Research On Network And Channel Access Optimization Of Low-voltage Power Line Communication

There exist a large number of distributed power supplies and energy storage devices in the Energy Internet,which worsens the environment of low voltage power line communication(PLC).Therefore,it is of great significance to improve the network performance of low voltage PLC.At present,studies on low voltage PLC are mostly carried out on the basis of symmetric channels.But the truth is the low voltage PLC channel is asymmetrical in some cases.In view of this situation,taking the data link layer and network layer of the PLC protocol stack as the research object,the paper aims to improve the network performance in the asymmetric channel environment by analyzing the rapidity of low voltage PLC network,the robustness of network,the performance of network unicast and multicast routing communication,as well as the performance of overall network saturation:To solve the existing problems of relatively long network time caused by the delayed topology response to dynamic changes in the current network method,a network method based on CSMA/CA+TDMA hybrid protocol for low voltage PLC is proposed in the asymmetric channel environment.The network rapidity can be improved through the continuous interaction with the unknown environment for trial and error,the association with registered node information,as well as the periodical training for optimizing the shortest cluster tree rooted at the gateway.The multi-subnet rapid fusion method based on CSMA/CA+TDMA hybrid protocol can be discussed under the condition that the distance between nodes is relatively far or the channel environment is relatively harsh.The method can intelligently identify multiple networks in the area,select the network with the smallest media access control(MAC)address as the network fusion direction,dissolve the network with relatively big address,and solve the problem of network uncertainty fusion.After the network is dissolved,the station can be registered and networked through trial and error learning to ensure the integrity and rapidity of the network.Moreover,the validity and generalization ability of the method can be verified by simulation.To solve the existing problems of a negative impact on network robustness caused by the nodes' insertion and extraction after the completion of network,a low voltage PLC network maintenance and self-healing method based on small world model is proposed.With bandwidth adopted as the constraint and environment self-adaptation adopted as the learning goal,the network maintenance method based on small world model is used to dynamically perceive the network state information and continuously learn the occurrence rule of abnormal events.In the case of malfunction,self-adaptive selection of the recovery path will ensure the real-time transmission of data,thereby realizing the self-healing of network.With the adoption of small world network model,agents with stronger network connectivity capabilities can be intelligently selected by the sub-nodes,thereby improving the robustness of network.To solve the existing problems that genetic algorithm has poor local search ability under the constraint of Qo S parameters and it is difficult to obtain the optimal solution of on-demand routing on condition that network robustness should be ensured,a routing method based on improved genetic ant colony algorithm is proposed in asymmetric channel environment.Since the source nodes and destination nodes are not involved in crossover and mutation,the generation of invalid chromosomes can be effectively avoided.The optimal retention mechanism is first used to find an approximate optimal solution,and then the approximate optimal solution is converted into the initial pheromone of ant colony algorithm to find the global optimal solution.The unicast and multicast communication of nodes can be realized by the improved algorithm.The effectiveness of the improved algorithm compared with the original algorithm will also be verified by simulation.To solve the serious impact on the overall saturation bandwidth utilization and access delay caused by channel asymmetry and noise interference,an improved adaptive p-persistent CSMA game optimization method for low voltage PLC station numbers limitation is proposed.With the adoption of the hidden Markov model,the current state of the game(e.g.number of competing nodes)can be estimated by nodes.Then each node adaptively changes its nash equilibrium strategy based on the estimation of the active nodes,by controlling packets sent by nodes and reducing collision probability to data packets,so as to optimize the power line channel transmission status and improve the network saturation performance.