Patent ID: 7580400

Claim:
A method of generating a preamble signal in an orthogonal frequency division multiple access (OFDMA) mobile communication system, the method comprising the steps of: generating, at a Walsh code generator of the OFDMA mobile communication system, a Walsh symbol for a cell identification by combining Walsh codewords having a predetermined length; and generating, at a multiplier of the OFDMA mobile communication system, the preamble signal by multiplying the Walsh symbol by a pseudo noise (PN) symbol having a length identical to a length of the Walsh symbol, wherein the step of generating a Walsh symbol further comprises generating, at a mini Walsh group generator of the Walsh code generator, a mini Walsh group for the cell identification and repeating the mini Walsh group by a predetermined number of times to generate the Walsh symbol, and wherein the step of generating the mini Walsh group comprises determining at least one Walsh codeword index and aligning at least one Walsh codeword corresponding to the determined at least one Walsh codeword index, and the at least one Walsh codeword is selected according to cm=(ac×m+sc) mod p, wherein C of ac and sc is cell ID information of each cell, m is a Walsh codeword interval index of a specific mini Walsh group Wg, ac is a slope of a cell C, sc is an initial Walsh codeword index, and mod is a modulo operation.