A communication method for a radio communication system employing an enhanced uplink scheme includes the steps of determining a transmission power control bit for controlling transmission power of a downlink control channel; generating an uplink control signal including the transmission power control bit; and transmitting the uplink control signal to a base station. In the determining step, whether an indicator channel indicating acknowledgement or negative acknowledgement for an uplink data channel is receivable at a quality level better than a predetermined value is evaluated, and the transmission power control bit of the indicator channel is determined based on the evaluation result.