Research On The Reliability Of Power Line Communication Network Based On Reconfigurable Algorithm And Code Distance Feedback

With the development of the broadband power line communication (PLC) access network, LAN and large scale monitoring and control network based on PLC, more and more reliability requirements, especially the connectivity of the network arises. The reliable data link is the key of the reliability problem in variable PLC channel. As previous documents and research achievements focus very little on the reliability of the PLC network, the main reasons that influence PLC network reliability is studied, and this work focus on the systematical methods and techniques that improve the reliability and effectivity of the PLC network theoretically and experimentally in practical engineering.Previous achievements including PLC channel input resistance, noise, reflection properties and channel model, are briefly discussed and summarized to extract the dynamic characters of the PLC channel. The existing achievements about the reliability of the PLC network are emphasized, present status of PLC research and applications are analyzed, and the most urgent problem, the reliability of PLC network is proposed for PLC network with a large scale of communication nodes.The OSI model and hierarchical classification method are applied in the research and the factor is pointed out that present PLC network is the lack of the interconnection function of Network Layer, which will affect the reliability of PLC network. It is very necessary to add Network Layer fuction in MAC layer, which could be accomplished with low cost and least hardware consumption. The reconfiguration property of PLC network is studied and the problem is pointed out that the reconfiguration in logic layer is the problem of initialization. The reconfiguration lemma is studied by step-by-step initialization strategy, and further the theorem is proposed and proved in x step strategy. Difference with common physical repeator network is distinguished and synchronization method is detailed. The reconfiguration algorithm is located at MAC layer with least physical layer affection, which is universally adaptive to most of the current PLC hardware platform.The topology after reconfiguration is studied further and a low cost TDMA- like protocol in MAC layer is also proposed for hybrid PLC network for the reliability of the data link, and M/D/1 model is utilized for the comparison with polling system and for the performance of the proposed protocol. The limitations in practical engineering to proposed algorithm are analized, and engineering algorithms that passed field test are given, as well as the general cycle time of the reconfigured PLC network that will be interested to remote supervisory applications.Aim to get universal adaptive to hardware platform as reconfiguration algorithm does, channel coding is utilized for error control to improve the communication reliability, and the basic principle of channel coding for the designing target of reliability is proposed. To increase signal-noise-ratio, the method that uses repeat-coding accumulator to construct channel coding is proposed. The soft accumulator can be realized in data link layer when no accumulators exist on physical layer.The channel coding bit accumulator is designed, majority judgment algorithm is proposed for error correction, and the performances of channel error rate with the majority judgment and accumulator together with the practical engineering field test results are detailed. The processor resource consumption for accumulator channel coding is studied comparing with classical TS-ARQ algorithm. This work points out that the channel coding with accumulator can reduce the processing resource consumption, and classical TS-ARQ algorithm is difficult to reach its theoretical performance due to the error rate of the preamble, and better performance of PLC network will be reached by channel coding with accumulator.The basic requirement of indirect channel evaluation is studied further, the method of utilizing channel code distance for discrete interval division of channel quality is proposed for channel coding reference, and the algorithm is given comparislly. The channel coding with feedback of channel quality can improve communication effectivity with satisfying the top aim of increasing reliability.Aim to interface PLC network with external network, this work proposed that embedded TCP/IP stack is suitable for the establishment of the gateway, and the reference model and basic structure of TCP/IP stack are addressed. The interface method with CGI is studied and discussed, and the details for the implementation of application layer are given.For the applications of reconfiguration algorithm and channel coding with accumulator, the spread spectrum based PLC module is designed with pointing out the limitation of PLC network applications. The research and development of narrow band PLC module is focused, designing strategies, the factors that affect physical layer performance and corresponding solutions are detailed. The networking methods and engineering example applied in lighting monitoring and control system based on narrow band PLC network is introduced.The proposed PLC network reconfigurable algorithm and channel coding based on accumulator with little limitation from physical layer, have excellent universal applicabilities. The design strategies of single-chip embedded PLC gateway and communication modules have important reference value for develop reliable PLC network components. The proposed reconfiguration algorithm, channel coding, networking strategy and designed PLC module, which are proofed by long-term engineering field test, can establish favorable foundation for the progress of PLC network with a large scale of nodes applied in more and more application fields.