Least squares channel identification for OFDM systems

摘要

An OFDM system generates a channel estimate in the time domain for use in either a frequency domain equalizer or in a time domain equalizer. Preferably channel estimation is accomplished in the time domain using a locally generated reference signal. The channel estimator generates an initial estimate from a cross correlation between the time domain reference signal and an input signal input to the receiver and generates at least one successive channel estimate. Preferably the successive channel estimate is determined by vector addition (or subtraction) to the initial channel estimate. The at least one successive channel estimate reduces the minimum mean square error of the estimate with respect to a received signal.

主权项

1. A receiver for OFDM signals, comprising:
an initial channel estimator that generates, responsive to one or more pilot subchannels within a received OFDM symbol comprising pilot and data subchannels, an initial time domain channel estimate of a channel over which the received OFDM symbol was transmitted; a time domain channel estimator coupled to receive the initial time domain channel estimate, the time domain channel estimator responsive to the initial time domain channel estimate to generate a further time domain channel estimate that more accurately characterizes the time domain channel over which the received OFDM symbol was transmitted, wherein the time domain channel estimator generates a reduced dimension representation based on the initial time domain channel estimate prior to determining the further time domain channel estimate; and a frequency equalizer responsive to the further time domain channel estimate to output an equalized signal responsive to the received OFDM symbol.