Abstract: In this paper the performance analysis of OFDM architecture with and without equalization is performed by using three efficient coherent modulation techniques which are BPSK, QPSK and M-QAM modulation. Whole analysis is implemented over PON-OFDM model with Rayleigh fading channel having AWGN noise. Then the performance comparison is done with three modulations with and without equalization. Here the OFDM architecture is used to reduce noise (can be inter-symbol interference) which is the most important loss or attenuation in optical signals, thus reshaping and equalization (filtering) is performed. The simulation over BPSK, 16-QAM, 32-QAM and QPSK signals is implemented over Rayleigh and AWGN channel thus the effect of channel signal fading due to noise is observed in addition with equalization to obtain an accurate value of Bit Error Rate BER. Thus the explanatory results of BER determine the efficiency of BPSK, QPSK and M-QAM technique with respect to OFDM.

Keywords: BPSK, QPSK, M-QAM, BER, SNR, OFDM, AWGN, PON, CP, ZP, CO, ONU, OLT, ISI etc.