Browse Prior Art Database

INTEGRATION OF MULTIPLE CALLS IN A TRUNKED RADIO SYSTEM

IP.com Disclosure Number: IPCOM000009767D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-17
Document File: 2 page(s) / 130K

Publishing Venue

Motorola

Related People

Gary J. Aitkenhead: AUTHOR [+3]

Abstract

A mobile communications system generally consists of a plurality of radio base stations interconnected via a land-based wireline network. Such a system can support group communications where the call may be routed to several base station sites so that subscriber units in coverage of those sites can hear the transmissions for that group communication. On occasion, the wireline network fails or has limited resources in which case the group communication is confined to a single base station site or to a limited sub-set of sites within the network. This situation can result in multiple group communications for the same talkgroup taking place simultaneously in two or more of these "islands" where network connectivity is temporarily unavailable. When the network connections are restored, it may be desirable to re-integrate the separate calls for the same group. Similarly when a wide-area group call loses link capacity to higher priority traffic, it may be that the call is broken up into multiple "islands" where the call can continue but without capturing the entire group area.

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MOTOROLA

Technical Developments

INTEGRATION OF MULTIPLE CALLS IN A TRUNKED RADIO SYSTEM

by Gary J. Aitkenhead, Surender Kumar and Robert E. Balgeman

INTRODUCTION

A mobile communications system generally consists of a plurality of radio base stations interconnected via a land-based wireline network. Such a system can support group communications where the call may be routed to several base station sites so that subscriber units in coverage of those sites can hear the transmissions for that group communication. On occasion, the wireline network fails or has limited resources in which case the group communication is confined to a single base station site or to a limited sub-set of sites within the network. This situation can result in multiple group communications for the same talkgroup taking place simultaneously in two or more of these "islands" where network connectivity is temporarily unavailable. When the network connections are restored, it may be desirable to re-integrate the separate calls for the same group. Similarly when a wide-area group call loses link capacity to higher priority traffic, it may be that the call is broken up into multiple "islands" where the call can continue but without capturing the entire group area.

This article proposes an improved method by which multiple calls involving the same talkgroup can be integrated into a single call as network connections become available without waiting for the calls to end.

PROBLEM STATEMENT

Current SmartZone trunked systems can support simultaneous calls for the same group when a site link fails and the site operates in site-only trunking mode. When the site link is restored, the call is transmission trunked. This operation means that the wide area and site-only call are not integrated until the call ends. Furthermore, this operation is utilized for single site trunking in the case of link failure.

Such operation does not cover the case where the

Motorola. Inc. 2000

system is designed with fewer inter-site links than over-air channels and calls need to be integrated when the inter-site resources become available.

iDEN also has a mechanism at call set-up which integrates a new cell into an existing group call by joining the new requester as a receiver in the call (if another group member is already transmitting) and thus enlarging the area of the group call. However, this mechanism does not work for integrating calls with two talking parties that need to be joined after fIXed links become available.

PROPOSED SOLUTION

The improved methods described here assume that a means for interrupting a currently talking unit exists, such as is possible with TDMA time-division duplex. Other methods to interrupt a talker such as full-duplex FDMA also eJiist. The methods apply to any system where group calls need to be re-integrated; the reason why the calls are fragmented in the fIrst place is not important.

GROUP CALL FRAGMENTATION

An ongoing group call, which loses link capacity, can result in...