QUALCOMM Incorporated
SOUNDING REFERENCE SIGNALS TRIGGERED BY RANDOM ACCESS MESSAGE 2 FOR RANDOM ACCESS MESSAGE 4 QUASI CO-LOCATION

Abstract:

Apparatus, methods, and computer-readable media for sounding reference signals (SRSs) triggered by random access channel (RACH) message 2 for RACH message 4 physical downlink shared channel quasi co-location (QCL) are disclosed herein. A user equipment (UE) may transmit, to a base station via a transmit beam over a random access channel, a random access preamble and receive a random access response based on the random access preamble. The UE may transmit, to the base station via a plurality of transmit sub-beams, a plurality of SRS transmissions triggered by the random access response. The UE can receive, from the base station, a downlink control signal that includes an SRS resource indicator (SRI) that indicates a selected transmit sub-beam for a corresponding SRS transmission. The UE can use the SRI as QCL information for improved reception of downlink signaling with a refined receive sub-beam corresponding to the selected transmit sub-beam.