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US-12621084-B2 - SL HARQ buffer management for NR vehicular communication

US12621084B2US 12621084 B2US12621084 B2US 12621084B2US-12621084-B2

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.

Inventors

  • Joachim Loehr
  • Prateek Basu Mallick
  • Karthikeyan Ganesan
  • Ravi Kuchibhotla

Assignees

  • LENOVO (SINGAPORE) PTE. LTD.

Dates

Publication Date
20260505
Application Date
20230725

Claims (20)

  1. 1 . A user equipment (UE) for wireless communication, comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the UE to: store a transport block (TB) in a transmission buffer associated with a sidelink (SL) hybrid automatic repeat request (HARQ) process associated with a scheduled SL transmission; determine whether a positive acknowledgement (ACK) for the TB is received; determine whether a maximum transmission time associated with the TB is reached; transmit the ACK to a base station in response to the ACK being received and in response to the maximum transmission time being reached; flush the transmission buffer associated with the SL HARQ process in response to transmitting the ACK or in response to the maximum transmission time being reached; and enable the SL HARQ process for new data in response to transmitting the ACK.
  2. 2 . The UE of claim 1 , wherein the at least one processor is further configured to cause the UE to overwrite the transmission buffer with other data.
  3. 3 . The UE of claim 2 , wherein the other data comprises data having a higher priority than the TB.
  4. 4 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to: transmit the TB to a receiver UE (Rx UE); and receive the ACK from the Rx UE.
  5. 5 . The UE of claim 4 , wherein the at least one processor is further configured to cause the UE to flush the transmission buffer in response to a downlink control information (DCI).
  6. 6 . The UE of claim 1 , wherein the at least one processor is further configured to cause the UE to: initiate a timer in response to storing the TB in the transmission buffer; and flush the transmission buffer in response to an expiration of the timer.
  7. 7 . The UE of claim 6 , wherein a length of the timer is based on the maximum transmission time, and wherein the maximum transmission time is a packet delay budget associated with the TB.
  8. 8 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to store new data in the transmission buffer.
  9. 9 . A processor for wireless communication, comprising: at least one controller coupled with at least one memory and configured to cause the processor to: store a transport block (TB) in a transmission buffer associated with a sidelink (SL) hybrid automatic repeat request (HARQ) process associated with a scheduled SL transmission; determine whether a positive acknowledgement (ACK) for the TB is received; determine whether a maximum transmission time associated with the TB is reached; transmit the ACK to a base station in response to the ACK being received and in response to the maximum transmission time being reached; flush the transmission buffer associated with the SL HARQ process in response to transmitting the ACK or in response to the maximum transmission time being reached; and enable the SL HARQ process for new data in response to transmitting the ACK.
  10. 10 . The processor of claim 9 , wherein the at least one controller is further configured to cause the processor to overwrite the transmission buffer with other data.
  11. 11 . The processor of claim 10 , wherein the other data comprises data having a higher priority than the TB.
  12. 12 . The processor of claim 9 , wherein the at least one controller is configured to cause the processor to: transmit the TB to a receiver user equipment (Rx UE); and receive the ACK from the Rx UE.
  13. 13 . The processor of claim 12 , wherein the at least one controller is further configured to cause the processor to flush the transmission buffer in response to a reception of a downlink control information (DCI).
  14. 14 . The processor of claim 9 , wherein the at least one controller is further configured to cause the processor to: initiate a timer in response to storing the TB in the transmission buffer, and flush the transmission buffer in response to expiry of the timer.
  15. 15 . The processor of claim 14 , wherein a length of the timer is based on the maximum transmission time, and wherein the maximum transmission time is a packet delay budget associated with the TB.
  16. 16 . The processor of claim 9 , wherein to enable the SL HARQ process for new data, the at least one controller is configured to cause the processor to store new data in the transmission buffer.
  17. 17 . A method of a user equipment (UE), the method comprising: storing a transport block (TB) in a transmission buffer associated with a sidelink (SL) hybrid automatic repeat request (HARQ) process associated with a scheduled SL transmission; determining whether a positive acknowledgement (ACK) for the TB is received; determining whether a maximum transmission time associated with the TB is reached; transmitting the ACK to a base station in response to the ACK being received and in response to the maximum transmission time being reached; flushing the transmission buffer associated with the SL HARQ process in response to transmitting the ACK or in response to the maximum transmission time being reached; and enabling the SL HARQ process for new data in response to transmitting the ACK.
  18. 18 . The method of claim 17 , further comprising overwriting the transmission buffer with other data.
  19. 19 . The method of claim 18 , wherein the other data comprises data having a higher priority than the TB.
  20. 20 . The method of claim 17 , further comprising: transmitting the TB to a receiver UE (Rx UE); and receiving the ACK from the Rx UE.

Description

FIELD The subject matter disclosed herein relates generally to wireless communications and more particularly relates to sidelink HARQ operation and buffer management for NR vehicular communication. BACKGROUND The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project (“3GPP”), Fifth Generation Core (“5GC”), Fifth Generation System (“5GS”), Authentication, Authorization and Accounting (“AAA”), Access and Mobility Management Function (“AMF”), Positive-Acknowledgment (“ACK”), Application Programming Interface (“API”), Base Station (“BS”), Control Element (“CE”), Core Network (“CN”), Control Plane (“CP”), Dedicated Short Range Communication (“DSRC”), Downlink Control Information (“DCI”), Downlink (“DL”), Discontinuous Transmission (“DTX”), Enhanced Mobile Broadband (“eMBB”), Evolved Node-B (“eNB”), Evolved Packet Core (“EPC”), General Packet Radio Service (“GPRS”), Global System for Mobile Communications (“GSM”), Hybrid Automatic Repeat Request (“HARQ”), Home Subscriber Server (“HSS”), Log Likelihood Ratio (“LLR”), Long Term Evolution (“LTE”), Multiple Access (“MA”), Mobility Management (“MM”), Mobility Management Entity (“MME”), Negative-Acknowledgment (“NACK”) or (“NAK”), New Generation (5G) Node-B (“gNB”), New Radio (“NR”, a 5G radio access technology; also referred to as “5G NR”), Network Slice Selection Assistance Information (“NSSAI”), Packet Data Unit (“PDU”, used in connection with ‘PDU Session’), Physical Broadcast Channel (“PBCH”), Physical Downlink Control Channel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), Physical Random Access Channel (“PRACH”), Physical Uplink Control Channel (“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Public Land Mobile Network (“PLMN”), Quality of Service (“QoS”), Radio Access Network (“RAN”), Radio Access Technology (“RAT”), Random-Access Channel (“RACH”), Receive (“Rx”), Scheduling Request (“SR”), Shared Channel (“SCH”), Session Management (“SM”), Session Management Function (“SMF”), Single Network Slice Selection Assistance Information (“S-NSSAI”), System Information Block (“SIB”), Transport Block (“TB”), Transmit (“Tx”), Unified Data Management (“UDM”), User Data Repository (“UDR”), Uplink Control Information (“UCI”), User Entity/Equipment (Mobile Terminal) (“UE”), Uplink (“UL”), User Plane (“UP”), Universal Mobile Telecommunications System (“UMTS”), Ultra-reliability and Low-latency Communications (“URLLC”), and Worldwide Interoperability for Microwave Access (“WiMAX”). As used herein, “HARQ-ACK” may represent collectively the Positive Acknowledge (“ACK”) and the Negative Acknowledge (“NACK”) and Discontinuous Transmission (“DTX”). ACK means that a TB is correctly received while NACK (or NAK) means a TB is erroneously received. DTX means that no TB was detected. In certain wireless communication systems, V2X communication allows vehicles to communicate with moving parts of the traffic system around them. Two resource allocation modes are used in LTE V2x communication which are also considered as a baseline for corresponding resource allocation modes in NR v2x communication. Mode-1 corresponds to a NR network-scheduled V2X communication mode. Mode-2 corresponds to an LTE network-scheduled V2X communication mode. Mode-3 corresponds to a NR UE-scheduled V2X communication mode. Mode-4 corresponds to an LTE UE-scheduled V2X communication mode. In LTE V2X HARQ operation is limited to blind retransmission without any HARQ feedback. NR V2X communication may support HARQ feedback signaling for SL transmission. However, UE behavior for SL HARQ protocol operation for NR V2X communication is not specified. BRIEF SUMMARY Methods for scheduling a sidelink transmission are disclosed. Apparatuses and systems also perform the functions of the methods. One method of a remote unit, e.g., a UE, for scheduling a sidelink transmission includes configuring a set of SL LCHs with at least one Uu LCH restriction parameter, wherein the SL LCHs communicate data over a PC5 interface. The method includes receiving, via internal process, a SL buffer status reporting trigger for a first SL LCH and determining that an UL-SCH resource for a new transmission is available. The method includes 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. One method of a remote unit, e.g., a Tx UE, for scheduling a sidelink transmission includes transmitting a first TB on SL resources using a first SL mode, where the TB is associated with a first SL HARQ process. The method includes 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. One method of a remote u