Patent ID: 6459679
Filing Date: 2002-10-01
Classification: H04L

Abstract:
A method of synchronizing an OFDM receiver to an OFDM signal comprising the steps of:(a) receiving an OFDM reference symbol before user data OFDM symbols, the OFDM reference symbol having sub-symbol signals at only random, even-numbered sub-carriers and having no signals at any other even-numbered sub-carriers and all odd-numbered sub-carriers in the frequency domain, and the first half of the symbol having the same characteristics as the remaining half in the time domain; (b) obtaining OFDM digital signal samples rk by sampling the received OFDM reference symbol and converting the OFDM reference symbol samples into digital signals; (c) obtaining a predetermined timing metric for each of the OFDM signal samples rk according to the time-domain characteristics of the reference symbol, and detecting the point in time at which the power of the timing metric is maximum as the starting point of a symbol/frame of the OFDM signal; and (d) correcting for the offsets of sub-carrier frequencies that are less than the frequency spacing between two adjacent sub-carriers by obtaining a frequency offset from the phase of the timing metric at the detected symbol/frame starting point, and correcting for the offsets of sub-carrier frequencies that are greater than the frequency spacing between two adjacent sub-carriers by obtaining the value which maximizes the power metrics according to the frequency-domain characteristics of the reference symbol.