OFDM系统峰均比抑制的迭代FFT算法

传统的选择映射算法（SLM）中，要得到比较好的峰均比改善效果，需要比较多的独立分组数，这样运算量就比较大；传统的部分传输序列法（PTS）中，如果要获得最佳的相位旋转因子，需要遍历所有的可选信号，这样的计算量随分割的子序列数按指数增长。在正交频分复用（OFDM）系统中，采用快速傅里叶变换（IFFT和FFT）来实现高效的调制和解调，本文针对OFDM的高峰均比（PAPR）问题，结合限幅法操作简单和选择映射算法（SLM）以及部分传输序列法（PTS）对信号无畸变和效率高的优点，提出了一种基于迭代FFT的峰均比抑制算法，该算法利用系统中已有的IFFT（FFT）调制模块来降低OFDM的PAPR。并通过仿真试验证实该方法可以显著降低OFDM信号的峰均比，具有一定的工程意义。

Reduction the PAPR of OFDM Systems Based on Iterative FFT Algorithm

In the traditional of selective mapping (SLM) algorithm, in order to get better PAPR reduction, more independent sequences are needed, so the computation is relatively large. In order to get optimum phase weighting factors, Partial transmit sequence method (PTS) requires the exhaustive search over all combinations of the allowed phase factors, and the search complexity increases exponentially with the number of sub-blocks. In the Orthogonal Frequency Division Multiplexing (OFDM) system, The FFT and IFFT are used to realize the high-efficiency modulation and demodulation. In this paper, in order to solve the PAPA problem of OFDM system, a new method for PAPR reduction was proposed which is called iterative FFT algorithm. The new method combined the simple of clipping and the distortionless and high-efficiency of SLM and PTS. Because the FFT and IFFT module has been used as modulation, so it without need add another module. Through the simulation it is found that the new method can reduce the PAPR of OFDM effectively, which have certain significance of engineering.