Papr reduction in OFDM & MC-CDMA system using nonlinear companding techniques

High peak to average power ratio (PAPR) of the transmitted signal is a major drawback of OFDM and MC-CDMA systems. In this paper various existing nonlinear companding transforms are analyzed and compared for the reduction of peak to average power ratio in OFDM and MC-CDMA systems. Nonlinear companding transforms transform the amplitude or power of the original signals into uniform distribution, which can effectively reduce the PAPR for different modulation formats and subcarrier sizes without any complexity increase and bandwidth expansion. Nonlinear companding technique adjust both large and small signals and can keep the average power at the same level. Nonlinear companding transforms can significantly improve the performance of OFDM and MC-CDMA system including bit-error-rate and PAPR reduction.