Multiple TRP PDSCH scheduling using DCI without TCI field
Aspects presented herein may enable a UE and/or a base station to identify a TCI state for each of the multiple TRPs when the DCI does not include a TCI state. For examples, aspects presented herein may enable the UE and/or the base station to identify TCI states from different TRPs based at least in part on one of a default beam rule, the TCI state used for transmitting PDCCH, or the TCI state used for transmitting previous/last PDSCH. In one aspect, an apparatus receives a single DCI from one TRP of a base station or multiple DCIs from multiple TRPs of the base station that do not contain a TCI state. Then the apparatus receive PDSCH from the multiple TRPs of the base station based on a TCI state in which the PDSCH is to be transmitted from each of the multiple TRPs of the base station.
1. An apparatus for wireless communication at a user equipment (UE), comprising:
memory; and
at least one processor coupled to the memory and configured to:
receive a single downlink control information (DCI) from one transmission and reception point (TRP) of a base station or multiple DCIs from multiple TRPs of the base station that do not contain a transmission configuration indicator (TCI) state; and
receive physical downlink shared channel (PDSCH) from the multiple TRPs of the base station based on a TCI state in which the PDSCH is to be transmitted from each of the multiple TRPs of the base station, wherein the TCI state for each of the multiple TRPs is based on TCI states for a previous PDSCH in a same bandwidth part (BWP) or in a same carrier component (CC).
2. The apparatus of claim 1 , wherein the TCI state is further based on a time difference between receiving the single DCI or the multiple DCIs and receiving the PDSCH.
3. The apparatus of claim 1 , wherein the single DCI is received from a single TRP of the base station scheduling the PDSCH from the multiple TRPs, and the TCI state for each of the multiple TRPs is further based on a default TCI codepoint if two or more TCI states are scheduled for the PDSCH.
4. The apparatus of claim 3 , wherein the default TCI codepoint comprises two different TCI states with lowest TCI state IDs from a set of TCI states.
5. The apparatus of claim 1 , wherein the multiple DCIs are received from the multiple TRPs of the base station, and the TCI state for each of the multiple TRPs is further based on a default TCI state associated with each of the multiple TRPs when two or more TCI states are scheduled for the PDSCH.
6. The apparatus of claim 5 , wherein each of the multiple TRPs is associated with a control resource set (CORESET) pool that comprises multiple TCI states, and the default TCI state for each of the multiple TRPs is selected from the CORESET pool corresponding to each of the multiple TRPs.
7. The apparatus of claim 6 , wherein the default TCI state corresponds to a CORESET with a lowest CORESET ID in the CORESET pool.
8. The apparatus of claim 1 , wherein the TCI state is further based on one or more TCI states used for receiving physical downlink control channel (PDCCH).
9. The apparatus of claim 8 , wherein the single DCI is received from a single TRP of the base station, and the TCI state for each of the multiple TRPs is based on a TCI codepoint that indicates a first TCI state used for the PDCCH comprising the DCI and a second TCI state that is not used by the base station for transmitting the PDCCH.
10. The apparatus of claim 9 , wherein the first TCI state is for the TRP from which the single DCI is received, and the second TCI state is for a second TRP.
11. The apparatus of claim 9 , wherein the TCI codepoint has a lowest codepoint ID among multiple TCI codepoints.
12. The apparatus of claim 8 , wherein the multiple DCIs are received from the multiple TRPs of the base station, and the TCI state for each of the multiple TRPs corresponds to the TCI state used for receiving the PDCCH comprising DCI from a respective TRP.
13. The apparatus of claim 1 , wherein the at least one processor and the memory are further configured to:
receive the PDSCH from a single TRP of the base station if there is no previous PDSCH in the same BWP or the same CC.
14. The apparatus of claim 1 , wherein the at least one processor and the memory are further configured to:
identify one or more of: a number of TCI states scheduled for the PDSCH based on a field in the DCI or a configuration, a mapping from antenna ports to the TCI state used to transmit the PDSCH based on a first field in the DCI or a first configuration, or a resource allocation for repetitions associated with the PDSCH based on a second field in the DCI or a second configuration.
15. The apparatus of claim 1 , wherein the single DCI or the multiple DCIs are received in a fallback DCI format.
16. The apparatus of claim 15 , wherein the fallback DCI format includes or identifies one or more of: a number of TCI states associated with the PDSCH, an antenna port field associated with the PDSCH, or a resource allocation for repetition associated with the PDSCH.
17. The apparatus of claim 1 , further comprising a transceiver coupled to the at least one processor.
18. A method of wireless communication at a user equipment (UE), comprising: receiving a single downlink control information (DCI) from one transmission and reception point (TRP) of a base station that do not contain a transmission configuration indicator (TCI) state; and receiving a physical downlink shared channel (PDSCH) from the multiple TRPs of the base station based on a TCI state in which the PDSCH is to be transmitted from each of the multiple TRPs of the base station, wherein the TCI state for each of the multiple TRPs is based on TCI states for a previous PDSCH in a same bandwidth part (BWP) or in a same carrier component (CC).
19. An apparatus for wireless communication at a base station, comprising:
memory; and
at least one processor coupled to the memory and configured to:
transmit, to a user equipment (UE), a single downlink control information (DCI) from one transmission and reception point (TRP) of the base station or multiple DCIs from multiple TRPs of the base station that do not contain a transmission configuration indicator (TCI) state; and
transmit physical downlink shared channel (PDSCH) to the UE through the multiple TRPs of the base station using a TCI state for each of the multiple TRPs, wherein the TCI state for each of the multiple TRPs is based on TCI states for a previous PDSCH in a same bandwidth part (BWP) or in a same carrier component (CC).
20. The apparatus of claim 19 , wherein the TCI state is further based on a time difference between transmitting the single DCI or the multiple DCIs and transmitting the PDSCH.
21. The apparatus of claim 19 , wherein the single DCI is transmitted from a single TRP of the base station scheduling the PDSCH from the multiple TRPs, the TCI state for each of the multiple TRPs is further based on a default TCI codepoint if two or more TCI states are scheduled for the PDSCH.
22. The apparatus of claim 21 , wherein the default TCI codepoint comprises two different TCI states with lowest TCI state IDs from a set of TCI states.
23. The apparatus of claim 19 , wherein the multiple DCIs are transmitted from the multiple TRPs of the base station, and the TCI state for each of the multiple TRPs is further based on a default TCI state associated with each of the multiple TRPs when two or more TCI states are scheduled for the PDSCH.
24. The apparatus of claim 23 , wherein each of the multiple TRPs is associated with a control resource set (CORESET) pool that comprises multiple TCI states, and the default TCI state for each of the multiple TRPs is selected from the CORESET pool corresponding to each of the multiple TRPs.
25. The apparatus of claim 24 , wherein the default TCI state corresponds to a CORESET with a lowest CORESET ID in the CORESET pool.
26. The apparatus of claim 19 , wherein the TCI state is further based on one or more TCI states used for transmitting physical downlink control channel (PDCCH).
27. The apparatus of claim 19 , wherein the at least one processor and the memory are further configured to:
transmit the PDSCH from a single TRP of the base station if there is no previous PDSCH in the same BWP or the same CC.
28. The apparatus of claim 19 , wherein the single DCI or the multiple DCIs are transmitted in a fallback DCI format.
29. A method of wireless communication at a base station, comprising: transmitting, to a user equipment (UE), a single downlink control information (DCI) from one transmission and reception point (TRP) of the base station or multiple DCIs from multiple TRPs of the base station that do not contain a transmission configuration indicator (TCI) state; and transmitting a physical downlink shared channel (PDSCH) to the UE through the multiple TRPs of the base station using a TCI state for each of the multiple TRPs, wherein the TCI state for each of the multiple TRPs is based on TCI states for a previous PDSCH in a same bandwidth part (BWP) or in a same carrier component (CC).