Channel sensing for physical random access channel (PRACH) signals in new radio (NR) systems operating in the unlicensed spectrum

A method for a base station, comprising:

• receiving a first message from a user equipment (UE), the first message comprising a preamble of a random access channel (RACH) configured to perform a random access procedure;
• generating and transmitting a second message that indicates a reception of the preamble and comprising a time-adjustment command and a scheduling grant via a physical downlink channel for configuring a third message;
• receiving the third message from the UE based on a resource indicated by the scheduling grant of the second message;
• generating and transmitting a fourth message to transfer the UE to a connected state;
• and
• receiving a HARQ feedback from the UE based on the fourth message,
• wherein the third message includes a listen-before-talk (LBT) indication that indicates which LBT type the base station is to perform,
• wherein the third message comprises a UCI that includes two bits that comprise the LBT indication.

A method for a user equipment (UE), comprising:

• generating a first message comprising a preamble of a random access channel (RACH);
• receiving a second message indicating a reception of the preamble and comprising a scheduling grant via a physical downlink channel;
• generating a third message based on a resource indicated by the scheduling grant of the second message;
• receiving a fourth message comprising contention resolution information;
• and
• generating a hybrid automatic repeat request (HARQ) feedback based on the fourth message;
• wherein the third message includes a listen-before-talk (LBT) indication that indicates which LBT type a base station is to perform, and
• wherein at least two of:
• the first message, the second message, the third message, the fourth message, or the HARQ feedback share a channel occupancy time (COT) in a random access procedure, wherein the HARQ feedback is transmitted within 16 microseconds of the fourth message.