Performance of Ofdm Multiplexing Transmission Using Different Digital Modulation Schemes

A detail analysis of the performance of an orthogonal frequency division multiplexing (OFDM) transmission with different digital modulation techniques such as BPSK, QPSK and QAM has been carried out. BER performance has been determined for Additive white Gaussian Noise (AWGN) channel. The simulation results for the performance of OFDM using different digital modulation schemes BPSK, QPSK and QAM are determined for comparing their performances. It is observed that the OFDM multiplexing shows 4dB improvement in BER performance for QAM modulation compared to that of QPSK modulation. Similarly QPSK modulation techniques exhibits 2dB improvement in the performance compared to BPSK modulation. It is observed that OFDM multiplexing indicates a gradual improvement in BER performance with higher digital modulation techniques. The simulation results are presented and discussed in the paper. INTRODUCTION: The key challenge faced by future wireless communication systems is to provide high-data-rate wireless access at high quality of service (QoS). Combined with the facts that spectrum is a scarce resource and propagation conditions are hostile due to fading and interference from other users. This requirement calls for means to radically increase spectral efficiency and to improve link reliability. The wireless channel is distinct and much more unpredictable than the wire-line channel because of factors such as multipath and shadow fading, doppler spread, and delay spread or time dispersion. OFDM is expected to be used in future broadcasting and wireless LAN (WLAN) systems. IEEE 802.11a is the technology that used OFDM concept [1]. Since wireless technologies become a very high demand nowadays, OFDM has been chosen to be a subject study for different digital modulation schemes [2].