Performance research of clipping LDPC-OFDM system based on MMSE iterative reception technology

One of the efficient ways to reduce the peak-to-average power ratio in multi-carrier system is clipping method, but it can cause the outspread of frequency spectrum, and then increase the nonlinear distortion and clipping noise. At the same time, it also can worsen the bit error ratio performance in multi-carrier system. In this paper, a nonlinear LDPC-OFDM system has been the research background for reducing the high clipping noise and distortion in clipping system. A novel algorithm named minimum mean square error (MMSE) iterative reception algorithm has been proposed in this paper, which is based on Ochiai clipping distortion mitigating algorithm and clipping distortion reconstructing iteration (CDRI) method. The MMSE iterative reception algorithm combined MMSE algorithm with iterative reception method to reduce clipping noise and distortion under various iteration times. At the same time, LLR-BP process has been intruded to decode LDPC and optimize BER performance. On the other hand, clipping process in LDPC-OFDM system has been mapped to a series of clipping index coding, and maximum likelihood (ML) decision algorithm has been used to recognize them.