Browse Prior Art Database

ENHANCED RUTHLESS PREEMPTION

IP.com Disclosure Number: IPCOM000007177D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-04
Document File: 1 page(s) / 64K

Publishing Venue

Motorola

Related People

Gary Grube: AUTHOR [+2]

Abstract

A feature called Ruthless Preemption is some- times used on trunked radio systems serving public safety organizations. Trunked radio systems have lim- ited number of channel resources and from time to time they may all be assigned to active communica- tions. During this time, new call requests become "blocked" since there are no channel resources avail- able to service their call request. Since some ofthese new call requests may be more important than the calls that are currently active, the Ruthless Preemp- tion mechanism allows an "emergency" call request to displace an existing call in progress. The trunking infrastructure signals radio units involved in a call that will be displaced, to return to the idle mode on the system control channel. Then the new unit and its group are assigned to that "free" channel to carry out their emergency communication.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 57% of the total text.

Page 1 of 1

MO-LA Technical Developments VoluTe 22 June1994

ENHANCED RUTHLESS PREEMPTIO;~

by Gary Grube and Bernie Olson

BACKGROUND

SOLUTION

  A feature called Ruthless Preemption is some- times used on trunked radio systems serving public safety organizations. Trunked radio systems have lim- ited number of channel resources and from time to time they may all be assigned to active communica- tions. During this time, new call requests become "blocked" since there are no channel resources avail- able to service their call request. Since some ofthese new call requests may be more important than the calls that are currently active, the Ruthless Preemp- tion mechanism allows an "emergency" call request to displace an existing call in progress. The trunking infrastructure signals radio units involved in a call that will be displaced, to return to the idle mode on the system control channel. Then the new unit and its group are assigned to that "free" channel to carry out their emergency communication.

  However, since a typical radio unit is half-duplex, the radio unit that is currently transmitting on the old call will not receive the signal from the infra- structure to return to the idle mode. This can result in interference as it may still be transmitting on the same channel as the new call, i.e. the unit with the new emergency will contend with the old transmit- ting unit. A loss ofcommunication may result.

  A typical trunked radio system uses analog FM modulation. It is well known...