Measurements and Channel Characteristics of LV Power Line Communications Networks in China

Due to the fact that power lines are not designed for data transmission, power distribution grids are hostile to transfer high frequency communications signals, which lead to the fact that channel characteristics of power lines are very important for communications systems design. In this paper, the measurements of channel properties of power line communications networks in China are presented and discussed. Topology of the typical LV supply grid in China is introduced firstly, and the following part discusses the measurement methods in detail. According to the nature of distribution networks configuration, office blocks and residential buildings are tested respectively, and the methods of channel measurements are also introduced in detail. The measurements show that the main reason influencing the reliable communication of high-speed data on power lines is the attenuation characteristics of the high-frequency signal, which can be seen more obviously in the branches of power lines. For the multi-layer buildings, it is almost impossible to use the frequency range from 2 MHz to 20 MHz to realize the reliable communication from distribution transformers to each user, which must be solved with the aid of means, such as the repeater. As far as the signal´s attenuation, the lower frequency range is more suitable for the high-speed data communication on power lines. From the systems´ view of point, the frequency range of 2 MHz-10 MHz is more suitable for the power line networks to be used as the high-speed data access systems