The Ofdm System In The Peak To Average Power Ratio

Orthogonal frequency division multiplexing (OFDM) is an attractive technique for high-bit-rate transmission in a radio environment. By dividing the total bandwidth into many orthogonal narrow subchannels, the effects of multipath delay spread can be minimized.Unfortunately, a central disadvantage of OFDM is potentially high peak-to-average power ratio (PAPR) values, which can result in significant distortion when transmitted through a nonlinear device, such as a transmitter power amplifier. Clipping could be an effective technique for PAPR reduction, but it degrades the bit-error-rate (BER) performance. In this thesis we analyze the conventional Clipping and Partial Transmit Sequences (PTS) methods, then propose a hybrid algorithm to get a better performance of BER by using the PTS method before Clipping. Next, in order to provide good performance of PAPR with lower complexity by PTS method, two new techniques are proposed: Adaptive Dual Layered Phase Sequencing (ADLPS) and Adaptive PTS with Genetic Algorithm (APTS_GA) methods. Based on simulation results, both of the methods can improve the performance with lower complexity.