This disclosure provides systems, methods, and apparatuses for random access channel (RACH) occasions that overlap each other in time and frequency. In one aspect, the RACH occasions may use different preamble sequence sets. A base station may signal configuration information indicating the preamble sequence sets for the RACH occasions and information indicating a time-frequency resource allocation of the RACH occasions. A UE may perform a random access procedure in accordance with the configuration information.