Research Of PAPR Reduction In OFDM System Based On PTS Algorithm

Orthogonal Frequency Division Multiplexing (OFDM) is the technique that divides the high rate data into many low rate data which can be transmitted onto some orthogonal subcarriers. OFDM can be used in counterworking with frequency-selected fading. Besides OFDM has many advantages, such as high spectrum efficiency, easier modulation and demodulation and a receiver without complex equalizer. However,OFDM has some drawbacks, one notable problem is the high Peak-to-Average-Power Ratio (PAPR).This dissertation focuses on reducing the PAPR problem.It has important theoretical meaning.From the implement angle, the advantages and disadvantages of signal pre-distortion technology, coding technology and probability technology are compared in this dissertation. PTS algorithm in probability techniques is mainly researched. The factors which influedce the performance of PTS are discussed. The improved PTS schemes based on adjacent partition and The improved PTS schemes based on iterate method are proposed.A new systematic sub-block partition method is proposed in the improved PTS schemes which is based on adjacent partition.The basic algorithm of the new algorithm is generate a set of sequences that should not be similar to the high PAPR sequences.The new set of sequences are used to reduce the PAPR of OFDM signal. The superiority to PAPR reduction of the improved PTS schemes which is based on adjacent partition is validated by the simulation of Matlab software, more importantly, the computational complexity of new algorithm is less than conventional PTS algorithm,and in the implement aspect, the new algorithm is easier to implement than the pseudo-random method.The basic algorithm of the improved PTS schemes based on iterate method is that combining the PTS algorithm which uses iterate method and the amplitude clipping.The computational complexity of PTS algorithm is reduced, at one time, the capability of OFDM system to reduce the PAPR is enhanced.The enhanced capability of OFDM system is validated by the simulation of Matlab software.The combined algorithm is used in MIMO-OFDM system further. The channel capacity and transmission rate of wireless communication system are highly enhanced ,because of the combination of MIMO and OFDM. But the MIMO-OFDM system have the same drawback as the OFDM system,what is the high PAPR. The improved PAPR schemes is proposed by integrating the inherent characteristic of MIMO-OFDM system. The algorithm of the new scheme is combining the Concurrent PTS and the amplitude clipping. The enhanced capability of OFDM system is validated by the simulation of Matlab software.