A method is provided for transmitting a signal from a transmitting end to a receiving end in a wireless communication system. A preamble and the signal are transmitted. A length of the preamble is determined based on a bandwidth of the wireless communication system. The preamble is used for an automatic gain control of the signal. The preamble is transmitted in either a first symbol or a last symbol included in at least one subframe having the signal transmitted therein. A prescribed sample of either the first symbol or the last symbol is nulled by the receiving end and wherein the prescribed sample is included in a guard interval.