Methods, apparatuses, systems, etc. for, and/or for use in connection with, performing initial access in a non-terrestrial network (NTN) of a communications system. Among such methods is a method that may be implemented in a wireless transmit/receive unit (WTRU) and may include any of receiving, from the NTN, differential delay information and physical random access channel (PRACH) configuration information indicating a set of preambles and a PRACH occasions configuration; determining a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, based on the differential delay information; selecting a preamble from a group of the preambles allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.