Radio communication system, radio communication apparatus, and radio communication method

Abstract

A radio communication apparatus specifies a radio resource area in which a radio communication apparatus searches for a control signal, on the basis of information about the use of a plurality of frequency bands. Then, the radio communication apparatus transmits a control signal addressed to the radio communication apparatus in the specified radio resource area. The radio communication apparatus calculates the specified radio resource area on the basis of the information about the use of the plurality of frequency bands. Then, the radio communication apparatus searches signals in the calculated radio resource area, out of signals received from the radio communication apparatus, and thereby detects the control signal addressed to the radio communication apparatus.

What is claimed is: 
     
         1 . A radio communication system comprising:
 a first radio communication apparatus and a second radio communication apparatus that communicate by radio with each other using a plurality of frequency bands;   wherein the first radio communication apparatus includes
 a control unit configured to specify a radio resource area in which the second radio communication apparatus searches for a control signal, on the basis of a carrier indicator indicating a component carrier used for communication in the plurality of frequency bands; and 
 a transmitting unit configured to transmit a control signal addressed to the second radio communication apparatus, in the radio resource area specified by the control unit; and 
   wherein the second radio communication apparatus includes
 a calculating unit configured to calculate the specified radio resource area, on the basis of the carrier indicator indicating a component carrier used for communication in the plurality of frequency bands; and 
 a detecting unit configured to search signals in the radio resource area calculated by the calculating unit, out of signals received from the first radio communication apparatus, so as to detect the control signal addressed to the second radio communication apparatus. 
   
     
     
         2 . The radio communication system according to  claim 1 , wherein the carrier indicator indicating a component carrier used for communication in the plurality of frequency bands includes the number of frequency bands to be used for data communication by the second radio communication apparatus. 
     
     
         3 . The radio communication system according to  claim 2 , wherein the control unit determines a size of the radio resource area on the basis of the number of frequency bands to be used for the data communication. 
     
     
         4 . The radio communication system according to  claim 2 , wherein the control unit determines a size of the radio resource area on the basis of the difference between the number of frequency bands to be used for the data communication and the number of frequency bands to be used for transmission of the control signal addressed to the second radio communication apparatus. 
     
     
         5 . The radio communication system according to  claim 2 , wherein the control unit determines a location of the radio resource area on the basis of the number of frequency bands to be used for the data communication. 
     
     
         6 . The radio communication system according to  claim 1 ,
 wherein the control unit further specifies another radio resource area to be commonly searched by a plurality of radio communication apparatuses including the second radio communication apparatus; and   wherein the control unit determines a location of the radio resource area on the basis of a location of the specified other radio resource area in addition to the carrier indicator indicating a component carrier used for communication in the plurality of frequency bands.   
     
     
         7 . The radio communication system according to  claim 1 , wherein the carrier indicator indicating a component carrier used for communication in the plurality of frequency bands includes information indicating a frequency band to which the radio resource area is set. 
     
     
         8 . The radio communication system according to  claim 7 , wherein the control unit changes a location of the radio resource area in accordance with the frequency band to which the radio resource area is set. 
     
     
         9 . The radio communication system according to  claim 7 , wherein the information indicating a frequency band to which the radio resource area is set is included in a control signal transmitted in the radio resource area. 
     
     
         10 . A radio communication apparatus that communicates by radio with another radio communication apparatus using a plurality of frequency bands, the radio communication apparatus comprising:
 a control unit configured to specify a radio resource area in which said another radio communication apparatus searches for a control signal, on the basis of a carrier indicator indicating a component carrier used for communication in the plurality of frequency bands; and   a transmitting unit configured to transmit a control signal addressed to said another radio communication apparatus, in the radio resource area specified by the control unit.   
     
     
         11 . A radio communication apparatus that communicates by radio with another radio communication apparatus using a plurality of frequency bands, the radio communication apparatus comprising:
 a calculating unit configured to calculate a radio resource area to be used for transmission of a control signal addressed to the radio communication apparatus, on the basis of a carrier indicator indicating a component carrier used for communication in the plurality of frequency bands; and   a detecting unit configured to search signals in the radio resource area calculated by the calculating unit, out of signals received from said another radio communication apparatus, so as to detect the control signal addressed to the radio communication apparatus.   
     
     
         12 . A radio communication method that causes a first radio communication apparatus and a second radio communication apparatus to communicate by radio with each other using a plurality of frequency bands, the method comprising:
 specifying, by the first radio communication apparatus, a radio resource area in which the second radio communication apparatus searches for a control signal, on the basis of a carrier indicator indicating a component carrier used for communication in the plurality of frequency bands;   transmitting, by the first radio communication apparatus, a control signal addressed to the second radio communication apparatus, in the specified radio resource area;   calculating, by the second radio communication apparatus, the specified radio resource area, on the basis of the carrier indicator indicating a component carrier used for communication in the plurality of frequency bands; and   searching, by the second radio communication apparatus, signals in the calculated radio resource area, out of signals received from the first radio communication apparatus, so as to detect the control signal addressed to the second radio communication apparatus.