Exponentially-modulated filter bank transmultiplexer with fine-coarse adaptive filtering

In this paper we explore filter bank based multicarrier transmission, which has received increasing interest also in wireless communications system development as an alternative to the DFT-based OFDM technique. The odd-stacked low delay exponentially-modulated filter bank (EMFB) transmultiplexer is described. The subfilter biorthogonality condition is distorted in practical transmission channels and we use oversampled (by factor of two) per-subband equalization to recover the data symbols. The fine-coarse normalized least mean square (LMS) algorithm is applied with EMFB-specific modifications. The adaptation speed of the fine-subequalizers are further improved with simple re-initialization procedure. Numerical studies exhibit fast convergence and relatively small residual error in semiblind, decision-directed operation mode.