Transmitter redundancy introduced using filterbank precoders generalizes ex
isting modulations including OFDM, DMT, TDMA, and CDMA schemes encountered
with single- and multiuser communications. Sufficient conditions are derive
d to guarantee that with FIR filterbank precoders FIR channels are equalize
d perfectly in the absence of noise by FIR zero-forcing equalizer filterban
ks, irrespective of the channel zero locations. Multicarrier transmissions
through frequency-selective channels can thus be recovered even when deep f
ades are present. Jointly optimal transmitter-receiver filterbank designs a
re also developed, based on maximum output SNR and minimum mean-square erro
r criteria under zero-forcing and fixed transmitted power constraints. Anal
ytical performance results are presented for the zero-forcing filterbanks a
nd are compared with mean-square error and ideal designs using simulations.