Patent ID: 7590184
Filing Date: 2009-09-15
Classification: H04L

Abstract:
1. A method for generating a coarse timing for an orthogonal frequency division multiplexed (OFDM) complex valued sample stream, comprising: capturing, using a receiver, a portion of the OFDM complex valued sample stream; autoconvolving, using the receiver, the portion of the OFDM complex valued sample stream to generate an autoconvolved portion; determining, using the receiver, a presence of a preamble in the OFDM complex valued sample stream if a peak is detected in the autoconvolved portion; if the presence of the preamble is determined, selecting, using the receiver, one of a plurality of peaks in the autoconvolved portion having greatest energy among the plurality of peaks; identifying, using the receiver, at least three time instants relative to the selected one of the plurality of peaks; autoconvolving, using the receiver, at least three identical size portions of the OFDM complex valued sample stream beginning at each of the at least three time instants; selecting, using the receiver, a time instant out of the at least three time instants that is earliest in time and has a peak in the autoconvolved identical size portion; identifying, using the receiver, at least three refined time instants located at predetermined displacements in time from the selected time instant; for each one of the at least three refined time instants, measuring, using the receiver, autocorrelation between two portions of the OFDM complex valued sample stream; and selecting, using the receiver, one of the at least three refined time instants having lowest phase variance of the autocorrelation as an end of a cyclic prefix of a preamble.