Equalization: Analysis of MIMO Systems in Frequency Selective Channel

Due to the increased demand of wireless communication systems because of the features of the system which provides a wide coverage, high throughput and reliable services, the MIMO systems communication has come into existence. Features provided by these systems ensure the improved system coverage and increased data transmission rate by considering multiple numbers of transmitter and receiver antennas. In this paper, we are considering the equalization; a filtering approach that minimizes the error between actual output and desired output by continuous updating its filter coefficients for Rayleigh Frequency selective fading channel. We concluded that MMSE and ZF give the worst performance in Rayleigh frequency selective channel as compare to Rayleigh Flat fading Channel [35] due to a constant BER for large SNR’s. We have also observed that the successive interference methods provide better performance as compare to others, but their complexity is high. ML provides the better performance in comparison to others and BER doesn’t remain constant for a large SNR in this case. Simulation results shows that ML equalizer with BPSK gives better performance as compare to QPSK. Finally we concluded that Sphere decoder provides the best performance. Keywords-Quadrature Amplitude Modulation (QAM); Quadrature Phase Shift Key (QPSK); Binary Phase Shift Key (BPSK); Minimum mean-squared error (MMSE); Maximum likelihood (ML); Bit error rate (BER); Inter-symbol interference (ISI); Successive-interference-cancellation (SIC); Sphere Decoder (SD); Zero Forcing (ZF).