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LOAD BALANCING OF SUBSCRIBERS ON A WIDE AREA MULTI-SITE SYSTEM

IP.com Disclosure Number: IPCOM000008048D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-15
Document File: 2 page(s) / 110K

Publishing Venue

Motorola

Related People

Steve Norwood: AUTHOR [+3]

Abstract

In a wide area private trunked system, such as a Motorola SmartZone system, some customers have chosen, due to jurisdictional control reasons, to have sites with large amounts, and at times, com- plete, overlap. These sites with large overlap have differing amounts of resources available and are intended for use by different user groups, An exam- ple of this could be a wide area system where there is a high density (i.e. many channels) simulcast site for police patrol units that completely covers a low density site for a prison. The customer intends for the correct users to use the correct system during steady state condition. This can be accomplished using the existing technology such as the preferred site algorithm used in the subscriber unit.

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MOTOROLA Technical Developments

LOAD BALANCING OF SUBSCRIBERS ON A WIDE AREA MULTI-SITE SYSTEM

by Steve Norwood, Jim Edkins, and Dan McDonald

BACKGROUND

  In a wide area private trunked system, such as a Motorola SmartZone system, some customers have chosen, due to jurisdictional control reasons, to have sites with large amounts, and at times, com- plete, overlap. These sites with large overlap have differing amounts of resources available and are intended for use by different user groups, An exam- ple of this could be a wide area system where there is a high density (i.e. many channels) simulcast site for police patrol units that completely covers a low density site for a prison. The customer intends for the correct users to use the correct system during steady state condition. This can be accomplished using the existing technology such as the preferred site algorithm used in the subscriber unit.

PROBLEM

  The problem, however, is when a failure occurs, When a failure such as site trunking, all subscriber units may determine, at virtually the same time, that they must leave the failed site and move to a wide area site. This causes loading problems both on the control channel (due to subscriber units registering on the new site) and a lack of voice resources due to the unexpected influx of units. This has the poten- tial for causing a site to be overloaded to the point

that system operation is severely hampered. Since a site could not be correctly loaded, the incorrect dis- tribution of subscriber units could result in a large number of lengthy busies. This operation could result in customer dissatisfication.

SOLUTION

  This idea is to broadcast information at each site about the status of adjacent sites. More specifically, this idea is to send out adjacent site information based on (1) talkgroups, (2) groups of talkgroups,
(3) or both, instead of broadcasting adjacent site

information to all subscriber units as is done in many of today's wide area systems. This idea pro- vides a mechanism to effectively control the move- ment of subscriber units in the system. This inven- tion solves all of the loading problems as follows:

  1. When a failure occurs, the system can inform small groups at a time (perhaps on a group priority basis) of the failure condition (such as a site going into site trunking) via the adjacent site information signaling. This allows the customer to evenly move groups of units to non-failed sites thus pr...