The Algorithm Of OFDM Technology In Medium Voltage Power Line Communication

Based on the channel characteristics of the medium voltage power line, this work applies the technology of OFDM(Orthogonal Frequency Division Multiplexing) to construct a system of medium-voltage power line carrier communication. At first, this paper presents the background and significance of the medium voltage power line communication as well as the key point and the challenge of the technology.Considering the existent structure of the power network in conjunction with the literacy investigation and achievement of the research, the paper summarizes the channel characteristics of the medium voltage power line, including characteristics on impedance, decaying and noise. At the same time, the basic theory, system constitute, drawback and gain of OFDM technology are analyzed in this paper, together with some correlative technology.In order to satisfy the need of the data operation and take the characteristic of medium-voltage power line environment in to consideration, we explore how to solve the problem of system synchronization. In this work, the key to the solution is to adopt a data assistant method based on the training sequence. Herewith, we firstly build up the pilot structure in frame, based on which some sound methods such as coarse timing synchronization, fine symbol timing synchronization, coarse and fine symbol synchronization of the frequency are proposed in the next step.OFDM communication system is designed experimentally according to the design index which is applied in the power line system. The paper also presents the algorithm of some key modules. For the dispatching end, the kernel module consists of channel coding, digital modulator, matrix transform, and digital frequency conversion. For the receiving end, the module is composed of digital down conversion, synchronization control and channel decoding. Finally, as a practical result we show the feasibility of this system based on the simulation in MATLAB environment and display the analysis on spectrum along with the situation of miscoding rate .