Patent ID: 7263058

Claim:
A preamble sequence generating method in a BWA (Broadband Wireless Access) communication system using OFDM (Orthogonal Frequency Division Multiplexing) for frequency synchronization and channel estimation, comprising the steps of: generating at least one ARM (Aperiodic Recursive Multiplex) code by outputting a third sequence by multiplying a first sequence having a first length and a second sequence having the first length containing alternating +1s and −1s, outputting a fourth sequence by time-multiplexing the first sequence and the third sequence, and resetting the fourth sequence as the first sequence until an intended length of the ARM code is achieved; mapping the samples of the ARM code to sub-carriers equally distributed in a frequency band; and generating a preamble sequence by performing IFFT (Inverse Fast Fourier Transform) on sub-carriers containing ARM code samples remaining from deleting a predetermined number of ARM code samples from the ARM code samples, a reference component representing a DC component, and null components inserted between the remaining ARM code samples and the reference component, wherein the preamble sequence is used for frequency synchronization and channel estimation.