Hybrid automatic repeat request (harq) handling for discontinuous reception

Abstract

This disclosure provides systems, methods, and apparatuses, including computer programs encoded on computer storage media, for wireless communications and more specifically for handling hybrid automatic repeat request (HARQ) processes with discontinuous reception (DRX) operations. In some implementations, a user equipment (UE) may use a timer to maintain an ON duration in a DRX cycle based on receiving a downlink control information (DCI) message with a data-to-feedback timing indicator (for example, a K1 value) indicating a non-numeric value for a data message. For example, the UE may receive a DCI message with feedback timing for the data message based on maintaining the ON duration. In some other implementations, a UE may use a timer to maintain an ON duration following a feedback opportunity to support dynamic group-based HARQ messaging. For example, the UE may receive a DCI message requesting a retransmission of feedback information based on maintaining the ON duration.

1 - 37 . (canceled) 
     
     
         38 . An apparatus for wireless communications, comprising:
 a processing system configured to:
 receive a downlink control information (DCI) message comprising a data-to-feedback timing indicator, wherein the DCI message schedules a downlink data message and the data-to-feedback timing indicator is a value not indicating feedback timing; 
 postpone a feedback transmission for the downlink data message based on the value; 
 activate a timer based on the value; 
 enter an active mode when the timer is active to monitor information for a downlink control channel; and 
 enter an inactive mode when the timer expires to stop monitoring for a downlink control channel. 
   
     
     
         39 . The apparatus of  claim 38 , wherein the value is a negative number. 
     
     
         40 . The apparatus of  claim 38 , wherein:
 the timer comprises a retransmission timer for downlink retransmissions and is associated with a hybrid automatic repeat request (HARD) process corresponding to the downlink data message.   
     
     
         41 . The apparatus of  claim 40 , wherein:
 the timer comprises a drx-RetransmissionTimerDL.   
     
     
         42 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 output a feedback message for the downlink data message according to feedback timing indicated by a second DCI message; and   activate a round-trip time timer in a first symbol after outputting the feedback message.   
     
     
         43 . The apparatus of  claim 42 , wherein the processing system is further configured to:
 activate a retransmission timer in a first symbol after expiration of the round-trip time timer based on the feedback message comprising a negative acknowledgment (NACK) for the downlink data message; and   monitor for the downlink control channel while the retransmission timer is active.   
     
     
         44 . The apparatus of  claim 43 , wherein:
 the round-trip time timer comprises a drx-HARQ-RTT-TimerDL; and   the retransmission timer comprises a drx-RetransmissionTimerDL.   
     
     
         45 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 deactivate the timer based on receiving a second DCI message indicating feedback timing for the downlink data message.   
     
     
         46 . The apparatus of  claim 45 , wherein:
 deactivating the timer comprises deactivating the timer in a first symbol after receiving the second DCI message or in a first symbol after a feedback transmission corresponding to the feedback timing indicated by the second DCI message.   
     
     
         47 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 receive the downlink data message based on the DCI message;   store feedback information for the downlink data message based on the DCI message indicating the value; and   output a feedback message comprising the feedback information for the downlink data message according to feedback timing indicated by a second DCI message.   
     
     
         48 . The apparatus of  claim 47 , wherein:
 the feedback message comprises a hybrid automatic repeat request (HARD) acknowledgment message.   
     
     
         49 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 receive a radio resource control (RRC) message indicating an active duration of the timer.   
     
     
         50 . The apparatus of  claim 49 , wherein:
 the active duration comprises a first active duration of the timer specific to receiving DCI messages indicating the value; and   the RRC message further indicates a second active duration of the timer.   
     
     
         51 . The apparatus of  claim 38 , wherein:
 the timer is specific to a hybrid automatic repeat request (HARD) process for the downlink data message.   
     
     
         52 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 deactivate the timer based on the timer running for an active duration of the timer;   enter a low power mode based on deactivating the timer; and   refrain from monitoring for the downlink control channel while in the low power mode.   
     
     
         53 . The apparatus of  claim 52 , wherein the processing system is further configured to:
 enter the low power mode based on a user equipment (UE) being outside of an ON duration of a discontinuous reception (DRX) mode and each timer corresponding to monitoring for the downlink control channel being deactivated.   
     
     
         54 . The apparatus of  claim 38 , wherein the processing system is further configured to:
 operate according to a discontinuous reception (DRX) mode; and   monitor for the downlink control channel during an ON duration of the DRX mode, wherein the DCI message is received based on monitoring for the downlink control channel during the ON duration of the DRX mode.   
     
     
         55 . The apparatus of  claim 38 , included in a user equipment (UE). 
     
     
         56 . An apparatus for wireless communications, comprising:
 a processing system configured to:
 output a downlink control information (DCI) message comprising a data-to-feedback timing indicator, wherein the DCI message schedules a downlink data message and the data-to-feedback timing indicator is a value not indicating feedback timing; and 
 determine an active time for a user equipment (UE) to monitor for a downlink control channel based on a timer, wherein the timer is activated based on the value. 
   
     
     
         57 . The apparatus of  claim 56 , wherein the value is a negative number. 
     
     
         58 . The apparatus of  claim 56 , wherein:
 the timer comprises a retransmission timer for downlink retransmissions and is associated with a hybrid automatic repeat request (HARD) process corresponding to the downlink data message.   
     
     
         59 . The apparatus of  claim 56 , wherein the processing system is further configured to:
 output a radio resource control (RRC) message indicating an active duration of the timer.   
     
     
         60 . The apparatus of  claim 59 , wherein:
 the active duration comprises a first active duration of the timer specific to receiving DCI messages indicating the value; and   the RRC message further indicates a second active duration of the timer.   
     
     
         61 . The apparatus of  claim 56 , wherein the processing system is further configured to:
 output the downlink data message based on the DCI message.   
     
     
         62 . A method for wireless communications, comprising:
 receiving a downlink control information (DCI) message comprising a data-to-feedback timing indicator, wherein the DCI message schedules a downlink data message and the data-to-feedback timing indicator is a value not indicating feedback timing;   postponing a feedback transmission for the downlink data message based on the value;   activating a timer based on the value;   entering an active mode when the timer is active to monitor information for a downlink control channel; and   entering an inactive mode when the timer expires to stop monitoring for a downlink control channel.   
     
     
         63 . The method of  claim 62 , wherein the value is a negative number. 
     
     
         64 . The method of  claim 62 , wherein:
 the timer comprises a retransmission timer for downlink retransmissions and is associated with a hybrid automatic repeat request (HARQ) process corresponding to the downlink data message.   
     
     
         65 . A method for wireless communications, comprising:
 transmitting a downlink control information (DCI) message comprising a data-to-feedback timing indicator, wherein the DCI message schedules a downlink data message and the data-to-feedback timing indicator is a value not indicating feedback timing; and   determining an active time for a user equipment (UE) to monitor for a downlink control channel based on a timer, wherein the timer is activated based on the value.   
     
     
         66 . The method of  claim 65 , wherein the value is a negative number. 
     
     
         67 . The method of  claim 65 , wherein:
 the timer comprises a retransmission timer for downlink retransmissions and is associated with a hybrid automatic repeat request (HARQ) process corresponding to the downlink data message.