To alleviate processing load on a communication apparatus (mobile station) during data transmission using the shared channels, the radio communication apparatus comprises a receiving unit (21) adapted for intermittent reception and arranged to determine whether the data received via the shared channels is intended for its own station or not. The communication apparatus further comprises a transmitting unit (23) arranged for intermittent transmission of information which influences the transmission format of the data. This intermittent transmission takes place a predetermined time before the intermittent reception timing of the receiving unit.