Clipping and Filtering Techniques for PAPR Reduction in OFDM Systems

This MATLAB code simulates the effects of clipping and filtering on PAPR reduction in OFDM-based wireless standards. The implementation also evaluates the BER versus SNR performance of original OFDM signals with PAPR reduction based on clipping and filtering schemes over AWGN channel. The code implements clipping as one of the simplest and most common PAPR reduction techniques by essentially truncating signal portions that exceed the predetermined threshold level. The clipping method introduces both in-band distortion and out-of-band radiation into OFDM signals, consequently degrading system performance including BER and spectral efficiency. The filtering operation, implemented through frequency-domain windowing or time-domain convolution, can reduce out-of-band radiation after clipping but cannot mitigate in-band distortion. However, the code demonstrates that clipping may cause some peak regeneration, where the clipped-and-filtered signal exceeds the clipping level at certain points. To reduce peak regeneration effects, the implementation includes iterative clipping and filtering operations through multiple loops to achieve desired PAPR levels, though this approach increases computational complexity. The algorithm structure incorporates threshold comparison for clipping, FFT/IFFT operations for filtering, and performance metrics calculation for PAPR and BER analysis. Key MATLAB functions used include fft, ifft for OFDM modulation/demodulation, and custom functions for clipping threshold application and filtering window design.