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Mobile radio communication system

  • US 5,117,502 A
  • Filed: 03/15/1991
  • Issued: 05/26/1992
  • Est. Priority Date: 03/19/1990
  • Status: Expired due to Term
First Claim
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1. A mobile radio communication system comprising:

  • a control station which is provided with respect to a control zone, said control zone being made up of a plurality of radio zones;

    a base station which is provided with respect to each of the radio zones; and

    a mobile station which is movable within the control zone,said mobile station including first means for constantly monitoring a quality of a radio line between said mobile station and a first base station with which said mobile station is presently communicating, said first base station being provided with respect to a first radio zone, second means coupled to said first means for detecting a deterioration of the quality of the radio line between said mobile station and said first base station outside a tolerable range, third means coupled to said first means for successively detecting field intensities of signals received from the base stations neighboring said first base station using a free time slot which is unused by said mobile station for communication and for determining a maximum field intensity, fourth means coupled to said third means for supplying to said first base station predetermined information related to a second base station from which the signal with the maximum field intensity is received so as to make a handover request, and fifth means for ending the communication with said first base station in response to a handover message, said second base station being provided with respect to a second radio zone which is different from said first radio zone,said first base station including means for supplying a handover request message to said control station in response to the handover request from said mobile station,said control station including means for carrying out a handover process in response to the handover request message, said handover process including selecting a new communication channel with which said mobile station is to communicate with said second base station when said mobile station moves from said first radio zone to said second radio zone, and notifying the handover message and the new communication channel to said mobile station and said first and second base stations, so that said mobile station ends the communication with said first base station in response to the handover message and starts a communication with said second base station using the new communication channel.

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