Method for transmitting uplink data during handoff

A method for transmitting uplink data in a soft handoff system, in which a mobile station is simultaneously connected with a plurality of base transceiver systems under a control of a base station controller, the method comprising the steps of:

• designating, by the mobile station, a main base transceiver system and a sub-transceiver system among the base transceiver systems;
• transmitting, by the mobile station, first and second uplink signals to the main base transceiver system and the sub-base transceiver system, respectively;
• transmitting, by the sub-base transceiver system, the second uplink signals to the main base transceiver system;
• and
• diversity-combining, by the main base transceiver system, the first uplink signal with the second uplink signal,
• wherein if the mobile station supports partial incremental redundancy transmission, the first uplink signal includes a systematic bit and a first parity bit and the second uplink signal includes the systematic bit and a second parity bit, and wherein diversity combining the first uplink signal with the second uplink signal comprises;
• extracting, by the sub-base transceiver system, a first soft bit string by demodulating the second uplink signal;
• transmitting, by the sub-base transceiver system, the first soft bit string to the main base transceiver system;
• extracting, by the main base transceiver system, a second soft bit string by demodulating the first uplink signal;
• and
• diversity-combining by the main base transceiver system, the soft bit string with the second soft bit string.