基于正交频分复用的低压电力线载波通信技术

 电力线信道的复杂性使得其通信质量难以提高，正交频分复用（OFDM）技术可提高抗多径干扰能力，使电力线通信质量有望得到提高。本文分析了电力线信道的基本特性，建立了一个反映信道特征的近似模型，在已有的研究基础上提出了一种改进的子信道利用方法来实现OFDM技术在电力线载波通信中的应用；通过建立Matlab仿真模型，实现了基于改进方法的电力线载波通信仿真；结果表明，在电力线信道条件比较恶劣、数据传输误码率较高的情况下，依据改进方法传输数据较为可靠。

Communication Technology of Low Voltage Power Line Carrier Based on OFDM

The complexity of power line channel makes the task of improving communication quality difficult. Orthogonal Frequency Division Multiplexing (OFDM) could make a full use of frequency bandwidth and improve the capability of anti-multi-path fading and it can be implemented by Discrete Fourier Transform (DFT) by using DSP in practice. So the quality of power line communication could be improved. Characteristics of power line channel such as impedance, fading and disturbance are analyzed. These characteristics are related with considerable time-variant and frequency attenuation of signals. A simple model of low voltage power line channel is established in this paper to reflect the characteristics of power line channel approximately. An improved method is proposed in order to apply OFDM to power line carrier communication, with N subcarriers in each OFDM symbol to transfer N same codes. Theoretically, in the receiver, N codes demodulated from each OFDM symbol are the same but the error code could be induced by various disturbances. So a special operation is used in the receiver for finding the right code. The reliability of the communication is increased by sacrificing the speed, as has been simulated by establishing a Matlab model. It is indicated by the simulation result that reliable data transfers can be achieved for a bad power line channel with high error code rate. The problem of this method while being implemented on a project will be discussed in future.