Method and apparatus for detecting and handling collisions in a radio communication system

• US 5,619,530 A
• Filed: 03/07/1996
• Issued: 04/08/1997
• Est. Priority Date: 04/04/1994
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Fulghum, Tracy L., Cadd, Jimmy W.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Le, Amanda T.
• Application Number:
  US08/612,395
• Time in Patent Office: 397 Days
• Field of Search: 375/202, 375/205, 375/219, 375/356, 375/358, 375/364, 370/18, 370/32, 370/60, 370/82, 370/85.1-85.4, 370/85.6, 370/91-93, 370/94.1, 370/95.1, 370/95.3, 370/110.1, 370/110.4, 370/111, 340/825.5, 395/299, 395/730, 455/15, 455/16, 455/34.1, 455/49.1, 455/50.1, 455/58.1, 455/58.2
• US Class Current: 375/219
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

A radio communication system (10) has multiple transceivers (12, 14) attempting to initiate communications on a shared communication channel substantially simultaneously. A method for detecting and handling potential channel use collisions is provided for an initiating transceiver (12, 14). The transceiver (12, 14) transmits on the communication channel, a message including an identifying code word. The transceiver (12, 14) then receives data in a predetermined slot of the communication channel, and compares this data with the code word transmitted. A channel use collision is detected when the data received is not equal to the code word transmitted.

Claims

1. In a radio communication system having transceivers sharing a communication channel, a method of detecting and handling channel use collisions occurring when multiple transceivers attempt, substantially simultaneously, to establish a communication link with other transceivers, the method comprising the steps of, at the initiating transceiver:

transmitting a message on the communication channel, the message including a code word particular to the initiating transceiver;

receiving particular data on the communication channel;

comparing the particular data with the code word;

detecting that a channel use collision occurred when the particular data is a combination of different code words and the combination does not correspond to the code word; and

transmitting a collision detect signal on the communication channel after detecting the channel use collision.

2. The method of claim 1, further comprising the steps of:

monitoring the communication channel for a code word dependent time period to detect communication activity; and

re-transmitting the message when communication activity is not detected within the code word dependent time period.

3. The method of claim 2, further comprising the step of participating with other transceivers in a collision handling procedure when communication activity is detected within the code word dependent time period.

4. The method of claim 1, wherein the step of receiving particular data comprises the step of receiving, from a target transceiver, a response to the message including a representation of the code word conveyed in ON/OFF key modulation in a predetermined slot of the communication channel.

5. In a radio communication system having multiple initiating transceivers sharing a communication channel, a method of detecting and handling channel use collisions occurring when multiple initiating transceivers attempt, substantially simultaneously, to establish a communication link with another target transceiver, the method comprising the steps of:

selecting a code word to identify an initiating transceiver;

transmitting, by the initiating transceiver, a message including the code word on the communication channel;

receiving, by a target transceiver, the message from the initiating transceiver;

transmitting, by the target transceiver, a response to the message in a predetermined slot of the communication channel, the response including the code word;

receiving, by the initiating transceiver, data extracted from the predetermined slot of the communication channel;

detecting, by the initiating transceiver, whether a collision occurred by comparing the data with the code word and determining that a collision occurred when the data is a combination of different code words;

establishing, by the initiating transceiver, a communication link with the target transceiver when a collision is not detected; and

executing, by the initiating transceiver, a collision handling procedure when a collision is detected.

6. The method of claim 5, wherein the step of selecting a code word, includes the step of:

randomly selecting a code word of a predetermined size.

7. The method of claim 5, wherein the step of executing comprises the steps of:

monitoring, by the initiating transceiver, the communication channel for a code word dependent time period to detect communication activity; and

re-transmitting, by the initiating transceiver, the message including the code word, when communication activity is not detected within the code word dependent time period; and

detecting and transmitting, by the initiating transceiver, a channel busy signal on the communication channel when communication activity occurs during the code word dependent time period.

8. The method of claim 5, wherein the step of transmitting, by the target transceiver, comprises the step of conveying the code word in ON/OFF key modulation.

9. In a radio communication system having transceivers sharing a communication channel, a method of detecting and handling channel use collisions occurring when multiple transceivers attempt, substantially simultaneously, to establish a communication link with other transceivers, the method comprising the steps of:

providing a code word particular to each of the multiple transceivers;

at a particular transceiver;

initiating transmission on the communication channel;

determining that a collision has occurred on the communication channel with respect to the initiated transmission;

monitoring the communication channel for a particular time period, based on the code word for the particular transceiver, to detect communication activity;

re-initiating transmission on the communication channel when communication activity is not detected within the particular time period; and

participating with other transceivers in a collision handling procedure when communication activity is detected within the particular time period.

10. The method of claim 9, wherein the step of participating includes the steps of:

receiving collision detect signals from other transceivers; and

echoing the received collision detect signals.

11. The method of claim 9, wherein the step of participating includes the steps of:

receiving channel busy signals from other transceivers; and

echoing the received channel busy signals.