Base station, mobile station, radio communication system, and communication control method

Abstract

One of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to a base station and a different one of the sequence groups is assigned to a neighboring cell. The base station includes a scheduler configured to allocate radio resources; a reporting unit configured to report the allocated radio resources and a cyclic shift amount to a mobile station; and a demodulating unit configured to demodulate a signal received from the mobile station based on one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount. Cell reuse is applied to the reference signal sequences to be transmitted using one resource unit, and sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.

1 . A base station for communicating with a mobile station transmitting an uplink signal according to a single-carrier scheme, wherein one of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to the base station, a different one of the sequence groups is assigned to a neighboring cell, and the mobile station transmits the uplink signal including one of the reference signal sequences specified by the one of the sequence groups assigned to the base station, the base station comprising:
 a scheduler configured to allocate radio resources such that one or more resource units are allocated to the mobile station for communication;   a reporting unit configured to report the allocated radio resources and a cyclic shift amount to the mobile station; and   a demodulating unit configured to demodulate the uplink signal received from the mobile station based on the one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount, wherein   cell reuse is applied to the reference signal sequences to be transmitted using one resource unit; and   sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.   
     
     
         2 . The base station as claimed in  claim 1 , further comprising:
 a broadcasting unit configured to broadcast the one of the sequence groups assigned to the base station to the mobile station.   
     
     
         3 . The base station as claimed in  claim 1 , wherein
 one of the reference signal sequences to be transmitted using one resource unit is statically assigned to the base station;   the reference signal sequences to be transmitted using the bandwidth greater than one resource unit are divided into sequence groups the number of which equals a total number of the reference signal sequences to be transmitted using one resource unit; and   the reference signal sequences in each one of the sequence groups are assigned to different subframes.   
     
     
         4 . The base station as claimed in  claim 3 , wherein
 when one resource unit is a minimum bandwidth W 1 , a number of the reference signal sequences using the minimum bandwidth W 1  is N 1 , and a number of the reference signal sequences using a bandwidth W x  that is X times greater than the minimum bandwidth W 1  is XN 1 , N 1  sequence groups are generated; and   a kth sequence group (k is an integer greater than or equal to 1 and less than or equal to N 1 ) includes (W x /W 1 ) reference signal sequences with sequence numbers k, k+N 1 , . . . , and k+(W x /W 1 )N 1  for the bandwidth W x .   
     
     
         5 . The base station as claimed in  claim 4 , wherein one of the N 1  sequence groups is assigned to the base station. 
     
     
         6 . The base station as claimed in  claim 4 , wherein when a radio resource bandwidth allocated to the mobile station is W x , the sequence hopping is performed using the (W x /W 1 ) reference signal sequences with sequence numbers k, k+N 1 , . . . , and k+(W x /W 1 )N 1 . 
     
     
         7 . The base station as claimed in  claim 6 , wherein one or more hopping patterns are predetermined for each of the N 1  sequence groups. 
     
     
         8 . The base station as claimed in  claim 1 , wherein the reference signal sequences are CAZAC sequences. 
     
     
         9 . A mobile station transmitting an uplink signal according to a single-carrier scheme, comprising:
 a storage unit configured to store sequence groups each specifying reference signal sequences for respective radio resource bandwidths;   a transmitting unit configured to determine one of the reference signal sequences corresponding to one of the radio resource bandwidths based on radio resources allocated by a base station, to shift the determined one of the reference signal sequences by a cyclic shift amount assigned by the base station, and to transmit the uplink signal including the shifted one of the reference signal sequences, wherein   cell reuse is applied to the reference signal sequences to be transmitted using one resource unit; and   sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.   
     
     
         10 . The mobile station as claimed in  claim 9 , wherein
 one of the reference signal sequences to be transmitted using one resource unit is statically assigned to the base station;   the reference signal sequences to be transmitted using the bandwidth greater than one resource unit are divided into sequence groups the number of which equals a total number of the reference signal sequences to be transmitted using one resource unit; and   the reference signal sequences in each one of the sequence groups are assigned to different subframes.   
     
     
         11 . The mobile station as claimed in  claim 10 , wherein one or more hopping patterns are predetermined for each of the sequence groups. 
     
     
         12 . The mobile station as claimed in  claim 9 , wherein
 the mobile station includes multiple antennas; and   the transmitting unit is configured to use the same one of the reference signal sequences for two reference signals in a subframe.   
     
     
         13 . The mobile station as claimed in  claim 9 , wherein the reference signal sequences are CAZAC sequences. 
     
     
         14 . A radio communication system, comprising:
 a mobile station configured to transmit an uplink signal according to a single-carrier scheme; and   a base station configured to communicate with the mobile station, wherein   one of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to the base station;   a different one of the sequence groups is assigned to a neighboring cell;   the mobile station is configured to transmit the uplink signal including one of the reference signal sequences specified by one of the sequence groups assigned to the base station;   the base station includes   a scheduler configured to allocate radio resources such that one or more resource units are allocated to the mobile station for communication,   a reporting unit configured to report the allocated radio resources and a cyclic shift amount to the mobile station, and   a demodulating unit configured to demodulate the uplink signal received from the mobile station based on the one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount;   the mobile station includes   a storage unit configured to store the sequence groups, and   a transmitting unit configured to determine the one of the reference signal sequences corresponding to the one of the radio resource bandwidths based on the radio resources allocated by the base station, to shift the determined one of the reference signal sequences by the cyclic shift amount reported by the base station, and to transmit the uplink signal including the shifted one of the reference signal sequences;   cell reuse is applied to the reference signal sequences to be transmitted using one resource unit; and   sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.   
     
     
         15 . A communication control method used in a radio communication system including a mobile station transmitting an uplink signal according to a single-carrier scheme and a base station communicating with the mobile station, wherein one of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to the base station and a different one of the sequence groups is assigned to a neighboring cell, the method comprising:
 a radio resource allocation step, performed by the base station, of allocating radio resources such that one or more resource units are allocated to the mobile station for communication;   a reporting step, performed by the base station, of reporting the allocated radio resources and a cyclic shift amount to the mobile station;   a transmitting step, performed by the mobile station, of transmitting the uplink signal based on the radio resources and the cyclic shift amount reported by the base station; and   a demodulating step, performed by the base station, of demodulating the uplink signal received from the mobile station based on one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount, wherein   cell reuse is applied to the reference signal sequences to be transmitted using one resource unit; and   sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.   
     
     
         16 . The mobile station as claimed in  claim 10 , wherein
 the mobile station includes multiple antennas; and   the transmitting unit is configured to use the same one of the reference signal sequences for two reference signals in a subframe.   
     
     
         17 . The mobile station as claimed in  claim 11 , wherein
 the mobile station includes multiple antennas; and   the transmitting unit is configured to use the same one of the reference signal sequences for two reference signals in a subframe.