A system comprising a base station and a mobile station, wherein: the base station comprises: an assigning unit configured to assign a sequence in one of multiple groups, which contain sequences generated from a plurality of Zadoff-Chu, ZC, sequences and cyclic shifts as reference signals, to the mobile station; and a transmitting unit configured to transmit, to the mobile station, control information related to the assigned sequence, and the mobile station comprises: a receiving unit configured to receive the control information; a determining unit configured to determine a ZC sequence and a cyclic shift in said one of the multiple groups based on the control information; a generating unit configured to generate a reference signal using the determined ZC sequence and the determined cyclic shift; and a transmitting unit configured to transmit the reference signal generated using the determined ZC sequence and the determined cyclic shift, wherein the sequences are grouped, for one transmission bandwidth for the reference signal, into the multiple groups, each of which contains a predefined number of the sequence(s) which varies according to the transmission bandwidth. the base station comprises: an assigning unit configured to assign a sequence in one of multiple groups, which contain sequences generated from a plurality of Zadoff-Chu, ZC, sequences and cyclic shifts as reference signals, to the mobile station; and a transmitting unit configured to transmit, to the mobile station, control information related to the assigned sequence, and an assigning unit configured to assign a sequence in one of multiple groups, which contain sequences generated from a plurality of Zadoff-Chu, ZC, sequences and cyclic shifts as reference signals, to the mobile station; and a transmitting unit configured to transmit, to the mobile station, control information related to the assigned sequence, and the mobile station comprises: a receiving unit configured to receive the control information; a determining unit configured to determine a ZC sequence and a cyclic shift in said one of the multiple groups based on the control information; a generating unit configured to generate a reference signal using the determined ZC sequence and the determined cyclic shift; and a transmitting unit configured to transmit the reference signal generated using the determined ZC sequence and the determined cyclic shift, wherein the sequences are grouped, for one transmission bandwidth for the reference signal, into the multiple groups, each of which contains a predefined number of the sequence(s) which varies according to the transmission bandwidth. a receiving unit configured to receive the control information; a determining unit configured to determine a ZC sequence and a cyclic shift in said one of the multiple groups based on the control information; a generating unit configured to generate a reference signal using the determined ZC sequence and the determined cyclic shift; and a transmitting unit configured to transmit the reference signal generated using the determined ZC sequence and the determined cyclic shift, wherein the sequences are grouped, for one transmission bandwidth for the reference signal, into the multiple groups, each of which contains a predefined number of the sequence(s) which varies according to the transmission bandwidth.