Patent ID: 7039140
Filing Date: 2006-05-02
Classification: H04L

Abstract:
1. A synchronization method for data demodulation in an OFDM radio receiver, comprising the steps of: sampling and measuring an OFDM radio transmission to obtain a series of received-signal samples that represent a short preamble, a long preamble, a long preamble guard interval (GI), and a first long preamble, respectively; computing an inner product of vectors comprised of samples x(n), x(n−1), . . . , x(n−1−N) and x(n), x(n+1), . . . , x(n+N−1) of said received-signal samples and computing the magnitude squared of a coherent and non-coherent combination determined by: assuming an index of the maximum of the result of the combination is the index of the start of the first long preamble; subtracting a corresponding number of samples from the result of the combination to find a first received-signal sample of said long preamble guard interval (GI); and identifying said first received-signal sample of said long preamble GI to synchronize any data demodulation of subsequent parts of said OFDM radio transmission, wherein n is an integer identifying the n'th sample, x(n), of the vectors, N is an integer having a value determining the number of samples in the vectors, and k is an integer having a value varying from 0 to N−1.