HYBRID PAPR REDUCTION TECHNIQUES IN OFDM AND MIMO-OFDM SYSTEM FOR DIFFERENT MODULATION SCHEMES

Abstract

Orthogonal frequency division multiplexing (OFDM) is the most prominent multicarrier modulation scheme for existing as well as next generation wireless communication system. To meet the growing need for higher data rate with lower bit error rate, OFDM system has been combined with multiple input multiple output (MIMO) system which employs multiple antennas both at transmitter and receiver. In spite of having wide range of applications and advantages, the major drawback of OFDM system is having high peak to average power ratio (PAPR). For transmitting the signals with high PAPR, highly expensive high power amplifir is required with large dynamic range. Moreover, it may cause nonlinear distortion. This drawback makes the overall OFDM system less effective. Hence reduction of PAPR in OFDM system is a major challenge for designing effiient and cost effective wireless system. To solve the impediment, various PAPR reduction techniques have been proposed which may provide signifiant PAPR reduction but adversely affect the BER performance. To overcome the limitations of existing techniques, various hybrid PAPR reduction techniques are proposed by combining two existing techniques so that the advantages of both the PAPR reduction techniques can be utilized. This thesis work aims to analyze the performance of the existing PAPR reduction techniques and propose a new hybrid PAPR reduction technique from the combination of the most prominent existing PAPR reduction techniques for both OFDM and MIMO-OFDM system. The contribution of the proposed hybrid PAPR reduction technique is determined by comparing the performance with the existing PAPR reduction techniques. However, it is observed that the proposed hybrid PAPR reduction technique provides almost 88% PAPR reduction in OFDM and 82% PAPR reduction in MIMO-OFDM system, which is much improved than the existing PAPR reduction techniques.