QUALCOMM Incorporated
RANDOM ACCESS PROCEDURE FALLBACK

Abstract:

This disclosure provides systems, methods and apparatus for wireless communications that support fallback from a 2-step to a 4-step random access procedures. A user equipment (UE) may establish a connection with a base station using a random access procedure. The random access procedure may be a 2-step random access procedure and reduce a number of handover exchange messages. The 2-step random access procedure may include the UE transmitting, to the base station, a first random access message including a preamble and a payload. In some implementations, the base station may receive the preamble but fail to receive or decode the payload. The random access procedure may utilize the received preamble information instead of performing retransmission of the first random access message. The base station may transmit a second random access message to the UE indicating, explicitly or implicitly, a fallback to a 4-step random access procedure for connection establishment.