Patent ID: 7702028

Claim:
A method of transmitting a preamble in an orthogonal frequency division multiplexing (OFDM) communication system using Q transmit antennas, comprising the steps of: (1) generating a base preamble sequence including a cyclic prefix (CP) and an orthogonal sequence; and (2) generating a preamble sequence for each of the Q transmit antennas from the base preamble sequence by rotating the orthogonal sequence of the base preamble sequence by a different predetermined number of symbols, and at least twice transmitting the generated preamble sequences from the Q transmit antennas, such that the preamble sequence transmitted from a kth antenna is (−1) (PS−1) S(t−(k−M−1)T/M), where M is a predetermined number, k is greater than M, S(t) is the orthogonal sequence, T is the period of the orthogonal sequence, and PS is an index indicating a transmission period of the preamble sequence.