Power controlled MC-CDMA in cellular communication systems

Abstract

In this paper, a power controlled Multi Carrier Code Division Multiple Access (MC-CDMA) system is evaluated to combat multipath fading channel in cellular communication systems. MC-CDMA is developed to mitigate the effect of frequency selective fading channel, while power control is proposed to combat Rayleigh fading channel fluctuation. Computer simulation is conducted to evaluate the performance of MC-CDMA as well as for the power control in terms of bit error rate (BER) as a function of bit energy to interference density ratio (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ). The performance of MC-CDMA is evaluated using both orthogonal Hadamard and random codes in Additive White Gaussian Noise (AWGN) channel. CDMA power control performance is evaluated to see the effect of fading rate relative to the power control rate for fixed-step and variable step algorithms. The results show that the performance of MC-CDMA is independent of the number of users when orthogonal Hadamard codes is used, but degrades with increasing number of users for the random codes. The effect of users' mobility on power control performance shows that variable step algorithm outperforms the fixed step algorithm for high fading rates, but shows a similar performance for low fading rates environments.