Performance Analysis of OFDM System Using Non-conventional Transform and Non-conventional Mapping Schemes over Rayleigh Channel

Abstract

ABSTRACT

High data rate wireless transmission is required to meet the rapidly increasing demands for mobile communications. Fast Fourier transform (FFT)-OFDM has drawn much attention due to its simple implementation and robustness against frequency-selective fading channels. Recently, the advantages of the discrete cosine transform (DCT)-based OFDM have come to the light. In this paper, performance of the conventional FFT-OFDM system is compared with non-conventional DCT-OFDM in terms of bit error rate (BER). These performances have been compared in AWGN channel and in multipath environment by considering Rayleigh channel. Performance has been compared with conventional mapping schemes such as BPSK, QPSK and non-conventional mapping schemes such as π/4 DQPSK. Simulation results show that DCT based schemes give better error performance in comparison of FFT based schemes. Particularly, in Rayleigh fading channel DCT-based technique using non-conventional mapping schemes outperforms the conventional mapping schemes.

Keywords: Bit- error rate (BER), Discrete Cosine Transform (DCT), Fast Fourier Transform (FFT), Orthogonal Frequency Division Multiplexing (OFDM), Multicarrier  Modulation (MCM).