Browse Prior Art Database

VARIABLE BANDWIDTH RSSI SCANNING

IP.com Disclosure Number: IPCOM000007759D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-19
Document File: 3 page(s) / 114K

Publishing Venue

Motorola

Related People

Bill Mitchell: AUTHOR

Abstract

In radio systems supporting a mobile and/or port- able subscriber base and using multiple RF chan- nels, there arises a need for subscribers to scan for a new channel upon power-up and upon channel loss. Oflentimes, this scanning can be planned intelligently by using information about available RF channels either broadcast on well-known control channels or inferred by the subscriber unit from information gathered during past usage.

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M-LA Technical Developments

VARIABLE BANDWIDTH RSSI SCANNING

by Bill Mitchell

programmable radio circuitry (e.g., the Motorola Telepoint Systems Division Zif/Syn chip). RF bandwidth is thereby becoming a controllable parameter.

  Having RF bandwidth as a controllable parame- ter could be used to the subscriber unit's advantage in scanning for a channel. For example, subscriber units needing to locate a new channel with zero information could follow a procedure something like the following:

THE PROBLEM

  In radio systems supporting a mobile and/or port- able subscriber base and using multiple RF chan- nels, there arises a need for subscribers to scan for a new channel upon power-up and upon channel loss. Oflentimes, this scanning can be planned intelligently by using information about available RF channels either broadcast on well-known control channels or inferred by the subscriber unit from information gathered during past usage.

  Inferred information is likely at least partially incorrect or outdated, and may not be available at all. Because of this, it is sometimes necessary for subscriber units to scan for an available RF channel starting with zero information. When the number of candidate channels is large, channel scanning can take some considerable time. CDPD subscriber units, for example, have over 800 candidate channels to scan.

  Given the somewhat generous presumption that a subscriber unit is able to tune to and evaluate a channel in 50 ms, a brute-force complete scan of 800 candidate channels would require 40 seconds to complete. Not only is 40 seconds a long time in human terms but, additionally, information acquired at the beginning of the scan is likely to be outdated by the time the scan is completed.

Perform a pre-scan with a widened RF bandwidth to pre-qualify groups of channels by determining an overall RSSI value for each channel group.

Order the pre-qualified cha...