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Method and apparatus for generating a simulcast response from a plurality of portable communication units

  • US 5,530,437 A
  • Filed: 08/27/1993
  • Issued: 06/25/1996
  • Est. Priority Date: 08/27/1993
  • Status: Expired due to Fees
First Claim
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1. A method of determining identities of respondents to a poll transmitted by a fixed communication unit in a radio communication system including a central controller, a plurality of portable communication units, and the fixed communication unit, wherein the fixed communication unit comprises a transmitter and a plurality of geographically disperse receivers, the method comprising the steps of:

  • programming a plurality of bit patterns within a subset of the plurality of portable communication unit for identifying individual portable communication units of said subset, each bit pattern corresponding uniquely to a portable communication unit and chosen such that when a group of at least two of the portable communication units are received simultaneously by a receiver of the plurality of receivers, thereby producing an interference bit pattern in the receiver, the interference bit pattern provides a non-zero probability of correctly identifying at least a portion of said group, and a substantially zero probability of erroneously identifying a portable communication unit not in said group;

    transmitting thereafter from said subset a plurality of simultaneous, co-channel responses to the poll, a response comprising one of said plurality of bit patterns transmitted without modification, exactly as programmed; and

    determining therefrom identities of received portable communication units of said subset by the interference bit patterns received by the plurality of receivers.

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