RACH OPTIMIZATION FOR NB-IOT NTN GSO

This disclosure provides methods, components, devices and systems for optimized RACH procedures in NTNs including NB-IoT. A UE performs in an NTN one or more of a first or second procedure in an idle mode, or a third procedure in a connected mode. In the first procedure, the UE considers a number of RAPIDs in msg2, and if the number meets a threshold, the UE applies a backoff to delay sending msg1. In the second procedure, if the UE fails to decode msg2 or msg4 after transmitting msg1, the UE applies a backoff before performing subsequent RACH. In the third procedure, following a failure to receive an uplink grant when monitoring a USS and after transmitting msg1 for a SR, the UE continues monitoring the USS for the grant until the start of a RAR window. If the uplink grant is received during this time, the UE cancels msg2 monitoring.