Patent ID: 7421029
Filing Date: 2008-09-02
Classification: H03H,H04L

Abstract:
1. A method for receiving at a receiver having a variable filter a transmitted signal that includes a periodic training signal and a data signal comprising OFDM symbols having cyclic guard intervals, the periodic training signal comprising a succession of substantially identical training pulses, the method comprising: (a) receiving and sampling the transmitted signal at the receiver to produce a digital complex baseband signal; (b) filtering the digital complex baseband signal with the variable filter; (c) detecting the periodic training signal in the filtered digital complex baseband signal, wherein each of the training pulses of the periodic training signal includes a linearly-frequency-modulated (LFM) pulse; (d) upon detecting the periodic training signal, computing a number of training signal samples remaining until the data signal commences to synchronize decoding of the data signal; (e) determining a desired channel impulse response based on the detected periodic training signal, comprising estimating a periodic convolution of an undistorted training pulse with an initial channel impulse response for use in determining the desired channel impulse response; (f) calculating filter coefficients required by the variable filter to achieve the desired channel impulse response; and (g) adjusting the variable filter according to the calculated filter coefficients.