Method and apparatus for improving retransmission scheduling of sidelink communication in a wireless communication system

Abstract

Methods and apparatuses for improving retransmission scheduling of sidelink communications are disclosed herein. In one method, a first device monitors a down control signal for scheduling sidelink resource. The first device performs a sidelink transmission for a second device based on a first sidelink grant allocated by a base station. The first device determines a retransmission need of the sidelink transmission based on a Hybrid Automatic Repeat Request (HARQ) feedback of the sidelink transmission from the second device. The first device transmits a retransmission indication for the retransmission need to the base station. The first device starts or restarts a timer upon the transmission of the retransmission indication, wherein the timer is used for controlling a period of monitoring a downlink control resource set.

What is claimed is: 
     
         1 . A method of a first device to monitor downlink control signaling for scheduling sidelink resources, comprising:
 performing a sidelink transmission for a second device;   determining a retransmission need of the sidelink transmission based on a feedback of the sidelink transmission received from the second device;   transmitting a retransmission indication for the retransmission need to a base station; and   starting or restarting a timer upon the transmission of the retransmission indication, wherein the timer is used for controlling a round-trip time (RTT).   
     
     
         2 . The method of  claim 1 , wherein the sidelink transmission for the second device is based on a first sidelink grant allocated by the base station. 
     
     
         3 . The method of  claim 1 , wherein the feedback is a Hybrid Automatic Repeat Request (HARQ) feedback. 
     
     
         4 . The method of  claim 3 , wherein the HARQ feedback is received from the second device through a sidelink interface. 
     
     
         5 . The method of  claim 3 , further comprising:
 transmitting the retransmission indication to the base station if the first device does not receive the HARQ feedback from the second device.   
     
     
         6 . The method of  claim 3 , further comprising:
 transmitting the retransmission indication to the base station if the HARQ feedback from the second device indicates a reception failure of the sidelink transmission.   
     
     
         7 . The method of  claim 1 , wherein the timer is a RTT timer for sidelink. 
     
     
         8 . The method of  claim 1 , wherein the downlink control signaling includes a Physical Downlink Control Channel (PDCCH) or a coreset. 
     
     
         9 . The method of  claim 1 , wherein the downlink control signaling includes a set of PDCCH occasions. 
     
     
         10 . The method of  claim 1 , wherein the timer is used for triggering start of a retransmission timer for sidelink, and for controlling a period of monitoring a downlink control resource set. 
     
     
         11 . A first device configured to monitor downlink control signaling for scheduling sidelink resources, comprising:
 a memory; and   a processor operatively coupled to the memory, wherein the processor is configured to execute program code to:
 perform a sidelink transmission for a second device; 
 determine a retransmission need of the sidelink transmission based on a feedback of the sidelink transmission received from the second device; 
 transmit a retransmission indication for the retransmission need to a base station; and 
 start or restart a timer upon the transmission of the retransmission indication, wherein the timer is used for controlling a round-trip time (RTT). 
   
     
     
         12 . The first device of  claim 11 , wherein the sidelink transmission for the second device is based on a first sidelink grant allocated by the base station. 
     
     
         13 . The first device of  claim 11 , wherein the feedback is a Hybrid Automatic Repeat Request (HARQ) feedback. 
     
     
         14 . The first device of  claim 13 , wherein the HARQ feedback is received from the second device through a sidelink interface. 
     
     
         15 . The first device of  claim 13 , wherein the processor is further configured to execute program code to:
 transmit the retransmission indication to the base station if the first device does not receive the HARQ feedback from the second device.   
     
     
         16 . The first device of  claim 13 , wherein the processor is further configured to execute program code to:
 transmit the retransmission indication to the base station if the HARQ feedback from the second device indicates a reception failure of the sidelink transmission.   
     
     
         17 . The first device of  claim 11 , wherein the timer is a RTT timer for sidelink. 
     
     
         18 . The first device of  claim 11 , wherein the downlink control signaling includes a Physical Downlink Control Channel (PDCCH) or a coreset. 
     
     
         19 . The first device of  claim 11 , wherein the downlink control signaling includes a set of PDCCH occasions. 
     
     
         20 . The first device of  claim 11 , wherein the timer is used for triggering start of a retransmission timer for sidelink, and for controlling a period of monitoring a downlink control resource set.