Provided herein is design of early data transmission in wireless communication system. An apparatus for a user equipment (UE) includes a processor configured to: encode a physical random access channel (PRACH) sequence from a plurality of PRACH sequence for transmission via a PRACH to perform a random access procedure, wherein indication of support of early data transmission (EDT) that is transmitted during the random access procedure is based on at least one of the plurality of PRACH sequences, higher layer signaling, PRACH resources, PRACH formats, and a payload from the UE; and send the PRACH sequence to a radio frequency (RF) interface; and the RF interface to receive the PRACH sequence from the processor. Design of random access response (RAR) is also disclosed herein.