Study On Technology Of PAPR Reduction In OFDM System

With the rapid development of mobile communication technology, high-speed wideband mobile communication has been the developing trend of the global mobile communication. Precious resources of frequency should be effectively used, so as to meet the business demand of the high-speed and big capacity, and overcome the difficulties of the multipath fading when high-speed data is transmitted under the wireless channel. OFDM technology is proposed for sloving this problem, but a big problem of OFDM is the high PAPR. Thus the research on the PAPR problem is quite meaningful.The existing technology on PAPR reduction for OFDM can be divided into three classes, namely signal distortion techmques, probability techniques and coding techniques. The thesis studies on the representative methods of signal distortion techniques and probability techniques.For signal distortion techniques, this thesis analyzes two performance measures of clipping technique: the ability of the PAPR reduction and signal to effective clipping noise ratio (SCNR). An improved clipping algorithm is also analyzed, and the simulation result shows that it has better PAPR performance than traditional clipping algorithm. At last, the best ranges for the setted value of CR and RT in the clipping algorithm are proposed.For probability techniques, this thesis compares SLM (selective mapping) with PTS (partial transmit sequence) by simulation. This comparison provides proofs for the performance of the two algorithms.The thesis also proposes two improved schemes based on PTS. The first scheme makes ues of the unite division plus iterative method to improve the PTS. A detailed description for the process from the classical PTS method to the improved method is given in the first scheme, and the result is also simulated by matlab. The second scheme makes use of the connection method to improve PTS. Two different orders of connection are compared, and then the result of the best connection order is obtained. Finally, the performance of the second scheme is simulated.