Performance evaluation of MC-CDMA system for the next generation wireless networks

Abstract

Rising demand for system capacity, higher data rate and multimedia services brought to light the concept of Multi Carrier Code Division Multiple Access (MC-CDMA) technique. It is basically the fusion of Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM) schemes. As a result, MC-CDMA carries the advantages of both, CDMA and OFDM. Here, CDMA increases the efficiency of bandwidth utilization and OFDM helps to reduce Inter Symbol Interference (ISI) as well as multipath fading. As MC-CDMA is based on OFDM, in this paper, the performance of OFDM system is studied as a prerequisite to analyzing MC-CDMA system. Then the Bit Error Rate (BER) performance of the MC-CDMA system is observed for different modulation techniques using MATLAB. The observations are carried out over Rayleigh fading channel with Additive White Gaussian Noise (AWGN). Walsh-Hadamard (W-H) code is used for spreading, as it reduces the Multiple Access Interference (MAI). It is seen that BPSK and QPSK show better performance in terms of BER. Finally, it is observed that, due to Multi User Interference (MUI) and Multipath Interference (MPI), the performance of MC-CDMA degrades when the number of users in a channel is increased.