Systems, methods, and apparatuses for quasi-co-location (QCL) and spatial relation assumptions during random access procedures
Techniques described herein involve the use of quasi-co-location (QCL) capabilities and spatial relation assumption to enable a UE to designate a single beam for connections with a base station during a physical random access channel (PRACH) procedure. Once the PRACH procedure is complete, the beam may be reset after a pre-determined duration, which may account for decoding latency, or maintained until additional transmission configuration indication (TCI) is received. Also addressed are scenarios involving multiple transmission reception points (TRPs) and switching between beam management schemes based on one or more factors including device capabilities.
1. A baseband processor of a user equipment (UE), configured to perform operations comprising:
receiving, from a base station, transmission configuration indication (TCI) information that indicates a first beam as being associated with a channel;
causing transmission of a physical random access channel (PRACH) message to the base station on a second beam to initiate a PRACH procedure, wherein the second beam is different than the first beam;
during the PRACH procedure, communicating on the channel using the second beam;
detecting, after completion of the PRACH procedure, a trigger for resetting the beam associated with the channel, wherein the trigger comprises K symbols measured from a completion of the PRACH procedure, further wherein K is determined based on a subcarrier spacing of a downlink bandwidth part (DL BWP) or uplink bandwidth part (UL BWP); and
resetting the beam associated with the channel based on the trigger and the TCI information received from the base station.
2. The baseband processor of claim 1 , wherein the operations comprise detecting the trigger based on whether a first condition is met or a second condition is met, and wherein
in response to the first condition being met, the trigger comprises the K symbols; and
in response to the second condition being met, the trigger comprises receiving transmission configuration indication (TCI) information after completion of the PRACH procedure.
3. The baseband processor of claim 2 , wherein the first condition comprises the PRACH procedure being associated with a channel state information reference signal (CSI-RS).
4. The baseband processor of claim 2 , wherein the operations comprise determining whether the first condition or the second condition is met based on an indication in a PRACH procedure message received from the base station.
5. The baseband processor of claim 1 , wherein a beam associated with the PRACH procedure is applied during the PRACH procedure based on at least one of:
a capability of the UE; or
higher layer signaling from the base station.
6. The baseband processor of claim 2 , wherein the operations further comprise:
determining whether the first condition or the second condition is met based on
a radio access procedure type of the PRACH procedure.
7. The baseband processor of claim 6 , wherein:
the radio access procedure type comprises whether the PRACH procedure involves a scheduling request.
8. The baseband processor of claim 1 , wherein:
the PRACH procedure is associated with a channel state information reference signal (CSI-RS); and
the operations further comprise receiving, from the base station, information associating the TCI information with the CSI-RS.
9. The baseband processor of claim 1 , wherein the operations further comprise:
receiving, via higher layer signaling, information associating the base station with the channels, the information comprising a cell identifier and a TCI state of the channels.
10. The baseband processor of claim 1 , wherein the operations comprise communicating on all channels associated with the base station using the second beam during the PRACH procedure.
11. A baseband processor of a user equipment (UE), configured to perform operations comprising:
receiving, from a base station, transmission configuration indication (TCI) information that indicates that a first beam being associated with a channel;
causing transmission of a physical random access channel (PRACH) message to the base station on a second beam to initiate a PRACH procedure, wherein the second beam is different than the first beam;
during the PRACH procedure, communicating on the channel using the second beam:
receiving additional TCI information corresponding to an additional base station;
maintaining, during the PRACH procedure, an additional beam based on the additional TCI information for the additional base station;
detecting, after completion of the PRACH procedure, a trigger for resetting the beam associated with the channel; and
resetting the beam associated with the channel based on the trigger and the TCI information received from the base station.
12. The baseband processor of claim 11 , wherein the operations further comprise:
receiving, from the base station via higher layer signaling, the additional TCI information comprising a cell identifier and a TCI state.
13. The baseband processor of claim 11 , wherein the operations comprise communicating on all channels associated with the base station using the second beam during the PRACH procedure.
14. An apparatus of a base station, comprising one or more processors configured to perform operations comprising:
transmitting transmission configuration indication (TCI) information that indicates a first beam as being associated with a channel;
receive a physical random access channel (PRACH) message from a user equipment (UE) on a second beam, the PRACH message initiating a PRACH procedure between the base station and the UE, wherein the second beam is different than the first beam;
communicate on the channel with the UE during the PRACH procedure using the second beam the beam;
when a first condition is met communicate on the channel with the UE using the first beam after K symbols measured from completion of the PRACH procedure, wherein K is determined based on a subcarrier spacing of a DL BWP or UL BWP; and
when a second condition is met, communicate, after the PRACH procedure, new TCI information to cause the UE to reset a beam associated with the channel based on the new TCI information.
15. The apparatus of claim 14 , wherein the channels comprise a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), or a physical uplink shared channel (PUSCH).
16. The apparatus of claim 14 , wherein the first condition comprises the PRACH procedure being associated with a channel state information reference signal (CSI-RS).
17. The apparatus of claim 14 , wherein the operations comprise determining whether the first condition or the second condition is met based on an indication in a PRACH procedure message transmitted to the UE.
18. The apparatus of claim 14 , wherein the operations further comprise determining whether the first condition or the second condition is met based on a radio access procedure type of the PRACH procedure.