Method for performing an ack/nack indication based on the uplink grants over multiple subframes in a wireless communication system and a device therefor

A method for a User Equipment (UE) operating in a wireless communication system, the method comprising:

• starting a timer when UL grant is received from an eNB, wherein the UL grant is valid while the timer is running;
• transmitting data using the UL grant if the data is generated while the timer is running;
• starting monitoring an Acknowledgement (ACK) indication for the transmitted data when the timer expires;
• triggering a buffer status reporting (BSR) if the UE considers that the transmission of the data is not successful according to result of the monitoring.

A User Equipment (UE) for operating in a wireless communication system, the UE comprising:

• a Radio Frequency (RF) module;
• and
• a processor operably coupled with the RF module and configured to:
• start a timer when an uplink grant is received from an eNB, wherein the uplink grant is valid while the timer is running;
• transmit data using the uplink grant if the data is generated while the timer is running;
• monitor an Acknowledgement (ACK) indication or or a Negative-Acknowledgement (NACK) indication for the transmitted data on a subframe;
• check whether the timer is running or not if the ACK indication for the transmitted data is not received on the subframe or the NACK indication for the transmitted data is received on the subframe;
• and
• retransmit the data using the uplink grant if the timer is running.

A User Equipment (UE) for operating in a wireless communication system, the UE comprising:

• a Radio Frequency (RF) module;
• and
• a processor operably coupled with the RF module and configured to:
• start a timer when uplink grant is received from an eNB, wherein the uplink grant is valid while the timer is running;
• transmit data using the uplink grant if the data is generated while the timer is running;
• start monitoring an Acknowledgement (ACK) indication for the transmitted data when the timer expires;
• and
• trigger a buffer status reporting (BSR) if the UE considers that the transmission of the data is not successful according to result of the monitoring.