Patent ID: 8867430

Claim:
A method of performing a hybrid automatic repeat request (HARQ) process by a source station in a wireless communication system, the method comprising: receiving a message from a destination station, the message comprising HARQ information and the HARQ information indicating supportable HARQ timings of the destination station; transmitting data to the destination station at a first downlink subframe of a first downlink carrier and a first downlink subframe of a second downlink carrier; receiving acknowledgment (ACK) or negative-acknowledgement (NACK) signals for the data from the destination station at one uplink subframe of an uplink carrier; and retransmitting the data at a second downlink subframe of the first downlink carrier and a third downlink subframe of the second downlink carrier, when the NACK signal is received, wherein a time interval from the first downlink subframe of the first downlink carrier to the second downlink subframe of the first downlink carrier is fixed to 8 subframes, wherein a time interval from the first downlink subframe of the second downlink carrier to the third downlink subframe of the second downlink carrier is selected among the supportable HARQ timings indicated by the message, and wherein a time interval from the first downlink subframe of the first downlink carrier to the one uplink subframe is fixed to 4 subframes.