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Method and system for mobile controlled handoff and link maintenance in spread spectrum communication

  • US 6,088,590 A
  • Filed: 08/01/1994
  • Issued: 07/11/2000
  • Est. Priority Date: 11/01/1993
  • Status: Expired due to Term
First Claim
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1. A method for handoff in a time division multiple access communication system, comprising the steps ofcommunicating between a user station and a first base station in a first time slot of a time frame;

  • monitoring, at said user station in communication with said first base station, a received signal quality of messages transmitted in said first time slot, and deriving a link quality measurement thereby;

    comparing said link quality measurement against a threshold level;

    comparing said link quality measurement against a second threshold level higher than said first threshold level and, when said link quality measurement falls below said second threshold level, monitoring at said user station a received signal quality from messages transmitted by at least one other base station, said at least one other base station including said terminal;

    when said link quality measurement falls below said threshold level, initiating at said user station a handoff procedure to a terminal base station, said handoff procedure comprising the steps ofreceiving at said user station a general polling message from said terminal base station in a second time slot;

    transmitting, in said second time slot and in response to said general polling message, a general polling response message from said user station to said terminal base station;

    receiving said general polling response message at said terminal base station;

    transmitting, in said second time slot and in response to said general polling response message, a specific polling message from said terminal base station to said user station, said specific polling message comprising a user station identifier;

    receiving said specific polling message at said user station;

    transmitting, in said second time slot, a handoff signaling message from said user station to said terminal base station;

    receiving said handoff signaling message at said terminal base station;

    transmitting, in said second time slot and in response to said handoff signaling message, a handoff acknowledgment signal from said terminal base station to said user station; and

    receiving said handoff acknowledgment signal at said user station.

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