US Patent 11395345 PRACH configuration on NR-U

Physical random access channel (PRACH) configuration on new radio unlicensed (NR-U) networks is disclosed. A UE may perform PRACH transmission either with a transmission opportunity (TXOP) or outside of a TXOP. The UE monitors for a control signal from a base station, such as a preamble or common control signal, identifying a TXOP. The UE may obtain an autonomous random access configuration for communications outside of the current TXOP that identifies a random access slot includes a plurality of random access occasions. If the UE fails to detect the control signal, it transmits an autonomous random access signal in a random access occasion corresponding to a beam direction of its location in relation to the base station. Otherwise, upon detection of the control signal and receipt of a trigger signal, the UE may transmit a random access request within the TXOP.