1. A method for selectively operating a duplex mode by a communication device in a wireless communication system, the method comprising:operating in an Half Duplex Radio (HDR) mode in a resource containing a physical channel or a signal used for an initial access prior to an Radio Resource Control (RRC) connection; and
operating in a Full Duplex Radio (FDR) mode after the initial access,
wherein the resource contains a resource for receiving a Physical Random Access Channel (PRACH), and
wherein a prescribed frequency band contiguous to the resource for receiving the PRACH is configured as a band capable of performing downlink transmission only.