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METHOD TO ARBITRATE CONTENTION BETWEEN SPEECH FRAMES FROM MULTIPLE VOCODED SPEECH SOURCES

IP.com Disclosure Number: IPCOM000009078D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-06
Document File: 2 page(s) / 105K

Publishing Venue

Motorola

Related People

James Mathis: AUTHOR [+4]

Abstract

In a radio communication system built using a distributed transport system, such as IP, and without service-level coordination, multiple users can attempt to talk simultaneously, resulting in multiple vocoded voice streams for the same destination talk- group.

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@ MO-LA Technical Developments

METHOD TO ARBITRATE CONTENTION BETWEEN SPEECH FRAMES FROM MULTIPLE VOCODED SPEECH SOURCES

by James Mathis, Mark Shaughnessy, Surender Kumar and Bhavesh Pate1

THE PROBLEM

  In a radio communication system built using a distributed transport system, such as IP, and without service-level coordination, multiple users can attempt to talk simultaneously, resulting in multiple vocoded voice streams for the same destination talk-

group.

  In a typical system implementation, one base site controller will be connected to other base sites using a high-capacity packet-switched network. In the case of a single talker, when a speech packet arrives at a site and the assigned RF channel is idle, the speech packet is queued for transmission. In the case of multiple potential talkers, unless restricted by some type of strict talker control at the services level, multiple subscribers may potentially decide to start talking simultaneously. Such an occurrence results in vocoded voice packets from multiple talk- ers to the same destination simultaneously arriving at a site controller. In a normal packet-switched sys- tem, the packets would be queued for transmission over the radio channel based on arrival ordering or priority or some similar scheduling mechanism. Because of the unique characteristics of the digital vocoders used in land mobile systems, multiple voice streams cannot be interleaved or simultane- ously decoded and maintain acceptable speech qual- ity. Additionally, the base site controller would be accepting more speech frames over its site link than it can send over the assigned radio channel, result- ing in buffering problems in the site controller. While voice services can be defined that provide strict speaker control, a generic connection plane must be capable of supporting less well- structured services.

THE SOLUTION

The solution entails using techniques for arbitrating at the base site conntroller between the

multiple vocoded speech stream...