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VARIABLE DYNAMIC RANDOM HOLDOFF FOR AFFILIATIONS

IP.com Disclosure Number: IPCOM000008004D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-10
Document File: 3 page(s) / 122K

Publishing Venue

Motorola

Related People

Richard Svienty: AUTHOR [+3]

Abstract

In multi-site systems, when a site goes down (e.g., due to failure), those radios affiliated with the site re-affiliate with a neighboring site. Because all the radios affiliated with the failed site will attempt to re-affiliate with a neighboring site at about the same time, the neighboring sites may become flood- ed and the system may become unusable. A typical system can affdiate about two users per second, and if a large site is involved, thousands of users may need to re-affiliate. Consequently, it will take a long time to re-affiliate some users, and in the mean time, no one can use the system until the re-afftlia- tions are all handled. A similar problem results when a normally heavily-loaded site comes back on line, and users try to re-affiliate with the site due to site preferences, available resources, etc.

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MOTOROLA Technical Developments

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VARIABLE DYNAMIC RANDOM HOLDOFF FOR AFFILIATIONS

by Richard Svienty, Gary Gutknecht and Yogesh Gaur

INTRODUCTION:

In multi-site systems, when a site goes down
(e.g., due to failure), those radios affiliated with the site re-affiliate with a neighboring site. Because all the radios affiliated with the failed site will attempt to re-affiliate with a neighboring site at about the same time, the neighboring sites may become flood- ed and the system may become unusable. A typical system can affdiate about two users per second, and if a large site is involved, thousands of users may need to re-affiliate. Consequently, it will take a long time to re-affiliate some users, and in the mean time, no one can use the system until the re-afftlia- tions are all handled. A similar problem results when a normally heavily-loaded site comes back on line, and users try to re-affiliate with the site due to site preferences, available resources, etc.

PRIOR ART:

  Currently, a radio must detect that a site goes down, and randomly selects one of many random delay times, between 0 and 255 seconds. This solu- tion only handles about 500 radios, but does not handle the problem when the radios come back to the site after the site returns to service.

INVENTION DESCRIPTION:

  Each site periodically transmits an OSW for itself (as a home site) and for each adjacent site. These OSW's contain the site number and could be modified to include a maximum random holdoff time. The maximum random holdoff time for a home site is based on the number of radios current- ly affiliated with the site. The maximum random

holdoff time for an adjacent site is based on the number of radios the adjacent site expects to re- affiliate (e.g., after a failure has occurred and the site has recovered, a large number of radios would be expected to re-affiliate). When no loading is pre- sent at an adjacent site, a lower number is sent as the maximum time. When heavy loading is present, a very high number is sent as the maximum time.

  After receiving the maximum holdoff time OSWs, the radios then calculate their holdoff time as a random percentage of the maximum holdoff time for each site switch. When switching due to a home site failure, a radio affiliated with that home site uses the maximum random holdoff time from that home site to re-affiliate with another site. In a normal handoff to an adjacent site (i.e....