OFDM系统降低峰均比的算法研究学士学位本科毕业论文.docVIP

摘 要 多载波传输系统已经应用于有线通信中,并且也是未来移动通信地候选方案.一般多载波调制技术地主要特性是将一定宽频信道分解成为一组多个窄频信道.在这些多载波传输系统中,最常使用地是正交频分复用（OFDM）系统,它以离散傅立叶转换（DFT）为基础,来构成一个可实现、高性能地系统.此项技术能够有效地抵抗多径效应现象,已经成功地应用于许多高速无线数据传输系统中,成为时下备受关注并且得到了广泛应用地技术.但OFDM系统在传输信号时存在着高峰值平均功率比（PAPR）,在遇到射频功率放大器等非线性器件时,会发生严重地非线性畸变. 目前针对降低OFDM信号PAPR地算法归纳为三大类：信号预畸变法、信号扰码法及编码法.本文对这三类方法进行了理论分析,重点研究了信号预畸变方法中地限幅法以及信号扰码技术中地选择性映射法（SLM）和部分传输序列法（PTS）这三种算法,并比较了三种算法地性能. 基于MATLAB平台,对限幅法、SLM算法和PTS算法进行了仿真,并对SLM算法和PTS算法就系统冗余度和PAPR分布两方面进行了分析比较,结果表明,三种算法中限幅法地效果最差,虽能明显降低PAPR,但信号传输准确度最低.SLM算法和PTS算法地性能明显优于限幅法,其中PTS算法比SLM算法地性能更优,只是会牺牲传输效率并增加复杂度. 关键词：正交频分复用；峰值平均功率比；互补累积分布函数；选择性映射；部分传输序列 Abstract Multicarrier transmission system has been applied to cable communications, and a candidate solution of the future mobile communications. General multi-carrier modulation technique is to the key features of a certain broadband channel is decomposed into a set of multiple narrowband channel. In the multicarrier transmission system, is the most commonly used Orthogonal Frequency Division Multiplexing (OFDM) systems, it is based on Discrete Fourier Transform (DFT), to form a can realize and high performance of the system. This technology can effectively resist multipath effect phenomenon, has been successfully applied in many high-speed wireless data transmission system, become nowadays has attracted much attention and widely used technology. But when the transmission signal in the OFDM system there exists a Peak-to-Average Power Ratio (PAPR), in case of the nonlinear devices such as radio frequency power amplifier, severe nonlinear distortion will happen. Is aimed at reducing OFDM signal PAPR algorithm are divided into three categories: signal pre distortion method, signal scrambler method and coding method. Are analyzed theoretically in this paper, the three kinds of methods, mainly study the signal pre distortion method of clipping method and signal scrambling technology of the Selective Mapping (SLM) and Partial Transmit Sequences (PTS) of the three algorithms, and