Low complexity FBMC for wireless MIMO systems

Filter Bank Multicarrier (FBMC) has become popular as an alternative to OFDM (Orthogonal Frequency Division Multiplexing). However, current FBMC systems found in the literature are not as compatible with MIMO (Multiple Input and Multiple Output) as OFDM is. This is due to the presence of inherent self-interference in current FBMC structures. Current literature uses maximal spectrally efficient waveforms, which have high interference among sub-carriers, thereby requiring complex post-processing in MIMO systems. In this work, we relax the spectral efficiency and show quantitatively that both the interference and out of band ripple energy can be decreased. We analyze this interference and its effects on different modulations at various SNR (Signal to Noise Ratio) values. We observe that the interference effect is more dominant at high SNR and affects higher order modulations more significantly. Reducing the interference enables near-orthogonal FBMC designs for practical SNR values and higher order modulations while still retaining MIMO receiver structures with low design complexity. We also show that error correcting codes can mitigate the effects of this interference. In this paper, first we compare our proposed FBMC system with OFDM and then with Filtered OFDM, one of the leading waveform candidates for 5G. Our simulations reveal that there is less than 1 dB gap between OFDM and FBMC having 84% and 97% spectral efficiencies respectively, using a 4 × 4 MIMO-VBLAST for 64-QAM at 30 dB SNR. Also, a comparison with Filtered OFDM system reveals that the proposed FBMC system is computationally more efficient for 5G systems. © 2021 Elsevier B.V.