Filterbank Multicarrier-QAM for MIMO systems

Filterbank Multicarrier (FBMC) has been proposed as an alternative to Orthogonal Frequency Division Multiplexing (OFDM) in the multicarrier modulation scenario. One of the many advantages of OFDM is its compatibility with Multi-Input Multi-Output (MIMO) systems. One disadvantage of using FBMC is the need for multi-tap per subcarrier equalization, unlike the single tap equalization in OFDM. There has been research in the field of MIMO which suggest a channel frequency flattening phenomena, which has been mentioned in literature as channel hardening, self equalization and so on. When FBMC is combined with MIMO, the equalization complexity required is seen to be reduced. There are many challenges combining FBMC and MIMO. FBMC-Offset Quadrature Amplitude Modulation (OQAM) is proposed as a modulation technique to replace OFDM. We show that there are many practical difficulties for FBMC-OQAM-MIMO. So we propose a FBMC-QAM-MIMO technique. We look at many disadvantages of FBMC-OQAM that is already in literature as well as the difficulties that we have observed. We explain how FBMC-QAM can overcome these difficulties. Channel flattening in FBMC-QAM-MIMO is also looked at in detail. It is explained by effective impulse response of a MIMO channel. We look at its performance when one tap equalization is used. Performance of one tap equalization for different waveforms is compared with OFDM.