A method of determining a cell identity in a wireless communication system is disclosed. The present invention includes the steps of obtaining a segment ID and a sequence index from an SA-preamble (secondary advanced preamble) sequence received from a base station and determining the cell identity using the segment ID and the sequence index. In this case, the cell identity corresponds to one SA-preamble sequence and a cell identity adjacent to the cell identity corresponds to an SA-preamble sequence having a complex conjugate relation of the one SA-preamble sequence.