Performance comparison of Selection Combining diversity receivers for different modulation schemes in OFDM system

This paper deals with the performance analysis (i.e., Symbol Error Rate) of M-ary Phase-shift-keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) to transmit information using Selection Combining (SC) diversity technique over flat Rayleigh communication channel with Orthogonal Frequency Division Multiplexing (OFDM). It is well known that the multipath fading phenomenon is an inherent characteristic of wireless channel. In this paper, it is shown how selection combining diversity scheme enhances reliability in wireless communication by minimizing the channel fluctuations due to fading. The simulation results show that the Signal-to-Noise Ration (SNR) varies between M-PSK and M-QAM but better SNR gain achieved as the number of receiving antenna increases like for two, three and four receiving antennas around 20-27 dB, 22-30 dB, 23-31 dB diversity gains are found respectively.