BACKGROUND

One of the aspects of 5G NR is the physical random access channel (PRACH) and the random access procedure (RACH procedure). In the RACH procedure, which is designed for uplink time synchronization, a wireless transmit/receive unit (WTRU) transmits a PRACH preamble. The WTRU attempts to detect a response to the PRACH preamble during a time window. This procedure is not particularly adapted for non-terrestrial communications.

SUMMARY

Systems, methods, and devices for random access to a communications network by a WTRU. In some implementations, the WTRU receives random access response (RAR) configuration information. The WTRU determines a time offset for a RAR window, based on a minimum round trip time (RTT) between the WTRU and a non-terrestrial network device. The WTRU determines a length of the RAR window. The WTRU transmits a PRACH preamble to the non-terrestrial network device. The WTRU monitors a physical downlink control channel (PDCCH) from the non-terrestrial network device during the RAR window based on the time offset and the length of the RAR window.

