【作者】 成战刚；

【导师】 高丙坤；

【作者基本信息】 大庆石油学院 ， 通信与信息系统， 2009， 硕士

【摘要】 电力线通信(Power Line Communication,PLC)是继电信、电话、无线通讯、卫星通讯之后的又一通信网,利用电力线实现数据通信有着很大的经济效益和应用前景。由于低压电力线网络的干扰问题是制约低压电力线载波通信发展和普及的主要障碍,而正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)调制技术具有频带利用率高、传输速度快、抗干扰能力强等优点,能有效提高频带利用率,缓解频带短缺矛盾。因此,对OFDM及其在低压电力线通信中的应用进行深入研究具有非常重要的现实意义。本文首先讨论了电力线载波通信的发展概况及应用前景,深刻解析了低压电力线的信道特性,包括时变特性、衰减特性、噪声干扰特性、相移特性及多径传输特性等,研究了影响电力线信道特性的各种因素,给出低压电力线系统通信信道模型,并对其进行合理的简化,增加它的实用性。接着论述了正交频分复用技术的基本原理、实现方法,总结出将正交频分复用技术应用于低压电力线载波通信系统中的优势所在及存在缺点,详细阐述了当前OFDM实现过程中的关键技术,如保护间隔、同步技术、信道编码与交织技术、信道估计及功率峰均值比(Peak to Average Ratio, PAPR)抑制问题等。给出了OFDM信号PAPR的定义,分析了OFDM中PAPR过大的原因及影响,推导出PAPR分布函数并对其进行仿真,归纳了OFDM系统中抑制功率峰均值比的算法,对其进行总结划分归类,包括有编码方法、信号畸变技术和相位旋转法,并对已有方法进行了评价和比较。最后本文针对输入序列定标方法存在计算量大的问题,提出了一种基于输入序列定标的降低OFDM功率峰均值比的简化方法,这种简化方法通过施加终止门限采用迭代计算实现。通过对改进后方法的仿真验证,改进的方法能大大降低计算复杂度。更多还原

【Abstract】 Power Line Communication is another communication network following telecommunications, telephone, wireless communications and satellite communications. Using of power line to realize data communication has great economic benefits and application prospects. Because of the interference problem of low-voltage power line network is the main obstacles to constraint development and popularization of low-voltage power line carrier communication, and orthogonal frequency division multiplexing modulation technique with advantages of high efficiency on bandwidth, high speed on transmission and strong ability of anti-interference, it can improve bandwidth efficiency effectively and ease the contradictions on shortage of band. Therefore, OFDM and its application in low-voltage power line communication are studied in depth has very important practical significance.This paper firstly introduces the development and application prospects of Power Line Carrier Communication, deeply analyzes the channel characteristics of low-voltage power line, including time-varying characteristics, attenuation characteristics, noise characteristics, phase-shifting properties and multi-path transmission characteristics, researches various factors of effects on channel characteristics of power line, in this paper the communication channel model of low-voltage power line system is showed, and it is made to be reasonably simplified and became more practicable. This paper elaborates on the basic principles and implementation methods of the orthogonal frequency division multiplexing, and summarizes the advantages and disadvantages for the orthogonal frequency division multiplexing which is used in low-voltage power line carrier communication system , and expatiates on the key technique of the current OFDM in practising , such as guard space, synchronization techniques, channel coding and intertwined technical, channel estimation and power average of peak rate(PAPR) inhibition problem and so on. . In this paper the definition of OFDM signal PAPR is given ,the causes and effects of making PAPR too large in the OFDM are analyzed, and there are PAPR distribution function formula derivation and emulation. This paper induces the algorithms of suppressing the ratio of the power crest value in OFDM system and makes a summary ,a classification and categorizes them. including the encoding method, signal distortion and phase rotation technique. Existing methods have been evaluated and compared in the paper. Finally aiming at the problem of inputing sequence calibration too complex , this paper proposes a simplified method based on the input sequence calibration to reduce PAPR of OFDM signal, the simplified method adopts iterative calculation through the termination threshold, through the simulation of improved method, the improved method can greatly reduce the computational complexity.更多还原