Method for performing retransmission in mimo wireless communication system and apparatus therefor

A method for performing retransmission at a user equipment of a MIMO wireless communication system, the method comprising:

• transmitting multiple transport blocks to a base station for a transmission unit time in accordance with uplink grant information, which includes a first new data indicator;
• receiving ACK/NACK (Acknowledgement/Negative-ACK) responses corresponding to the respective transport blocks and uplink grant information, which includes a second new data indicator, from the base station;
• and
• performing new transmission or retransmission for the multiple transport blocks in one transport block unit for a transmission unit time in accordance with the ACK/NACK responses and the second new data indicator, if transport rank is maintained.

A method for performing retransmission at a user equipment of a MIMO wireless communication system, the method comprising:

• transmitting a first transport block to a base station for a transmission unit time in accordance with uplink grant information, which includes a first new data indicator;
• receiving ACK/NACK (Acknowledgement/Negative-ACK) response corresponding to the first transport block and uplink grant information, which includes a second new data indicator, from the base station;
• and
• performing new transmission for a second transport block and new transmission or retransmission for the first transport block in accordance with the ACK/NACK response and the second new data indicator, if transport rank is increased,
• wherein the second new data indicator has a value different from that of the first new data indicator.

A user equipment comprising:

• a processor;
• and
• a radio frequency (RF) module supporting MIMO antennas and transmitting and receiving a radio signal to and from the outside under the control of the processor,
• wherein the processor transmits multiple transport blocks to a base station for a transmission unit time in accordance with uplink grant information, which includes a first new data indicator, receives ACK/NACK (Acknowledgement/Negative-ACK) responses corresponding to the respective transport blocks and uplink grant information, which includes a second new data indicator, from the base station, and
• performs new transmission or retransmission for the multiple transport blocks in one transport block unit for a transmission unit time in accordance with the ACK/NACK responses and the second new data indicator, if transport rank is reduced to 1.

A user equipment comprising:

• a processor;
• and
• a radio frequency (RF) module supporting MIMO antennas and transmitting and receiving a radio signal to and from the outside under the control of the processor,
• wherein the processor transmits multiple transport blocks to a base station for a transmission unit time in accordance with uplink grant information, which includes a first new data indicator, receives ACK/NACK (Acknowledgement/Negative-ACK) responses corresponding to the respective transport blocks and uplink grant information, which includes a second new data indicator, from the base station, and
• performs new transmission or retransmission for the multiple transport blocks in one transport block unit for a transmission unit time in accordance with the ACK/NACK responses and the second new data indicator, if transport rank is maintained.

A user equipment comprising:

• a processor;
• and
• a radio frequency (RF) module supporting MIMO antennas and transmitting and receiving a radio signal to and from the outside under the control of the processor,
• wherein the processor transmits a first transport block to a base station for a transmission unit time in accordance with uplink grant information, which includes a first new data indicator, receives ACK/NACK (Acknowledgement/Negative-ACK) response corresponding to the first transport block and uplink grant information, which includes a second new data indicator, from the base station, and performs new transmission for a second transport block and new transmission or retransmission for the first transport block in accordance with the ACK/NACK response and the second new data indicator, if transport rank is increased, and
• the second new data indicator has a value different from that of the first new data indicator.