Browse Prior Art Database

IMPROVED DIFFERENT SYSTEM HANDOVER

IP.com Disclosure Number: IPCOM000007669D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-12
Document File: 5 page(s) / 238K

Publishing Venue

Motorola

Related People

Gary Grube: AUTHOR

Abstract

There are a growing number of legacy two-way wireless system types. Many of the systems are multi-site, and many of those include automatic handover services as the users move from site to site within the same system type. Most of these sys- tem infrastructures are single mode while many of the newer communication units are multi-mode to provide functionality as the user moves among var- ying system types. Users require geographic handover, no matter if it is site-to-site or system-to- system. System-to-system handover is provided when the systems are of the same type. System-to-system handover is not provided when the systems are not the same type.

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Page 1 of 5

M-ROLA Technical Developments

IMPROVED DIFFERENT SYSTEM HANDOVER

by Gary Grube

BACKGROUND

  There are a growing number of legacy two-way wireless system types. Many of the systems are multi-site, and many of those include automatic handover services as the users move from site to site within the same system type. Most of these sys- tem infrastructures are single mode while many of the newer communication units are multi-mode to provide functionality as the user moves among var- ying system types. Users require geographic handover, no matter if it is site-to-site or system-to- system. System-to-system handover is provided when the systems are of the same type. System-to-system handover is not provided when the systems are not the same type.

  See Figure 1. Current systems are built around one air-interface standard. System owners generally have not been interested in supporting more than one type, nor have they been interested in "interfacing" their system to another of a different type. Current systems and new systems such as APCO 25 and

TETRA contain an Inter System Interface (ISI) spec- ification. These specify interfacing to other sites and systems, of the same type, and include handover pro- cedures. They do not describe procedures to inter- face with a multitude of other system types. This is why the prior art does not solve the problem. Con- sole systems provide simple cross-system type patch, but without handover, i.e. they patch static users from one system type to another.

  Some dual mode cellular systems have both ana- log sites and digital sites. Many times the digital sites will "announce;' on a control channel, that the adjacent cell site is of the other mode type. This is a system that has one switch that knows how to control two mode type air interfaces. This will not solve the present problem since these dual mode switches control sites not other analog only switches and digital only switches. It is desired to simply (and cheaply) add equipment to bridge two existing sys- tems where there are two switches that only speak one language.

0 Mororola. 1°C. ,996 93 May 1996

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MOlVROLA Technical Developments

TYPE A/B TYPE A/B

MULTI-MODE COMM UNITS

NO HANDOVER!

Fig. 1 Prior Art

resources that talk the "B" air interface. The bridg- ing resources have the same coverage, and are positioned in between the system A and system B coverage areas. Themare actually two sets of resources for each mode type within the bridging area, i.e. two A channels and two B channels. This could be two adjacent cells or two adjacent sectors. The reason for at least two is to provide the handover controller with first hand knowledge of the direc- tion of travel of the roaming unit. For example, a roamer moves from a regular A cell to a A" sector and then to a A' sector, it is now determined that the unit is indeed moving towards the B system and the handover between modes can start.

SO...