Patent ID: 8359032

Claim:
A user data transmission method for transmitting uplink user data from a mobile station via an enhanced dedicated physical data channel, comprising: determining, at a radio network controller, that the mobile station transmitting the enhanced dedicated physical data channel to only a first cell shifts to a soft handover state and transmits the enhanced dedicated physical data channel to the first cell and a second cell; notifying, from the radio network controller to the mobile station, transmission acknowledgement channel decoding information for decoding a transmission acknowledgement channel for the uplink user data to be transmitted by the second cell, based on the determination made at the radio network controller and before the mobile station shifts to the soft handover state; decoding, at the mobile station, the transmission acknowledgement channel for the uplink user data to be transmitted from the second cell, based on the transmission acknowledgement channel decoding information; and performing, at the mobile station, a retransmission control of the uplink user data toward the second cell based on the decoded transmission acknowledgement channel for the uplink user data, the transmission acknowledgement channel decoding information is included in the soft handover setting request transmitted from the radio network controller to the mobile station when the radio network controller determines that the mobile station shifts to the soft handover state.