Patent ID: 8275565

Claim:
A radio communication apparatus used in a mobile communication system, comprising: a unit configured to receive a user data channel including a sequence number and determining a system frame number, a process number, and new packet identification information; a unit configured to detect whether a received first packet includes an error and transmitting a report of the detected result indicating an affirmative or a negative result to a transmitter side; a unit configured to detect whether a control channel has not been correctly received in the past based on the process number and the new packet identification information of a second packet transmitted after the first packet; a unit configured to generate an indicator consisting of the system frame number corresponding to a latest control channel having been correctly received; and a unit configured to report the system frame number of the indicator at which the second packet is transmitted, so that the transmitter side specifies the sequence number of a packet to be re-transmitted based on the system frame number, the packet being transmitted to the radio communication apparatus by a preceding system frame number preceding the reported system frame number at which the second packet is transmitted, wherein a transmission timing at which the control channel has not been correctly received is identified based on the preceding system frame number.