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Analysis of OFDM System by Comparing Different PAPR Reduction Schemes

Harish Kumar Pal, Garima Bhardwaj, Anurag Singh

Orthogonal Frequency Division Multiplexing (OFDM) is an efficient method of data transmission for high speed, high spectral efficiency and robustness to multipath fading channel in communication systems. However, the dominating drawbacks of OFDM system are due to high Peak to Average Power Ratio (PAPR) and Interchannel interference (ICI).High PAPR of the transmitted signals consist of large number of independent subcarriers, as a result of which the amplitude of such a signal can have high peak values which requires a highly linear power amplifier (PA) and because of nonlinear operation there is inter-modulation between the different carriers and introduce additional interference into the system. This additional interference leads to an increase in the bit error rate (BER) of the system. One way to avoid such non-linear distortion and keep low BER is to force the amplifier to work in its linear region. Unfortunately such solution is not power efficient and thus is not suitable for wireless communication because Power amplifiers with large linear range are bulky, costly and difficult to manufacture. Hence a high PAPR in the system design should be restricted. And with ICI the signal degrades heavily which is because of change in frequency known as frequency offset. There are two main reasons for frequencies offset which are frequency mismatch between transmitter & receiver and Doppler Effect. The high PAPR and undesired ICI degrade the performance of OFDM system therefore several methods have been proposed for the reduction of high PAPR and ICI. This paper analyses different PAPR reduction methods and makes a comparison among them using CCDF curves and MATLAB coding.