Sl harq buffer management for nr vehicular communication

Abstract

Apparatuses, methods, and systems are disclosed for scheduling a sidelink transmission. One apparatus includes a processor and a transceiver that receives a TB on SL resources, where the TB is associated with a SL HARQ process. The processor stores the TB in a HARQ soft buffer and makes available the HARQ soft buffer for new data in response to a predefined trigger.

1 . A method of a remote unit comprising:
 configuring a set of sidelink (“SL”) logical channels (“LCHs”) with at least one Uu LCH restriction parameter, wherein the SL LCHs communicate data over a PC5 interface;   receiving, via internal process, a sidelink buffer status reporting trigger for a first SL LCH;   determining that an uplink shared channel (“UL-SCH”) resource for a new transmission is available;   determining that the at least one Uu LCH restriction parameter of the first SL LCH does not match the uplink transmission parameters associated with the UL-SCH resources available for the new transmission; and   triggering a Scheduling Request to a base unit via a Uu interface for PC5 resources.   
     
     
         2 . The method of  claim 1 , wherein the at least one Uu LCH restriction parameter comprises one or more of: maximum physical uplink shared channel duration, allowed subcarrier spacing, and allowed serving cell. 
     
     
         3 . The method of  claim 1 , wherein triggering the Scheduling Request occurs in response to detecting that a first parameter maxPUSCH-Duration configured for the first SL LCH has a smaller value than the PUSCH transmission duration associated with the UL-SCH resource available for the new transmission. 
     
     
         4 . The method of  claim 1 , wherein triggering the Scheduling Request occurs in response to detecting that a set of allowed Subcarrier Spacing for the first SL LCH does not include the Subcarrier Spacing associated with the UL-SCH resource available for the new transmission. 
     
     
         5 . The method of  claim 1 , wherein triggering the Scheduling Request occurs in response to determining that the UL-SCH resource available for the new transmission are later in time than a next physical uplink control channel transmission occasion for the Scheduling Request triggered for the first SL LCH. 
     
     
         6 . The method of  claim 1 , further comprising receiving a time threshold, wherein triggering the Scheduling Request occurs in response to determining that UL-SCH resource available for the new transmission are more than the time threshold away in time from the time the sidelink buffer status reporting trigger for the first SL LCH is received. 
     
     
         7 . A method of a remote unit comprising:
 transmitting a first transmission block (“TB”) on sidelink (“SL”) resources using a first SL mode, where the TB is associated with a first SL hybrid automatic repeat request (“HARQ”) process;   detecting a HARQ protocol error associated with the TB; and   retransmitting the TB on SL resources using a second SL mode in response to the HARQ protocol error.   
     
     
         8 . The method of  claim 7 , further comprising initiating a timer upon one of:
 generation of the TB,   initial transmission of the TB, and   placement of the TB in a HARQ transmission buffer,   wherein retransmitting the TB on SL resources using a second SL mode occurs while the timer is not expired.   
     
     
         9 . The method of  claim 8 , wherein the timer value is based on a packet delay budget associated with the TB. 
     
     
         10 . The method of  claim 7 , further comprising:
 storing the TB in a HARQ transmission buffer; and   making available the HARQ transmission buffer for new data in response to a predefined trigger.   
     
     
         11 . The method of  claim 10 , wherein the predefined trigger comprises expiry of a timer, wherein the timer is initiated in response to storing the TB in the HARQ transmission buffer. 
     
     
         12 . The method of  claim 11 , wherein the timer value is based on a packet delay budget associated with the TB. 
     
     
         13 . The method of  claim 10 , wherein the predefined trigger comprises one of: receiving an indication in downlink control information and sending an ACK corresponding to the TB to a base unit. 
     
     
         14 . The method of  claim 10 , wherein making available the HARQ soft buffer for new data comprises one of:
 flushing the HARQ soft buffer, and   replacing data stored in the HARQ soft buffer with new data.   
     
     
         15 . A method of a remote unit comprising:
 receiving a transmission block (“TB”) on sidelink (“SL”) resources, where the TB is associated with a SL HARQ process;   storing the TB in a HARQ soft buffer; and   making available the HARQ soft buffer for new data in response to a predefined trigger.   
     
     
         16 . The method of  claim 15 , wherein making available the HARQ soft buffer for new data comprises one of:
 flushing the HARQ soft buffer, and   replacing data stored in the HARQ soft buffer with new data.   
     
     
         17 . The method of  claim 15 , wherein the predefined trigger comprises expiry of a timer, wherein the timer is initiated in response to storing the TB in the HARQ soft buffer. 
     
     
         18 . The method of  claim 17 , wherein the length of the timer is based on at least one of: a packet delay budget associated with the TB, and some information carried in the Sidelink Control information accompanying the TB. 
     
     
         19 . The method of  claim 15 , wherein the predefined trigger comprises one of: sending an ACK corresponding to the TB to a V2X UE and receiving a second TB having a higher priority than the TB stored in the HARQ soft buffer. 
     
     
         20 . A method of a remote unit comprising:
 receiving a transmission block (“TB”) on sidelink (“SL”) resources, where the TB is associated with predefined number of blind HARQ retransmissions;   decoding the TB;   determining whether the TB is correctly decoded;   sending a positive HARQ acknowledgement prior to a last of the blind HARQ retransmissions in response to correctly decoding the TB; and   sending a negative HARQ acknowledgement in response to incorrectly decoding an initial transmission of the TB and each of the blind HARQ retransmissions the TB,   wherein no negative HARQ acknowledgement is sent prior to receiving the last of the blind HARQ retransmissions.