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Browse Prior Art Database

LOW DENSITY MULTI-SITE ROAMING

IP.com Disclosure Number: IPCOM000008498D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-18
Document File: 4 page(s) / 192K

Publishing Venue

Motorola

Related People

Keith Mulford: AUTHOR

Abstract

There is a market segment which require systems composed of a relatively small numbers of sites and which can be delivered a very low cost per communication resource. This need includes the requirement for significantly lower cost solutions to support the automatic roaming of subscribers as they move between sites. Current methods to addressing roaming, as implemented in Cellular and Private Mobile Radio, PMR, systems, SmartZone for example, are too complex and too costly to effectively address the grade of service needed by these smaller private system owners. The computers required to implement these roaming techniques for these larger systems are typically more expensive then the total market value of an entire radio system by these customers.

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MOTOROLA Technical Developments

LOW DENSITY MULTI-SITE ROAMING

by Keith Mulford

BACKGROUND

  There is a market segment which require systems composed of a relatively small numbers of sites and which can be delivered a very low cost per communication resource. This need includes the requirement for significantly lower cost solutions to support the automatic roaming of subscribers as they move between sites. Current methods to addressing roaming, as implemented in Cellular and Private Mobile Radio, PMR, systems, SmartZone for example, are too complex and too costly to effectively address the grade of service needed by these smaller private system owners. The computers required to implement these roaming techniques for these larger systems are typically more expensive then the total market value of an entire radio system by these customers.

LOW DENSITY ALTERNATIVE

  This solution applies to both distributed and centralized control configurations. In both cases, a plurality of subscribers are serviced by multiple RF coverage sites. Each of the subscriber units is assigned to a "Home" site which, based on typical travel patterns, provides a majority of its service. When the subscriber roams out of the coverage of its home site, it is provided communications services as follows:

1) For distributed control style systems, where the control function for call set up and roaming are distributed among multiple sites:

  Within a small multi-site system, when a subscriber roams outside of its "home" site and accesses a new site, it registers with the new site. Each site control function holds a list of subscribers who are assigned to the site as a home site. If a registering subscriber is not on the "home site" list, the visited site control function notifies all sites

within the system with a broadcast message containing the identity (individual and group) of the roaming subscriber and the fact that it has registered at a non-home site. The distributed controllers at other sites maintain a simple list containing the identities of subscribers (individual and group) who are not in their home sites, based on receiving of broadcast messages from other sites. When a call is placed to a single subscriber the site controller receiving the request checks to see if the subscriber is on its "not-at-home" list (i.e. the unit has roamed away from its home and is somewhere in the system) and checks to see the unit is not on its "home site" (i.e. if it is not present on the "home list" it must be from a different home site). If the requested subscriber is on the "not-at-home list" or it is not on the "home list," the originating site controller broadcasts the subscriber's ID and the message content to all sites, thus "flooding" the system. In the case of a multi-unit or group call the originating controller looks at the group side of the list and repeats the same process if any one unit affiliated with the group fits the criteria above.

  The method by which the ot...