Performance Analysis of PAPR Reduction Techniques In OFDM System

Abstract

High data rate with high bandwidth efficiency and low power consumption are some of the requirements that the modern wireless communication systems 3G and 4G have to meet for offering new high class services to be distributed to the customers. In wireless communication, signals are mainly damaged by frequency selective fading and multipath delay spreading. The solution to all these problems is to use a multicarrier system; Orthogonal Frequency Division Multiplexing (OFDM) is an example of it. OFDM is a bandwidth efficient multicarrier modulation where the available spectrum is divided into subcarriers, with each subcarrier containing a low rate data stream. However, OFDM has one major drawback of high peak-to-average power ratio (PAPR) which can result in poor power efficiency, degradation in bit-errorrate (BER) performance, and spectral spreading. Firstly this thesis investigates the problem of high PAPR in OFDM systems and then it presents and compares available PAPR reduction techniques. Comparison result shows that no specific PAPR reduction technique is the best solution for all multicarrier transmission systems. Selection of technique is varied according to various system requirements. Secondly it implements two existing distortionless techniques such as Partial Transmit Sequenece (PTS) Technique and Selected Mapping(SLM) Technique. Simulation results show that SLM gives better performance than PTS. Finally A new PAPR reduction method is proposed which is a combination of SLM and PTS technique. The proposed technique generates the alternate OFDM sequences based on combining all possible combinations of different phase shifts and selects the one which is having minimum PAPR. This Hybrid Technique gives PAPR reduction around 6.8 dB which is far better compared to SLM and PTS technique. As a conclusion, the proposed technique described offer new solution to the problem of high PAPR in OFDM systems, with improvement in PAPR reduction performance compared to existing techniques.