The Research Of Power Line Carrier Communication Technology Based On OFDM

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.