The Ofdm And Its Low Voltage Power Line In The Application Analysis And Simulation Study

With development of society the conflict between lack of bandwidth and the growing users gets worse. There are two important solutions to the trouble, one is to improve the efficient of bandwidth and the other one is to exploit new source for communication. Orthogonal Frequency Division Multiplexing (OFDM) is a digital modulation technique which has so many features such as high efficient of bandwidth, fast data transmitting. The communication on low voltage power line based on OFDM can use the existing low voltage power line network to communication which cost is low and is convenient. It is a new method of high speed communication and the research on OFDM and its application on low voltage power line has great significance.This paper makes a simple analysis on conventional digital modulation technique, and makes a complement analysis on OFDM. The paper analyzes the feature of power channel, and gives a detail discuss on the balance in time filed and frequency filed, and compares the two balance algorithms. Aim at the Peak-to-Average Power Radio (PAPR) , the paper gives detail analysis on its theory, the harm when PAPR is too high and the way to reduce PAPR. This paper purpose a improve algorithm on traditional PAPR, and gives out the result on MATLAB. The result shows the algorithm can be practical. As a application of OFDM, this paper purposed a solution which uses low voltage power line to access internet. The product the scheduled remands. The main content and creative work in this dissertation are as follows:(1) When the feature of power channel is bad ,and the Signal-Noise-Ratio(SNR) is slow,OFDM will cut off some subband so that the speed of the communication will slow. The paper place the balance technology into the OFDM system,then make some subband return to communicate,and this will get high speed communication.(2) One disadvantage of OFDM is its PAPR is too high,many indicates aim to slow down PAPR can not come to relativity because of their high calculate.This paper ameliorate some tradition algorithms. Both theoretics analyse and experiment indicate that the indicate ameliorated reduce the calculate.(3) As a application of OFDM, this paper purposed a solution which uses low voltage power line to access internet.Based on the solution,I accomplish the design, execution, debug and experiment of PLC MODEM.