Method for resolving call collisions in a digital conventional direct mode

Abstract

A process for resolving call collisions in a digital conventional direct mode includes monitoring a direct mode communication channel for transmissions from other direct mode radios in the plurality of direct mode radios. In response to detecting a new call request: identifying a last radio to transmit on the direct mode channel, transmitting a new call request for receipt by the last direct mode radio to transmit, monitoring the direct mode channel for a response from the last radio to transmit, and if a call grant granting the new call request is received from the last radio to transmit, initiating the new direct mode call on the direct mode communication channel. If the call grant is not received, at least temporarily refraining from initiating the new direct mode call.

Description

FIELD OF THE DISCLOSURE[0001]The present disclosure relates generally to wireless communications and more particularly to direct mode call collision avoidance in a digital conventional direct mode communications system.BACKGROUND[0002]The European Telecommunications Standard Institute-Digital Mobile Radio (ETSI-DMR) is a direct digital replacement for analog Private Mobile Radio (PMR). DMR is a scalable system that can be used in unlicensed mode (in a 446.1 to 446.2 MHz band), and in licensed mode, subject to national frequency planning ETSI standards or specifications referred to herein may be obtained by contacting ETSI at ETSI Secretariat, 650, route des Lucioles, 06921 Sophia-Antipolis Cedex, FRANCE.[0003]DMR provides improved range, higher data rates, more efficient use of spectrum, and improved battery life over prior direct mode protocols. Features supported include fast call set-up, calls to groups and individuals, and short data and packet data calls. Supported communicatio...

AI Technical Summary

Problems solved by technology

However, in a digital conventional direct mode consistent with any one of the foregoing mentioned standards, two or more sources transmitting simultaneously would corrupt both of the digital transmissions and, as a result, the recipients would not hear any conversation.

Even worse, the simultaneously transmitting digital radio users would not be aware of the corrupted transmission and may (incorrectly) assume that the transmissions reached their respective targeted group of recipient digital direct mode radios.

This issue is further exacerbated in digital direct mode group calls, where the number of digital direct mode radios in the group (e.g., more than five) increases the odds that simultaneous transmissions would conflict.

Returning to step 416, if it is determined that no other call grants have been received on the direct mode channel, the initiating direct mode radio may assume that there was some problem in transmitting the new call request to the arbitrating radio, some problem in the arbitrating radio processing the request, or some problem in receiving the call grant at the initiating radio, among other possibilities.

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