Patent ID: 7764593
Filing Date: 2010-07-27
Classification: H04J,H04L

Abstract:
1. A method of configuring a downlink signal in an orthogonal frequency division multiplexing access-frequency division duplexing (OFDMA-FDD) mobile communication system, said method comprising: (a) configuring a downlink frame with a plurality of symbols; and (b) for each symbol, allocating a plurality of traffic subcarriers and a plurality of pilot subcarriers, said pilot subcarriers being distributed with respect to both time and frequency, a part of said pilot subcarriers being reference for a mobile station to perform time synchronization, frequency synchronization, and cell search; wherein the pilot subcarriers are distributed at regular intervals with respect to time, and are distributed at irregular intervals with respect to frequency; said system comprises a plurality of cells; the pilot subcarriers are allocated to the cells according to proper position sets of pilot subcarriers so that the pilot subcarriers in adjacent cells are not superimposed; when the number of cells is greater than an available number of the proper position sets, the pilot subcarriers are allocated so as to minimize a number of pilot subcarriers that are superimposed in non-adjacent cells; the cells are divided into groups of cells; a predetermined number of said pilot subcarriers are allocated for each cell, said predetermined number being generated by dividing the number of subcarriers by the number of cells; as to insufficient pilot subcarriers, part of said pilot subcarriers being allocated for each cell are allocated to the cells which have the same position in different groups; and the proper position set K where g is a prime number that satisfies Nu/Np≧g; Nu is the number of subcarriers; Np is the number of subcarriers included in each cell group; G is the number of cells in each cell group, wherein G<g; K is a set of subcarriers f h v(k) is a specified pseudo random sequence having values from 0 to (g−1); and j is a valued from 0 to (G−1).