Apparatus and method of channel access priority determination for sidelink transmission

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:

provide a mapping relationship between PC5 Quality of service (QoS) Indicators (PQIs) and Channel Access Priority Classes (CAPCs), based on one or more delay requirements of the PQIs; and

in response to presence of only a Sidelink Data Radio Bearer (SL-DRB) in a Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for SL transmission to an other UE:

determine, from the mapping relationship, a corresponding CAPC for the SL-DRB from one or more PQIs from the SL-DRB; and

determine a CAPC for the SL-MAC PDU for the SL transmission to the other UE based on the corresponding CAPC of the SL-DRB;

in response to presence of a Sidelink Signaling Radio Bearer (SL-SRB) in the Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for the SL transmission to the other UE:

determine a corresponding CPAC of the SL-SRB; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the other UE based on at least the corresponding CAPC of the SL-SRB as determined; and

in response to presence of only a SL Media Access Control (MAC) Control Element (CE) for the SL transmission to the other UE:

determine a corresponding CPAC of the MAC CE; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the other UE based on at least the corresponding CAPC of the MAC CE.

2 . 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:

provide a mapping relationship between PC5 Quality of service (QoS) Indicators (PQIs) and Channel Access Priority Classes (CAPCs), based on one or more delay requirements of the PQIs; and

in response to presence of only Sidelink Traffic Channel (STCH) Service Data Units (SDUs) from one or multiple Sidelink Data Radio Bearers (SL-DRBs) in a Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for SL transmission to an other UE:

determine, from the mapping relationship, a corresponding CAPC for the one or multiple SL-DRBs from one or more PQIs from the one or multiple SL-DRBs; and

determine a CAPC for the SL-MAC PDU for the SL transmission to the other UE based on the corresponding CAPC of the one or more multiple SL-DRBs;

in response to presence of Sidelink Control Channel (SCCH) Service Data Unit (SDUs) from one or multiple Sidelink Signaling Radio Bearer (SL-SRB) in the Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for the SL transmission to the other UE:

determine a corresponding CPAC of the SL-SRB; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the other UE based on at least the corresponding CAPC of the SL-SRB as determined; and

in response to presence of only a SL Media Access Control (MAC) Control Element (CE) for the SL transmission to the other UE:

determine a corresponding CPAC of the MAC CE; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the other UE based on at least the corresponding CAPC of the MAC CE.

3 . The UE of claim 2 , wherein the SL transmission of the SL-MAC PDU takes place on an unlicensed band.

4 . The UE of claim 2 , wherein the mapping relationship between the PQIs and the CAPCs maps a PQI with more stringent delay requirement to a CAPC of higher priority.

5 . The UE of claim 3 , wherein the CAPCs comprise an additional CAPC that has a priority higher than all permissible CAPCs of 5G QoS Indicator (5QI) for Uu interface, and the mapping relationship between the PQIs and the CAPCs maps a delay critical PQI to the additional CAPC.

6 . The UE of claim 2 , wherein the corresponding CAPC for the SL-SRB is to be associated with a highest priority of the CAPCs.

7 . The UE of claim 2 , wherein the corresponding CAPC for the MAC CE is to be associated with a highest priority of the CAPCs.

8 . The UE of claim 2 , wherein the at least one processor is configured to cause the UE to associate a corresponding CAPC for Physical Sidelink Feedback Channel (PSFCH) with a highest priority of the CAPCs.

9 . The UE of claim 2 , wherein the at least one processor is configured to cause the UE to associate, in response to presence of a Sidelink Control Channel (SCCH) or the SL-SRB in the SL MAC Protocol Data Unit (PDU), a CAPC of a highest priority is used for transmission of the SL-MAC PDU.

10 . The UE of claim 2 , wherein the at least one processor is configured to cause the UE to associate, upon determining that a Sidelink Media Access Control (SL MAC) Control Element (CE) is included in the SL MAC PDU, the CAPC for the SL-MAC PDU with a highest priority for the SL transmission.

11 . The UE of claim 2 , wherein the at least one processor is configured to cause the UE to associate, in response to presence of only data in the SL-MAC PDU, the CAPC for the SL-MAC PDU with a lowest priority of the CAPCs SL transmission.

12 . The UE of claim 2 , wherein the at least one processor is configured to cause the UE to:

receive a signaling for indication of a CAPC used by a base station; and

determine whether to transmit the SL-MAC PDU by comparing the indicated CAPC against the determined CAPC for the SL-MAC PDU for the SL transmission.

13 . The UE of claim 12 , wherein the at least one processor is configured to cause the UE to transmit, upon determining that the determined CAPC for the SL-MAC PDU has a higher priority than the indicated CAPC, the SL MAC PDU.

14 . The UE of claim 12 , wherein the at least one processor is configured to cause the UE to transmit the SL MAC PDU within a base station Channel Occupancy Time (COT).

15 . The UE of claim 12 , wherein the at least one processor is configured to cause the UE to upon determining that the determined CAPC for the SL-MAC PDU has a lower priority than the indicated CAPC, not transmit the SL-MAC PDU.

16 . A processor for wireless communication, comprising:

at least one controller coupled with at least one memory and configured to cause the processor to:

provide a mapping relationship between PC5 Quality of service (QoS) Indicators (PQIs) and Channel Access Priority Classes (CAPCs), based on one or more delay requirements of the PQIs; and

in response to presence of only Sidelink Traffic Channel (STCH) Service Data Units (SDUs) from one or multiple Sidelink Data Radio Bearers (SL-DRBs) in a Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for SL transmission to a UE:

determine, from the mapping relationship, a corresponding CAPC for the one or multiple SL-DRBs from one or more PQIs from the one or multiple SL-DRBs; and

determine a CAPC for the SL-MAC PDU for the SL transmission to the UE based on the corresponding CAPC of the one or more multiple SL-DRBs;

in response to presence of Sidelink Control Channel (SCCH) Service Data Unit (SDUs) from one or multiple Sidelink Signaling Radio Bearer (SL-SRB) in the Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for the SL transmission to the UE:

determine a corresponding CPAC of the SL-SRB; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the UE based on at least the corresponding CAPC of the SL-SRB as determined; and

in response to presence of only a SL Media Access Control (MAC) Control Element (CE) for the SL transmission to the UE:

determine a corresponding CPAC of the MAC CE; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the UE based on at least the corresponding CAPC of the MAC CE.

17 . The processor of claim 16 , wherein the SL transmission of the SL-MAC PDU takes place on an unlicensed band.

18 . The processor of claim 16 , wherein the mapping relationship between the PQIs and the CAPCs maps a PQI with more stringent delay requirement to a CAPC of higher priority.

19 . The processor of claim 17 , wherein the CAPCs comprise an additional CAPC that has a priority higher than all permissible CAPCs of 5G QoS Indicator (5QI) for Uu interface, and the mapping relationship between the PQIs and the CAPCs maps a delay critical PQI to the additional CAPC.

20 . A processor for wireless communication, comprising:

at least one controller coupled with at least one memory and configured to cause the processor to:

provide a mapping relationship between PC5 Quality of service (QoS) Indicators (PQIs) and Channel Access Priority Classes (CAPCs) based on one or more delay requirements of the PQIs; and

in response to presence of only a Sidelink Data Radio Bearer (SL-DRB) in a Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for SL transmission to a UE:

determine, from the mapping relationship, a corresponding CAPC for the SL-DRB from one or more PQIs from the SL-DRB; and

determine a CAPC for the SL-MAC PDU for the SL transmission to the UE based on the corresponding CAPC of the SL-DRB;

in response to presence of a Sidelink Signaling Radio Bearer (SL-SRB) in the Sidelink Media Access Control (SL-MAC) Protocol Data Unit (PDU) for the SL transmission to the UE:

determine a corresponding CPAC of the SL-SRB; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the UE based on at least the corresponding CAPC of the SL-SRB as determined; and

in response to presence of only a SL Media Access Control (MAC) Control Element (CE) for the SL transmission to the UE:

determine a corresponding CPAC of the MAC CE; and

determine the CAPC for the SL-MAC PDU for the SL transmission to the UE based on at least the corresponding CAPC of the MAC CE.