A mobile terminal determine a reference signal sequence number based on a sequence length and a first selection reference value used for a first communication system that is different from a second communication system adapting a 3GPP release 10 or earlier. The first selection reference value is obtained from a sequence group number assigned to the terminal and different from a second selection reference value used for the second communication system. The mobile terminal generates a reference signal based on the determined reference signal sequence number and transmits the generated reference signal.