Chapter 12. FBMC Channel Equalization Techniques

International audiencebroadband wireless communications is their robustness to multipath propagation channels, stemming from the fact that they divide the channel spectrum into very narrow subbands, and, in the extreme case, no frequency selectivity, i.e., only flat fading, is observed in each of them. For an increased spectral efficiency, most practical MCM schemes have their subbands overlapped in frequency. In Cyclic Prefix Orthogonal Frequency-Division Multiplexing (CP-OFDM), Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI) can be completely removed if the Cyclic Prefix (CP) is at least as long as the channel delay spread. Thus, at the expense of reducing the spectral efficiency due to the CP redundancy, the subchannels corresponding to the different subbands are completely decoupled. The equalization in CP-OFDM then becomes trivial and can be performed by a single complex multiplication per subcarrier, giving rise to the so-called single-tap equalizer.CP-free transmission is possible in systems based on FilterBank MultiCarrier with Offset-QAM subcarrier modulation (FBMC/OQAM), but, on the other hand, more sophisticated channel equalizers may be necessary, for mildly and highly frequency selective channels. This chapter reviews a number of equalization methods for such systems, covering both classical solutions and more recent advances, of the training-based or blind type