Determine a transport block size (TBS) included in transmissions over a sidelink channel
A method determines a number of physical sidelink shared channel (PSSCH) symbols and a number of PSSCH demodulation reference signal (DMRS) symbols that will occur in a timeslot that is used for scheduling. PSSCH DMRS locations in the timeslot are derived based on applying the PSSCH DMRS symbols and the PSSCH DMRS symbols to a look-up table. A number of PSSCH DMRS resource elements (REs) is calculated based on the PSSCH DMRS locations and a scheduled number of PSSCH sub-channels. This number of PSSCH DMRS REs is used to determine a transport block size (TBS) included in transmissions over a sidelink channel.
1. A method, performed by one or more processors of a user equipment (UE), comprising:
determining a reference number of physical sidelink shared channel (PSSCH) symbols and a reference number of PSSCH demodulation reference signal (DMRS) symbols that will occur in a timeslot that is used for scheduling;
deriving reference PSSCH DMRS locations in the timeslot, based on applying the reference number of PSSCH DMRS symbols and the reference number of PSSCH DMRS symbols to a look-up table; and
calculating a number of PSSCH DMRS resource elements (REs) based on the reference PSSCH DMRS locations and a scheduled number of PSSCH sub-channels, the number of PSSCH DMRS REs being used to determine a transport block size (TBS) of a TB included in transmissions over a sidelink channel to a second UE.
2. The method of claim 1 , wherein the reference number of PSSCH symbols is determined based on a total number of symbols included in the timeslot less a reference number of physical sidelink feedback channel (PSFCH) symbols.
3. The method of claim 2 , wherein the reference number of PSFCH symbols is determined based on selection among a plurality of pre-configured values, the selection being indicated by a value in sidelink control information (SCI).
4. The method of claim 1 , wherein determining the reference number of the PSSCH symbols and the reference number of the PSSCH DMRS symbols includes, in response to a physical sidelink feedback channel (PSFCH) periodicity being 2 or 4, selecting a reference number of the PSFCH symbols based on selection among a plurality of pre-configured values, the selection of the pre-configured values being indicated by a value in sidelink control information (SCI), and determining the reference number of the PSSCH symbols based on the PSFCH symbols.
5. The method of claim 1 , further comprising calculating a number of REs in a second stage sidelink control information (SCI) based on the reference PSSCH DMRS locations, a payload size of a second stage SCI format, a scheduled target coding rate, a number of PSSCH layers, and a beta offset for the second stage SCI.
6. The method of claim 5 , wherein the payload size of the second stage SCI format, the scheduled target coding rate, a number of PSSCH layers, and the beta offset for the second stage SCI are unchanged between an initial transmission and a retransmission of the second stage SCI.
7. A method performed by one or more processors of a user equipment (UE), comprising, comprising:
in response to a number of simultaneous physical sidelink feedback channel (PSFCH) transmissions exceeding a maximum transmission power of the UE,
determining a lower bound of the number of simultaneous PSFCH transmissions, based on the maximum transmission power of the UE and a reference power of a PSFCH transmission determined based on a nominal power of a PSFCH; and
including in a transmission, simultaneous PSFCH transmissions at least as many as the lower bound of the number of simultaneous PSFCH transmissions, but not exceeding the maximum transmission power of the UE.
8. The method of claim 7 , wherein the reference power is calculated as a sum of a) the nominal power of a PSFCH, b) 10 log 10(2 u ) where u is defined by subcarrier spacing, and c) αPSFCH*PL where αPSFCH is a path loss adaptation and PL is path loss.
9. The method of claim 8 , wherein the lower bound is determined as a larger of a) one, or b) a floor of: ten to the power of a difference between the maximum transmission power of the UE and the reference power divided by ten.
10. The method of claim 8 , wherein the lower bound is determined as a larger of a) one, or b) a ceiling of: ten to the power of a difference between the maximum transmission power of the UE and the reference power divided by ten.
11. A user equipment device comprising:
at least one antenna;
at least one radio, wherein the at least one radio is to perform cellular communications using a radio access technology that establishes a wireless link with a serving cell; and
one or more processors, configured to perform operations that include:
determining a reference number of physical sidelink shared channel (PSSCH) symbols and a reference number of PSSCH demodulation reference signal (DMRS) symbols that will occur in a timeslot in a transmission through a sidelink channel to a second UE;
deriving reference PSSCH DMRS locations in the timeslot, based on applying the reference number of PSSCH DMRS symbols and the reference number of PSSCH DMRS symbols to a look-up table; and
calculating a number of PSSCH DMRS resource elements (REs) based on the reference PSSCH DMRS locations and a scheduled number of PSSCH sub-channels, the number of PSSCH DMRS REs being used to determine a transport block size (TBS) of a TB included in transmissions over the sidelink channel to the second UE.
12. The user equipment device of claim 11 , wherein the reference number of PSSCH symbols is determined based on a total number of symbols included in the timeslot less a reference number of physical sidelink feedback channel (PSFCH) symbols.
13. The user equipment device of claim 12 , wherein the reference number of PSFCH symbols is determined based on selection among a plurality of pre-configured values, the selection being indicated by a value in sidelink control information (SCI).
14. The user equipment device of claim 11 , wherein determining the reference number of the PSSCH symbols and the reference number of the PSSCH DMRS symbols includes, in response to a physical sidelink feedback channel (PSFCH) periodicity being 2 or 4, selecting a reference number of the PSFCH symbols based on selection among a plurality of pre-configured values, the selection of the pre-configured values being indicated by a value in sidelink control information (SCI), and determining the reference number of the PSSCH symbols based on the PSFCH symbols.
15. The user equipment device of claim 11 , wherein the operations further include calculating a number of REs of a second stage sidelink control information (SCI) based on a payload size of a second stage SCI format, a scheduled target coding rate, a number of PSSCH layers, and a beta offset for the second stage SCI.
16. The user equipment device of claim 15 , wherein the payload size of the second stage SCI format, the scheduled target coding rate, the number of PSSCH layers, and the beta offset for the second stage SCI are unchanged between an initial transmission and a retransmission of the second stage SCI.
17. The user equipment device of claim 11 , wherein the operations further include:
in response to a number of simultaneous physical sidelink feedback channel (PSFCH) transmissions exceeding a maximum transmission power of the UE,
determining a lower bound of the number of simultaneous PSFCH transmissions, based on the maximum transmission power of the UE and a reference power of a PSFCH transmission determined based on a nominal power of a PSFCH; and
including in a transmission, simultaneous PSFCH transmissions at least as many as the lower bound of the number of simultaneous PSFCH transmissions, but not exceeding the maximum transmission power of the UE.
18. The user equipment device of claim 17 , wherein the reference power is calculated as a sum of a) the nominal power of a PSFCH, b) 10 log 10(2 u ) where u is defined by subcarrier spacing, and c) αPSFCH*PL where αPSFCH is a path loss adaptation and PL is path loss.
19. The user equipment device of claim 18 , wherein the lower bound is determined as a larger of a) one, or b) a floor of: ten to the power of a difference between the maximum transmission power of the UE and the reference power divided by ten.
20. The user equipment device of claim 18 , wherein the lower bound is determined as a larger of a) one, or b) a ceiling of: ten to the power of a difference between the maximum transmission power of the UE and the reference power divided by ten.