Performance Analysis of SIMO-OFDM Wireless Communications Based on MRC Technique over AWGN and Frequency Selective Channels

الملخص

The analysis of bit error rate (BER) performance of single input multiple output (SIMO) combined with orthogonal frequency division multiplexing (OFDM) wireless communication system exploiting maximum ratio combining (MRC) technique over additive white Gaussian noise (AWGN) and frequency selective channels are studied. SIMO system can be implemented by exploiting maximum ratio combiner (MRC) at the receiver side. MRC provides full spatial receive diversity gain which improves system quality of service (QoS) and as a result combatting a fading due to multipath propagation. Moreover, OFDM offers significant advantages such as bandwidth efficiency and its robustness against multipath delay spread. The level of robustness against the multipath delay spread can be further increased by selecting the length of the cyclic prefix (CP) more than or equal to channel length (CL) (number of multipaths). Adding CP eliminates or minimizes inter-symbol-interference (ISI). In contrast, when CL greater than CP leads to error floor at high SNR. This paper presents simulation BER performance of the combination of SIMO with OFDM systems. The simulation BER performance of conventional single input single-output (SISO-OFDM) one by one wireless system compared with SIMO-OFDM systems one by two, and, four receive antennas, with quadrature phase shift keying (QPSK) digital modulation scheme, over AWGN channel and frequency selective fading channel. The results confirm that the performance of SIMO-OFDM is significantly improved compared with conventional SISO-OFDM system. Moreover, the results also confirm that when CL greater than CP leads to error floor at high SNR. Furthermore, SIMO-OFDM (1Tx, 4Rx) improves BER performance significantly and mitigates ISI effectively.