عباسعلی شریفی

The high peak-to-average power ratio (PAPR) is one of the main problems of an orthogonal frequency division multiplexing (OFDM) system. As a result of the high PAPR, the hardware complexity of the high power amplifier (HPA) is increased. Because, during the passing via a non-linear HPA, the OFDM signal is clipped. In the present study, we investigate the performance of complex Vandermonde matrix transform (CVMT) in a pre-coding based OFDM system to reduce the high PAPR. We show that the serial combination of two CVMT and inverse FFT (IFFT) matrices eliminates the impact of each other when their dimensions are the same. In this case, a sparse matrix is achieved by the multiplication of two CVMT and IFFT matrices. The obtained matrix has only one non-zero element in each row and column and hence the PAPR of the OFDM signals is remarkably reduced. The CVMT pre-coding approach is combined with a low complexity interleaving method to make a compromise between the PAPR reduction and implementation complexity. The valuable results are achieved for 16-QAM modulated symbols and compared with the conventional OFDM, Walsh-Hadamard matrix transform (WHMT), and discrete cosine matrix transform (DCMT) approaches.