Redundant filterbank preceders and equalizers Part II: Blind channel estimation, synchronization, and direct equalization

Transmitter redundancy introduced using finite impulse response (FIR) filte rbank precoders offers a unifying framework for single- and multiuser trans missions. With minimal rate reduction, FIR filterbank transmitters with tra iling 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. Exploiting this simple form of redundancy, blind channel estimators, block synchronizers, and direct self- recovering equalizing filterbanks are derived in this paper, The resulting algorithms are computationally simple, require small data sizes, can be imp lemented online, and remain consistent (after appropriate modifications), e ven at low SNR colored noise. Simulations illustrate applications to blind equalization of downlink CDMA transmissions, multicarrier modulations throu gh channels with deep fades, and superior performance relative to CMA and e xisting output diversity techniques relying on multiple antennas and fracti onal sampling.