Improved Performance of Companded OFDM System using Non Symmetric Approach

Companding transforms signals useful under assumption of infinite bandwidth. Under band limited conditions Out of band radiation (OBR) parameter filters out. So bandwidth is a factor that decides the filtering out OBR on the performance of companded OFDM systems. As a result filtering becomes essential under band limited conditions in turn this does deteriorate the system performance significantly. In this paper method proposed to overcome the performance degradation of various aspects on linear/nonlinear companders using for digital modulation techniques, method called non linear symmetric scheme based on the use of curve fitting method to find out a suitable polynomial to be used for decompanding at the receiver in sufficient bandwidth conditions. This method indeed improves the performance in comparison in various aspects like PAPR, BER, OBR, functions of FFT, IFFT etc. to existing symmetric methods when filtering is necessary for band limited conditions.