Efficient Implementation of MIMO FBMC/OQAM Scheme based on Block Spreading

Filter bank multicarrier (FBMC) was proposed as an alternative approach to cyclic prefix - orthogonal frequency division multiplexing (CP-OFDM). FBMC is considered a promising non-orthogonal waveform due to its very low out of band radiation and high spectral efficiency. Nevertheless, the orthogonality constraint for FBMC/OQAM is relaxed being limited only to the real field which causes intrinsic interference. The presence of this interference leads to incompatibility between some well-known multiple-input and multiple-output (MIMO) schemes and FBMC/ offset quadrature amplitude modulation (OQAM). From this perspective, we proposed in this paper an efficient implementation for FBMC/OQAM based on block spreading to restore the complex orthogonality to enable applying MIMO with FBMC/OQAM. The proposed scheme uses a discrete Haar transform (DHT) to enable low computational complexity. The performance of proposed approaches has been investigated and compared with CP-OFDM under three MIMO schemes, as space-time block coding (STBC) Alamuoti schemes, spatial multiplexing with zero-forcing (ZF), and maximum likelihood (ML) detection schemes. The simulation results show that the proposed schemes enable to apply of the MIMO schemes with FBMC with almost the same performance and complexity as CP-OFDM.