The Research Of Channel Properties Of Low-voltage Power Line Channels

Access network of communication, being used for interconnection between user terminal equipment and the backbone network, is the bridge between the user and all kinds of Internet business. However, access network as the foundation of the important network resources, the cost of implementation, installation and maintenance is very expensive, which can usually be accounted for more than half of the total amount of network construction. Network operators have been thinking about how to solve the contradiction between Quality-of-Service of network communication and reduction of the construction cost of access network. Getting a balance of both sides can not only improve the competitiveness of Internet service providers but also enable the users to enjoy communication service with high quality and low price. Therefore, to explore a new access network technology has become a general research direction drawing great efforts.Power line communication(PLC) is a kind of highly effective method for signal transmission by using common power lines as a communication medium. PLC technology can make full use of the existing most extensive laid power wiring network resources. As the basis of undertaking power transmission functions, it can also support high speed data signal transmission, like the voice and video, the multimedia integrated service which has the incomparable advantage over other existing access network technology, such as the short time period of construction, low investment cost, without repeated indoor wiring and construction efficiency, etc. In this paper, firstly the necessity and meaning of power line communication under the background of Internet of Things are discussed, meanwhile the current development situation of power line communication for domestic and foreign research are introduced. In the following part, the differences of power line engineering environment between domestic and abroad are analyzed, whereby we make the conclusion that the existing channel model is not suitable for the domestic engineering environment. Then we focus on the analysis of low voltage power line channel transmission characteristics, including fading and noise characteristics and impedance characteristics. In order to find out the channel model parameters suitable for the domestic engineering environment, experimental tests are made for the indoor commonly used cross-sectional area of 2.5 was hard wire within 1 to 30 MHz bandwidth channel characteristic. Including: with fixed frequency f, the impact on the channel characteristic due to the change of wire length l; with fixed length l, the effect on the channel characteristic through adjusting the frequency f. Besides, influences of channel characteristic by the PVC material, lead space and lead height from the ground are observed from experimental tests. According to the measured data, the channel model parameters suitable for our country environment are calculated, and then with these parameters simulations of the channel model are implemented. The simulation results show good agreement with the measurement.