A Modified FFT Algorithm using Pruning Technology Based on OFDM Wireless Communication System

Fast Fourier transforms (FFT) and Inverse Fast Fourier Transform (IFFT) processing is one of the key procedures in popular orthogonal frequency division multiplexing (OFDM) communication systems. This paper presents the study of an efficiency of the fast Fourier transform may be increased by removing operations of input values which are zero, and of output values which are not required; this procedure is known as FFT pruning. FFT pruning algorithm is utilized in NC-OFDM systems to simplify the FFT algorithm complexity in presence of subcarrier sparseness algorithm. The standard FFT algorithms assume that the length of the input and output sequences are equal. In practice, this is not always an accurate assumption, and this paper discusses ways of efficiently computing the DFT, when the number of input and output data points differs. Keywords-Cognitive radio, OFDM, FFT, Pruning