Research On The Impulse Noise In The Power Line Communications Systems

Based on the nature of impulse noise in the lower voltage power line communications (LV PLC) channels, LV PLC channels are supposed to be memory channels, that is Markov nature. In the paper, the characteristics of LV PLC channels are analyzed in detail and a Markov model is proposed to model the channels.The increasing interest in modern multimedia applications, such as broadband Internet, HDTV, etc. requires new access techniques for connecting private premises to a communication backbone. One promising technology, broadband over power-lines (BPL), intends to use the existing power-line network as a high-speed digital data channel to connect the private users to one another and to a very high data rate backbone. Each home is equipped with electricity by means of low voltage (LV) power-line grid. LV lines are distributed to each power plug in every room in a house. Thus, LV power-lines can be an appropriate candidate for providing broadband access to all the users in a building and home networking. However, like other technologies BPL also faces its own set of obstacles and technical challenges.Then, the Baum_Welch algorithm for the Markov model is discussed, which is able to find effective solutions to the model parameter estimation as well as one of the basic methods to conduct training Markov model parameters. After a full study of the overflow problem, modified Baum_Welch algorithm is presented to avoid the overflow completely. The parameter estimation and simulation of Markov model is carried through with Baum_Welch algorithm.Finally, the error-free distribution of four typical modulation channel in two typical application environments is measured, as well as the characteristics of them are analyzed. This conclusion can verify that the proposed Markov model and the solution of the Markov parameters are correct and are available with the situation of PLC channels.