US Patent 11490346 Open loop timing control for 2-step RACH

In some aspects, a user equipment (UE) determines a transmission gap adjustment (TGA) for a first message (msgA) of a 2 step random access channel (RACH) procedure based on measurement of a reference signal transmitted by a base station as well as the radio resource configuration (RRC) configurations for msgA. In other aspects, a base station transmits a system information block (SIB) or RRC signaling that indicates at least one possible configuration of the TGA, and UEs determine the TGA depending on RRC state. Connected mode UEs having a timing alignment (TA) timer running may determine the TGA based on a previous TA. UEs in other RRC modes determine the TGA based on the possible configuration transmitted in the SIB or RRC signaling. Advantageously, 2 step RACH UEs are able to communicate with the base station without the closed loop TA information provided by a 4 step RACH.