Nonlinearity effect of Power Amplifiers in wireless communication systems

High Power Amplifier in wireless communication systems exhibit nonlinear behavior which causes signal degradation. This is detrimental to the signals that pass through it. It appears in the form of Harmonic distortion, Gain compression, Inter-modulation distortion, Phase distortion, adjacent channel interference, etc. Orthogonal frequency-division multiplexing (OFDM) is considered to be better techniques for multicarrier wireless communication. It has tolerance to inter-symbol interference and good spectral efficiency but are subjected to nonlinearities of power amplifiers, due to their high peak-to-average power ratio (PAPR). In this paper, some of the basic PAPR reduction techniques like: Peak clipping, random phase shifting, selected mapping (SLM) and dummy sequence insertion (DSI) methods have been discussed. The results obtained has been compared with original PAPR which suggests improvement in nonlinearity with modest reduction in efficiency and increase in hardware implementations. Among the various techniques SLM method gives low PAPR than other methods.