Radio communication base station apparatus and method for controlling transmission power of sounding reference signal

A radio communication base station apparatus, comprising:

• a transmitter, which, in operation, transmits control information including a transmission request for an aperiodic sounding reference signal (A-SRS) and including a transmission power control command (TPC command) for transmission of the A-SRS;
• and
• a receiver, which, in operation, receives the A-SRS at a controlled transmission power value, wherein
• the controlled transmission power value of the A-SRS is based on a first accumulation value of the TPC command updated with the transmitted TPC command, wherein
• an initial value of the first accumulation value is set to zero, in a first case in which a radio resource control (RRC) control signal more frequently updates a transmission power parameter associated with the TPC command than a defined frequency threshold, and
• the initial value of the first accumulation value is set to a PUSCH (Physical Uplink Shared Channel) TPC command accumulation value, in a second case in which the RRC control signal less frequently updates the transmission power parameter associated with the TPC command than the defined frequency threshold.