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OPTIMAL DYNAMIC CHANNEL ALLOCATION THROUGH ISM BAND PROFILE CONSTRUCTION

IP.com Disclosure Number: IPCOM000008197D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-27
Document File: 3 page(s) / 156K

Publishing Venue

Motorola

Related People

Slim Souissi: AUTHOR

Abstract

We suggest the use of dynamic channel allocation for reverse paging in the ISM (Industrial Scientific and Medical) band. A method of dynami- cally allocating spread spectrum channels to a population of pagers within a given coverage zone is described. An accurate profile of the ISM band at the subject spread spectrum receiver location should be drawn and continuously updated. Band profile estimation are based on the radiometer shown in Figure 1. This energy detector consists of a bandpass filter (BPF) of center frequency f, and bandwidth W and a square law operation followed by a T-second integrator. The integrator is reset at the end of each successive T-second period. T is generally dictated by the dynamics of the ISM band. If the profile changes every T, second then the appropriate value of T would be T..

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@ M-LA Technical Developments

OPTIMAL DYNAMIC CHANNEL ALLOCATION THROUGH ISM BAND PROFILE CONSTRUCTION

by Slim Souissi

  We suggest the use of dynamic channel allocation for reverse paging in the ISM (Industrial Scientific and Medical) band. A method of dynami- cally allocating spread spectrum channels to a population of pagers within a given coverage zone is described. An accurate profile of the ISM band at the subject spread spectrum receiver location should be drawn and continuously updated. Band profile estimation are based on the radiometer shown in Figure 1. This energy detector consists of a bandpass filter (BPF) of center frequency f, and bandwidth W and a square law operation followed by a T-second integrator. The integrator is reset at the end of each successive T-second period. T is generally dictated by the dynamics of the ISM band. If the profile changes every T, second then the appropriate value of T would be T..

1. ISM BAND PROFILE CONSTRUCTION

   The user has to specify the profile resolution (equal to the PBF bandwidth W) as well as the spread spectrum channel bandwidth (W,,). Once the least noisy channel of bandwidth W,. identified, the receiver informs the RF controller about the start frequency of the subject channel. The RF controller processes the information provided by all the spread spectrum receivers within a given zone and decides which channel to assign to every group of pagers. There are several ways to scan the entire ISM band and identify the best existent channel:

  Radiometer bank scanner: As shown by Figure 2, every radiometer (i) measures the energy within a frequency band W at center frequency f,. The N different measurements are collected and used to construct the profile of the band. The lower W, the higher N and the better the profile resolution. A tradeoff between number of radiometers and the profile resolution should be made. This parallel

implementation of the scanner provides very fast estimations of the band profile at the expense of considerable amount of hardware.

  Hopping radiometer scanner: Provided that the time variations of the ISM band profile are slow compared to the profile construction time, an attractive implementation of the scanner could be a frequency hopping radiometer. That is, a single radiometer is used to scan the entire band. The lilter center frequency hops every Td4 seconds (dwell time) from f, to fl, . . . to f,. Every hopping cycle results in a profile drawing. The dwell time and the band resolution should be specified by the user. Their values are related to the dynamics of the ISM band and to the spread spectrum system in use.

  Hybrid radiometer bank/hopping radiometer scanner: Another way to scan the ISM band is to use a hybrid implementation of the two previously described scanners: Multiple radiometers hopping around the entire band.

2. OPTIMAL CHANNEL SELECTION

  Once the band is scanned several times, the receiver constructs an average profile. The average profile i...