Method or HARQ acknowledgement transmission and transport block retransmission in a wireless communication system

1. A method of retransmitting transport blocks in a base station of a wireless communication system employing carrier aggregation, the method comprising:

mapping each of a plurality of transport blocks to each of a plurality of component carriers using a first mapping pattern;

transmitting the plurality of transport blocks to a mobile station;

recognizing whether the plurality of transport blocks are transmitted successfully; and

mapping each of the plurality of transport blocks to each of the plurality of component carriers using a second mapping pattern and retransmitting the plurality of transport blocks to the mobile station, when the plurality of transport blocks are not transmitted successfully,

wherein the first mapping pattern is different from the second mapping pattern,

wherein the retransmitting includes transmitting control information for each of the plurality of transport blocks to the mobile station,

the control information including a HARQ (hybrid automatic repeat request) swap indicator which indicates that a different mapping pattern from the first mapping pattern is used,

wherein the control information includes a carrier selection bit indicating which component carrier a specific transmission block is transmitted through, when a number of the plurality of component carriers is greater than 3,

wherein the control information further includes NDI (new data indicator) for determining, by the mobile station, a HARQ process ID, and

wherein the second mapping pattern is a pattern generated by cyclic-shifting the first mapping pattern by a specific component carrier number based on a number of retransmission attempts.

2. The method according to claim 1 , wherein the step of transmitting includes mapping two or more transport blocks to each of the plurality of component carriers using a third mapping pattern and the step of retransmitting includes mapping the two or more transport blocks to each of the plurality of component carriers using the third mapping pattern.

3. The method according to claim 1 , wherein the step of transmitting includes mapping two or more transport blocks to each of the plurality of component carriers using a third mapping pattern and the step of retransmitting includes mapping the two or more transport blocks to each of the plurality of component carriers using a forth mapping pattern.

4. The method according to claim 1 , wherein the step of recognizing includes recognizing that the plurality of transport blocks is not transmitted successfully by receiving negative acknowledgement (NACK).

5. The method according to claim 1 , wherein the step of recognizing includes recognizing that the plurality of transport blocks is not transmitted successfully by expiring a timer without receiving acknowledgement (ACK), wherein the timer is started immediately after transmitting the plurality of transport blocks.

6. A method of transmitting HARQ (hybrid automatic repeat request) acknowledgement in a receiver of a wireless communication system employing carrier aggregation, the method comprising:

receiving data transmitted in initial transmission and retransmission, through a plurality of component carriers from a transmitter; and

transmitting a plurality of HARQ acknowledgements for the data to the transmitter via an uplink control channel,

wherein mapping patterns for the initial transmission and retransmission are different from each other when a HARQ swap indicator received in retransmission indicates a HARQ swap occurrence,

wherein the uplink control channel carries only the plurality of HARQ acknowledgements, and

wherein the uplink control channel includes an indicator indicating that the uplink control channel carries only the plurality of HARQ acknowledgements.