Patent ID: 7773499

Claim:
An apparatus comprising: receive electronics operative to wirelessly receive and digitize a wirelessly transmitted OFDM data packet that includes a preamble having a known first symbol and a known second symbol, the receive electronics having an output outputting a set of received data samples, and a Fourier transformer having an input coupled to the output of the receive electronics, and an output, and operative to determine the Discrete Fourier Transform of the set of received data samples, the Discrete Fourier Transform of the received data samples forming a set of subcarriers corresponding to the set of received data samples, a switch unit having an input coupled to the receive electronics and accepting a function of a first set of received samples that corresponds to the first known symbol or of a second set of received samples that corresponds to the second known symbol, and having a first output and a second output, the switch unit operative to connect the input to the first output when the input is accepting the function of the first set of received samples and to connect the input to the second output when the input is accepting the function of the second set of received samples; a memory unit coupled to the first output of the switch unit, the memory operative to store the function of the first set of received samples that corresponds to the first known symbol; an averaging unit having a first input coupled to the memory and a second input coupled to the second output of the switch unit, and operative to determine the average of the function of the first and second sets of received samples; a factoring unit having an input coupled to the output of the Fourier transformer, the factoring unit having an output producing a set of rough channel estimates, the factoring unit operative to factor out the set of subcarriers corresponding to the first known symbol or the second known symbol from a set of subcarriers that are the transform of a first or second set of received samples that respectively correspond to the first or second known symbol; and a smoothing filter having an input coupled to the output of the factoring unit, the smoothing filter operative to determine smoothed channel estimates, such that the smoothed channel estimate for a particular subcarrier includes a contribution from channel estimates of one or more subcarriers that are nearby the particular subcarrier to take advantage of correlation that may exist between the particular subcarrier's channel and the channels of the one or more nearby subcarriers.