Optimal Filter Selection for MIMO F-OFDM Systems in 5G Wireless Communication

Strong demand for mobile broadband cellular systems has boosted the popularity of emerging high-speed modulation technologies such as multiple input multiple output (MIMO) and cyclic prefix orthogonal frequency division multiplexing (CP-OFDM). However, CP-OFDM suffers from some significant drawbacks in 5G networks, including severe out-of-band emissions (OOBE) and poor spectral efficiency. Filtered orthogonal frequency division multiplexing (F-OFDM) has therefore been found to be a good alternative, as it allows to address these shortcomings by relying on digital filtering to eliminate OOBE and improve spectral efficiency. This study focuses on evaluating the performance of MIMO F-OFDM systems and comparing it with the results achieved by MIMO CP-OFDM, with a particular emphasis placed on reducing spectral leakage and improving overall system performance by using various window functions. Six window types, including Hanning, Hamming, Blackman, root raised cosine (RRC), Nuttall, and Blackman-Harris, are investigated. The research aimed to assess the performance of the system in terms of power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER), while using different modulation schemes, i.e. QPSK, 16QAM, 64QAM, and 256QAM, over Rayleigh fading and AWGN channels. Simulation results show that the proposed window filter (Nuttall-Blackman-Hanning) significantly reduces OOBE while maintaining efficient spectral performance. The findings demonstrate that MIMO F-OFDM with the proposed filters achieves better spectral efficiency and reliability, making it a promising candidate for 5G applications requiring high data rates, low latency, and robust signal integrity.