Channel estimation filtering

摘要

The disclosed methods and systems for improved OFDM channel estimation filtering take advantage of the presence of highly correlated adjacent subcarriers to reduce the computational intensiveness of channel estimation filtering. Specifically, baseband signals corresponding to a channel are received. The cyclic prefixes of the baseband signals are removed, and the resulting signal is transformed into the frequency domain, and compensated by a first time offset of the baseband receive signal. Subcarrier signals used to transmit the baseband signal are then extracted. Adjacent subcarriers having channel responses highly correlated to the subcarriers of the channel are identified, and the signal is compensated by a second time offset that corresponds to a minimal angle of the autocorrelation function of the subcarrier and adjacent subcarriers. The resulting signal is filtered to produce filtered channel estimates, using a filter having a filter length corresponding to the number of highly correlated subcarriers that were identified.

主权项

1. A method of obtaining a channel estimate in a receiver, comprising:
receiving a baseband signal having a cyclic prefix, the baseband signal corresponding to a channel; removing the cyclic prefix from the baseband signal; transforming the baseband signal from a time domain to a frequency domain to yield a baseband signal in the frequency domain; compensating the baseband signal in the frequency domain by a first time offset of the received baseband signal to yield a compensated baseband signal in the frequency domain; extracting a subcarrier used to transmit the baseband signal from the compensated baseband signal in the frequency domain to yield a raw channel estimate; determining adjacent subcarriers having channel responses highly correlated to that of the subcarrier; compensating the raw channel estimate in the frequency domain by a second time offset to yield a compensated raw channel estimate, where the second time offset corresponds to a minimal angle of the autocorrelation function of the subcarrier and the adjacent subcarriers; and filtering the compensated raw channel estimate with a filter to yield the filtered channel estimate, wherein a filter length of the filter corresponds to a total number of the subcarrier and the adjacent subcarriers; wherein the filtering operation comprises: filtering, in frequency domain, the compensated raw channel estimate using a linear filter; and interpolating the compensated raw channel estimate using an interpolation filter.