Browse Prior Art Database

CONVENTIONAL TO TRUNKING CORRELATOR

IP.com Disclosure Number: IPCOM000008100D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-17
Document File: 5 page(s) / 277K

Publishing Venue

Motorola

Related People

Mark Shaughnessy: AUTHOR [+3]

Abstract

Land mobile radio systems can be classified into two major categories, trunked and conventional (also called non-trunked.) Systems of the trunked type are more complex and generally use a resource controller or similar device to allocate communica- tions traffic channels to requesters from among a pool of available channels. This resource allocator acts as a system "brain" to efficiently allocate the Radio Frequency (RF) resources. It uses a so-called control channel, which is usually a dedicated signal- ing channel, to receive service requests from radio units and direct them to the appropriate traffic chan- nel resource. The resource allocator also maintains some level of privacy between system user groups, since it only assigns users involved in a particular conversation to a traffic channel, while all other system users wait in silence, monitoring the control channel. In the simpler conventional system type on the other hand, there is no system "brain," and users are left to select a traffic channel by themselves. Often with conventional systems, user groups are given a permanent channel assignment by a system administrator to help minimize user confusion. Also, with conventional systems there is generally only rudimentary privacy between user groups. Generally, all users tuned to a given channel will hear all conversations on that channel, though some conventional systems also provide so-called private line (PL) or digital private line (DPL) signaling so those user radios that do not recognize a transmitted PL tone or DPL code remain muted.

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MOTOROLA Technical Developments

CONVENTIONAL TO TRUNKING CORRELATOR

by Mark Shaughnessy, Pat Ekstrom, and Ed Tremko

INTRODUCTION

  Land mobile radio systems can be classified into two major categories, trunked and conventional (also called non-trunked.) Systems of the trunked type are more complex and generally use a resource controller or similar device to allocate communica- tions traffic channels to requesters from among a pool of available channels. This resource allocator acts as a system "brain" to efficiently allocate the Radio Frequency (RF) resources. It uses a so-called control channel, which is usually a dedicated signal- ing channel, to receive service requests from radio units and direct them to the appropriate traffic chan- nel resource. The resource allocator also maintains some level of privacy between system user groups, since it only assigns users involved in a particular conversation to a traffic channel, while all other system users wait in silence, monitoring the control channel. In the simpler conventional system type on the other hand, there is no system "brain," and users are left to select a traffic channel by themselves. Often with conventional systems, user groups are given a permanent channel assignment by a system administrator to help minimize user confusion. Also, with conventional systems there is generally only rudimentary privacy between user groups. Generally, all users tuned to a given channel will hear all conversations on that channel, though some conventional systems also provide so-called private line (PL) or digital private line (DPL) signaling so those user radios that do not recognize a transmitted PL tone or DPL code remain muted.

  A common problem for people using trunked and conventional wireless systems today is that it is somewhat difftcult to communicate between sys- tems. This cross-communication need often arises, for example, when one agency in a given city (e.g., a Police user group), using an older conventional system, needs to communicate with another agency

(e.g., a Fire user group) that has upgraded to a newer trunking system. Cross communication is often required when handling emergency situations. Another case is the individual to individual commu- nication need where cross-communication between, for example, team leaders operating on the two sys- tem types is required in order to facilitate a more efficient crisis resolution.

  A method exists today that attempts to solve this problem. A device called a console (also called a control center) can be used to bridge audio between a trunking group and a conventional channel. This operation is called a console "patch". With this solution, communications activity that is detected for the trunking group is passed through the console device to a selected conventional channel where it is retransmitted. Also, for the opposite direction, whenever any activity is detected on the selected conventional channel, it is routed through the...