1. A receiver detecting a sequence used in a received (Rx) signal in a mobile communication system using orthogonal frequency division multiplexing (OFDM), the receiver comprising:a radio frequency (RF) module including a receiver receiving the Rx signal from a transmitter; and
a processor connected to the radio frequency module and detecting the sequence used in the Rx signal,
wherein the sequence used in the Rx signal is generated by using a Zadoff-Chu sequence having one of indexes contained in a predetermined index set,
wherein the predetermined index set comprises a first index and a second index, and
wherein a sum of the first index and the second index corresponds to a length of the Zadoff-Chu sequence.