Patent ID: 7269390
Filing Date: 2007-09-11
Classification: H04W

Abstract:
1. A radio communications system comprising a base station and a plurality of mobile stations each configured to communicate with said base station, wherein: said base station comprises: a first radio wave receiving unit configured to receive a first radio wave transmitted by one of said mobile stations; an arrival direction detecting unit configured to detect an arrival direction of said first radio wave received; a second radio wave transmitting unit configured to transmit, when said first radio wave is received, a reply radio wave in response to said first radio wave, said reply radio wave configured to be transmitted in the arrival direction, and configured to transmit a second radio wave having a different frequency from a frequency of said first radio wave and said reply radio wave, said second radio wave configured to be transmitted in the arrival direction of said first radio wave detected; and said mobile stations each comprise: a first radio wave transmitting unit configured to transmit said first radio wave; a second radio wave receiving unit configured to receive said second radio wave; and a transmission control unit configured to stop, when said second radio wave is being received by said second radio wave receiving unit, the transmission of said first radio wave by controlling said first radio wave transmitting unit.