Researches On Key Issues And Applications Of PLC Computer Network

Carrier communication over high voltage power line has been developing for near one hundred years. It has many applications for voice communication in power distribution, data collection from tele-control instrumentation, and so on. However, using power line within one transformer area to provide Internet access is a just recent development. Power Line Communications Networks (here after, "PLC Networks") addressed in this dissertation include technologies that use the low voltage power lines to carry data transmissions or establish a computer network. PLC Networks, due to the ubiquitous nature of Power lines, present a solution to providing wide reaching Internet access, which have important technological and economic implications. For this reason, power line communications have received international attention. A great many difficult problems have been overcome and the results are full of promise. As a developing country, China will have to lay out a large investment to catch up with other developed nations' information infrastructure. PLC Networks present an economical alternative to approaches currently used by other nations. The purpose of this dissertation is to develop PLC Networks suitable for the Chinese power system.As Internet gateways, PLC Networks must have functions consistent with TCP/IP protocol family. However, as IP protocol is the standard to hide low layer physical networks and to realize interconnection among various networks, the research emphases of a PLC Network must be to provide the physical layer suitable for power line and the data link layer which supports the IP protocols. The functions of layers in or above the IP protocol layer can be obtained directly from a general operating system. On the other hand, because the physical layer and MAC sub-layer are directly affected by the transmission nature of the communication media, and there are much interferences on the communication media, the peculiarities of interferences, models, and measures for suppressing the interferences represent the key issues facing PLC Network research. Several of these key issues have been studied in this dissertation. The author's main contributions presented in this dissertation include:Presentation of a model for the optimal frame length in a PLC Network. The length of the MAC layer frame in general-media computer networks is related to the method used in media access control. For a PLC network, the length of the MAC layer frame is associated not only with the method used in media access control but also with the nature of the interferences, since it suffers from a variety of interferenceswhich are non-periodic and asynchronous. At present, the main approaches to determine a frame length are borrowed from general-media computer networks, and thus no attention has been paid to the effect of the interferences. This dissertation discuss the nature of the impulsive interferences on the power line channels, and presents a model for finding a frame length and a simulated example using probability. By theoretical computation and simulation, it is shown that the optimum frame length in a given channel condition is easily obtained by the method proposed in this dissertation.Presenting a draw of the MAC protocol suitable for PLC Network. The research on carrier spectrum, modulation schemes and signal codes of PLC Networks has received much attention, while the MAC protocol of PLC Networks is usually adopted from general-media computer networks. In China, researchers in PLC Networks focus on the physical layer and implement solutions using oversea PLC chipsets and components. Up to now, no papers about MAC layer of PLC Networks have been published in China. This dissertation gives an outline of the MAC layer of PLC Networks which is suitable for the channel characteristics and modulation system, paying more attention to the peculiarity of channels modulated in OFDM and taking advantages of wireless networks and HFC networks. Therefore, there are less competition for channels and robust master-slave str...