Self-recovering multirate equalizers using redundant filterbank precoders

Transmitter redundancy introduced using FIR filterbank precoders offers a unifying framework for single- and multi-user transmissions. With minimal rate reduction, FIR filterbank transmitters with trailing zeros allow for perfect (in the absence of noise) equalization of FIR channels with FIR zero-forcing equalizer filterbanks, irrespective of the input color and the channel zero locations. Methods of exploiting input diversity, blind channel estimators, block synchronizers, and direct self-recovering equalizing filterbanks are derived. The resulting algorithms are computationally simple, require small data sizes, can be implemented online, and remain consistent (after appropriate modifications) even at low SNR colored noise. Simulations illustrate applications to multi-carrier modulation through channels with deep fades, and superior performance relative to the constant modulus algorithm (CMA) and existing output diversity techniques relying on multiple antennas and fractional sampling.