PAPR Reduction algorithm in conjunction with adaptive DPD in multicarrier transmission system

Abstract

Multicarrier communication and in particular Orthogonal Frequency Division Multiplexing (OFDM) is used as a main transport technology in many high bit rate wireless, mobile communication including broadband internet access system, as OFDM has high spectral newlineefficiency, easy implementation and can combat inter symbol interference and multipath fading under frequency selective fading channel. OFDM signal is generated using Inverse Fast Fourier Transform (IFFT) signal processing, which is equivalent to the summation of multiple subcarriers. Apart from having several advantages, OFDM system also has few demerits like, symbol timing offset, carrier frequency offset, inter-carrier interference and high Peak to Average Power Ratio (PAPR). Among these high PAPR is a major hindrance. The formation of quadrature time domain series as a weighted sum of sinusoids by IFFT is the major cause of newlinePAPR. Large PAPR which is not desirable in OFDM systems require linear power amplifier with large dynamic range to reduce PAPR leading to a more expensive implementation. newlineIntermodulation products like in-band and out of band distortions which are not desirable may arise by using a power amplifier which is not linear. Using a nonlinear power amplifier may result in intermodulation products like, in-band distortion and out of band distortions. These are undesirable phenomenon in communication system. As per literature survey, techniques have been developed in view of improvement of bit error rate and additional side information like, partial transmit sequence, selective mapping, clipping and filtering, companding, tone reservation, coding and also a few hybrid techniques. Every proposed method is evaluated with complementary cumulative distributive function of PAPR, which shows the period of time the level of the signal exceeds the average power level of the measured signal and bit error rate of the system. The simple clipping method shows the lowest PAPR but worst BER.