Radio base station apparatus, mobile terminal apparatus and radio communication method

A mobile terminal apparatus comprising:

• a cyclic shift section configured to add phase rotation amounts to a plurality of subcarriers;
• and
• a transmission section configured to transmit to a radio base station an uplink control signal including a reference signal using the plurality of subcarriers to which the phase rotation amounts are added,
• wherein the phase rotation amounts are set to minimize the number of unit subcarriers for coherent averaging in association with the number of multiplexed users;
• and
• wherein the radio base station performs coherent averaging on the reference signal using the different number of unit subcarriers corresponding to the number of multiplexed users to demultiplex into a reference signal for each of the users.

A radio communication method comprising:

• in a mobile terminal apparatus, adding phase rotation amounts to a plurality of subcarriers;
• transmitting an uplink control signal including a reference signal and feedback control information using the plurality of subcarriers to which the phase rotation amounts are added;
• in a radio base station apparatus, receiving the uplink control signal;
• performing coherent averaging on the reference signal using the different number of unit subcarriers corresponding to the number of multiplexed users to demultiplex into a reference signal for each of the users;
• and
• estimating a channel variation using the demultiplexed reference signal,
• wherein the phase rotation amounts are set to minimize the number of unit subcarriers for coherent averaging in association with the number of multiplexed users.