Browse Prior Art Database

SITE BROADCAST RSSI THRESHOLDS

IP.com Disclosure Number: IPCOM000009633D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2002-Sep-05
Document File: 2 page(s) / 103K

Publishing Venue

Motorola

Related People

Steven E. Van Swol: AUTHOR [+3]

Abstract

In current trunked systems subscribers are pro- grammed with fmed received signal strength indica- tor (RSSI) thresholds. These thresholds are used in comparing the signal strength quality of current and adjacent sites. As systems grow in geography, this implementation does not allow for the thresholds to change relative to the various site topologies. For example, a system may have some sites with little coverage overlap and other sites with large areas of overlap.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 2

0 M M-LA Technical Developments

SITE BROADCAST RSSI THRESHOLDS

by Steven E. Van Swol, David A. Forseth and Gary P. Hunsberger

PROBLEM

  In current trunked systems subscribers are pro- grammed with fmed received signal strength indica- tor (RSSI) thresholds. These thresholds are used in comparing the signal strength quality of current and adjacent sites. As systems grow in geography, this implementation does not allow for the thresholds to change relative to the various site topologies. For example, a system may have some sites with little coverage overlap and other sites with large areas of overlap.

  The current implementation would not allow the radio to factor site overlap into roaming decisions. This forces the signal strength thresholds to be opti- mized for a given topology. This results in areas of excessive site switching or sub-optimal coverage.

SOLUTION

  The solution to this problem is to allow the sites to broadcast threshold level information to the radio for each adjacent site. In the two existing RSSI threshold mechanisms, this would either be a delta number to be used to adjust each of the levels for systems using codeplugt level comparisons or a sig- nal strength delta for systems using absolute differ- ence comparisons. Radios would use these new val- ues to determine the optimal roaming conditions for the current site. This allows roaming to be contig- ured on a per site basis rather than a per system basis.

   1, The codeplug is the poliion of the, dmaiber plugramming which is configured by the user. The cc&plug alows customers to cmdii sub SJxikr aperatio" to me.3 their specific needs. The codeplug contains ax- tml channel frequencies, channel frequencies, RSSI threshold options. cilmel names, etc.

IMPLEMENTATION EXAMPLE

  The following example will illustrate how the variable site RSSI threshold allows a subscriber radio to optimize roaming decisions based upon site geography. The example uses codeplug level com- parison as a basis for roaming decisions.

Site Site

A B

System 1

  System 1 has little overlap between sites A and B In this configuration it would be desirable if the subscriber unit switched from site A to site B once the signal strength from site B was larger than site
A. This is accomplished by compressing the RSSI levels making the two level di...