A novel simple algorithm to enhance the peak to average ratio of MC-CDMA system

Abstract

The peak to Average Ratio (PAR) or peak to average power ratio (PAPR) is a major drawback of most the multicarrier communications systems. In Orthogonal Frequency Division Multiplexing (OFDM), the PAPR is around 12–13 dB. Also in the Code Division Multiple Access (CDMA), the PAPR is appeared. By combining these two systems (CDMA and OFDM), a good system can be produced which it supports high capacity (multi user multiplexing) with high bit rate. Still the PAPR appeared in the new system because it is a multicarrier system as well. In this work we proposed a novel algorithm to enhance the PAPR which is called 'Half Length Phase Updating ' (HLPU), it is called half because the phase updating will be applied to only half of the IFFT length (N / 2). The HLPU will be predefined both in the transmitter and the receiver, so that, no need to send even one bit of side information from the transmitter to the receiver. This additional block in the system will be inserted before the Inverse Fast Fourier Transform (IFFT) of the Multicarrier Code Division Multiple Access (MC-CDMA) system. The simulation results proved that there is 94.2% reduction in the system complexity and a reduction in the PAPR of around 2 dB has been obtained.