Mobile station, a mobile radio communication system, and a mobile radio communication method

Abstract

In a mobile radio communication method in which a mobile station moves among a plurality of base stations at high speed, in order to solve a problem of increase in the amount of operation and its related increase in the amount of power consumption and heat emission which is resulted for maintaining good communication quality of communication by the mobile station which moves at high speed to the direction for approaching the base station or moving away from it, it provides detecting means for detecting changes in relative positions to a plurality of base stations, and selecting means for selecting an uplink signal reception base station which receives an uplink signal and selecting one or plural base stations, fluctuation of increase and decrease of which of distance from own mobile station is an opposite manner compared with a case of the uplink signal receiving base station, based on changes in the relative positions detected by said detecting means as a downlink signal transmission base station which transmits a downlink signal.

1 . A mobile station, comprising:
 a selector for selecting an uplink signal reception base station which receives an uplink signal and selecting at least one downlink signal transmission base station which transmits a downlink signal to the mobile station and whose increase and decrease of a change in a distance to the mobile station is opposite to the uplink signal reception base station.   
     
     
         2 . The mobile station according to  claim 1 , wherein
 said selector selects said downlink signal transmission base station from among base stations which the mobile station is approaching or moving away from, and selects said uplink signal reception base station from among said base stations from which the mobile station is moving away from when said downlink signal transmission base station is selected from among said base stations which the mobile station is approaching, and selects said uplink signal reception base station from among said base stations from which the mobile station is approaching when said downlink signal transmission base station is selected from among said base stations which the mobile station is moving away from.   
     
     
         3 . The mobile station according to  claim 1 , further comprising:
 a first antenna having directivity in front of a moving direction; and   a second antenna having directivity behind the moving direction,   wherein one of the first antenna and second antenna receives the downlink signal and the other antenna transmits the uplink signal.   
     
     
         4 . The mobile station according to  claim 1 , further comprising:
 a frequency setter for setting a receiving frequency and a transmitting frequency so as to receive a downlink signal having a frequency used by said selected downlink signal transmission base station, and transmit an uplink signal having a frequency used by said selected uplink signal reception base station.   
     
     
         5 . The mobile station according to  claim 1 , further comprising:
 a code setter for setting a receiving signal code and a transmitting signal code so as to receive a downlink signal which is encoded by a code used by said selected downlink signal transmission base station, and transmit an uplink signal which is encoded by a code used by said selected uplink signal reception base station.   
     
     
         6 . The mobile station according to  claim 1 , further comprising:
 a circuit that changes a reference clock frequency in the mobile station so that the reference clock frequency follows a reference clock frequency superposed on the downlink signal, and generates the uplink signal based on the reference clock frequency.   
     
     
         7 . A mobile radio communication system including a plurality of base stations and a mobile station which communicates with each of the base stations, the system comprising:
 a selector for selecting an uplink signal reception base station which receives an uplink signal and selecting at least one downlink signal transmission base station which transmits a downlink signal to the mobile station and whose increase and decrease of a change in a distance to the mobile station is opposite to the uplink signal reception base station.   
     
     
         8 . The mobile radio communication system according to  claim 7 , wherein said selector selects said downlink signal transmission base station from among said base stations which the mobile station is approaching or moving away from, and selects said uplink signal reception base station from among said base stations from which the mobile station is moving away from when said downlink signal transmission base station is selected from among said base stations which the mobile station is approaching and selects said uplink signal reception base station from among said base stations from which the mobile station is approaching when said downlink signal transmission base station is selected from among said base stations which the mobile station is moving away from. 
     
     
         9 . The mobile radio communication system according to  claim 7 ,
 wherein said mobile station includes a first antenna having directivity in front of a moving direction, and a second antenna having directivity behind the moving direction,   wherein one of the first antenna and the second antenna receives the downlink signal and the other antenna transmits the uplink signal.   
     
     
         10 . The mobile radio communication system according to  claim 7 , said mobile station further comprising:
 a frequency setter for setting a receiving frequency and a transmitting frequency so as to receive a downlink signal having a frequency used by said selected downlink signal transmission base station, and transmit an uplink signal having a frequency used by said selected uplink signal reception base station.   
     
     
         11 . The mobile radio communication system according to  claim 7 , said mobile station further comprising:
 a code setter for setting a receiving signal code and a transmitting signal code so as to receive a downlink signal which is encoded by a code used by said selected downlink signal transmission base station, and transmit an uplink signal which is encoded by a code used by said selected uplink signal reception base station.   
     
     
         12 . The mobile radio communication system according to  claim 7 , further comprising:
 a circuit that changes a reference clock frequency in the mobile station so that the reference clock frequency follows a reference clock frequency superposed on the downlink signal, and generates the uplink signal based on the reference clock frequency.   
     
     
         13 . A mobile radio communication method performed by a mobile station, the method comprising:
 selecting an uplink signal reception base station which receives an uplink signal; and   selecting at least one downlink signal transmission base station which transmits a downlink signal to the mobile station and whose increase and decrease of a change in a distance to the mobile station is opposite to the uplink signal reception base station.   
     
     
         14 . The mobile radio communication method according to  claim 13 , further comprising:
 selecting said downlink signal transmission base station from among base stations which the mobile station is approaching or moving away from;   selecting said uplink signal reception base station from among said base stations from which the mobile station is moving away from when said downlink signal transmission base station is selected from among said base stations which the mobile station is approaching; and   selecting said uplink signal reception base station from among said base stations from which the mobile station is approaching when said downlink signal transmission base station is selected from among said base stations which the mobile station is moving away from.