PAPRs reduction in MC-CDMA signal based on a modified phase approach

A significant problem in multicarrier communication systems is the necessity to reduce the value of PAPR (Peak-to-Average Power Ratio) of the transmitting signal. In this paper we study the effect of different system parameters on PAPR and ultimate BER in a MC-CDMA system. In this study we consider fading channel as well as the nonlinearity of transmitter's amplifier to show how the control of the PAPR in different approaches can actually affect on the overall quality of the received signal. We propose a new method of PAPR reduction in MC_CDMA system which is based on phase perturbation after spreading process. This method follows the fact that the PAPR of the MC-CDMA signal is highly dependent on the related phase of the subcarriers. In this way we actually separate the spreading part from the PAPR control process and would be able to select the most appropriate code for each part separately. Simulation results show that the proposed scheme achieves significant improvement of the PAPR and quality of received signal without increasing the complexity of the receiver.