, said, message transmitted by said transmitting step (C) into the following format;

(d1) a MID code corresponding to said operational code byte,

(d2) a TLY byte specifying the number of data bytes to follow,

(d3) source and destination bytes indicating the source and destination of said message,

(d4) said variable number N of data bytes, and

(d5) a further checksum byte different from said first-mentioned and second-mentioned checksum bytes; and

(E) transmitting said data converted by said converting step (D) to said switch.

2. A method of communicating digital signal between an RF repeater site controller and a telephone switching network over a downlink digital signal data link, said method comprising the steps of:

(A) receiving messages from said site controller with a downlink trunking card module in the following format;

(a1) start frame byte,

(a2) operational code byte,

(a3) a variable number N of data bytes, and

(a4) a checksum byte;

(B) converting, at said downlink trunking card module, said messages received by said receiving step (A) into the following format;

(b1) Barker code bytes,

(b2) said operational code byte,

(b3) a packet begin character,

(b4) said variable number N of data bytes, and

(b5) at least one checksum byte different from said first-mentioned checksum byte; and

(C) transmitting said message converted by said converting step (B) from said downlink trunking card module to a switch trunking card module.

3. A method of communicating digital signals between an RF repeater site controller and a telephone switching network over a downlink digital signal data link, said method comprising the steps of:

(A) receiving a message with a switch trunking card module in the following format;

(a1) Barker code bytes,

(a2) an operational code byte,

(a3) a packet begin character,

(a4) an variable number N of data bytes, and

(a5) at least one checksum byte; and

(B) converting, at said switch trunking card module, said message received by said receiving step (A) into the following format;

(b1) a MID code corresponding to said operational code byte,

(b2) a TLY byte specifying the number of data bytes to follow,

(b3) source and destination bytes indicating the source and destination of said message,

(b4) said variable number N of data bytes, and

(b5) a further checksum byte different from said first-mentioned checksum byte; and

(C) transmitting said data converting by said converting step (B) to a switch.

4. A method of communication digital signals between an RF repeater site controller and a telephone switching network over a downlink digital signal data link, said method comprising the steps of:

(A) transmitting messages from said site controller to a node on said downlink in the following format;

(a1) start frame byte,

(a2) operational code byte,

(a3) a variable number N of data bytes, and

(a4) a checksum byte;

(B) converting, at said downlink node, said message transmitted by said transmitting step (A) into the following format;

(b1) a MID code corresponding to said operational code byte,

(b2) a TLY byte specifying the number of data bytes to follow,

(b3) source and destination bytes indicating the source and destination of said message,

(b4) said variable number N of data bytes, and

(b5) a further checksum byte different from said first-mentioned checksum bytes; and

(C) transmitting said data converted by said converting step (B) to a switch.