Method and apparatus for random access in NTN

A method of operating a user equipment (UE), the method comprising:

• identifying configuration information including a first set of resources and a second set of resources for a random access channel (RACH) operation;
• determining whether current location information of the UE is valid for the RACH operation;
• selecting the first set of resources based on a determination that the current location information of the UE is valid;
• selecting the second set of resources based on a determination that the current location information of the UE is invalid;
• transmitting a RACH preamble on the selected first or second set of resources;
• and
• receiving, in response to transmitting the RACH preamble, a random access response (RAR) medium access control protocol data unit (MAC PDU) (RAR MAC PDU),
• wherein the RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources.

A base station (BS) in a wireless communication system, the BS comprising:

• a processor configured to generate configuration information including a first set of resources and a second set of resources for a random access channel (RACH) operation;
• and
• a transceiver configured to:
• transmit the configuration information including the first set of resources and the second set of resources for the RACH operation,
• receive a RACH preamble on the first or second set of resources;
• and
• transmit, in response to receiving the RACH preamble, a random access response (RAR) medium access control protocol data unit (MAC PDU) (RAR MAC PDU),
• wherein the RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources, and
• wherein the first set of resources is for when current location information of a user equipment (UE) is valid and the second set of resources is for when the current location information of the UE is invalid.