The Study Of Energy-Saving Mechanism Of MAC Layer And Clustering Mechanism Of WSN For Smart Grid

The smart grid is a fully automated power network to monitor each node (power user included) in the power network for its strong and self-healing character. There appears great economic and societal significance in the contruction of smart grid, which will promote the development of the Intelligent Community and Smart City, and change the user role in using electricity, and provide the power user with safe, fast, and economic electricity services, and reduce the emission of pollution and greenhouse gas.The WLAN technology based on IEEE802.11 is an important part of the smart grid communication technology, providing users with the the electricity network access services safely anytime and anywhere. Because most of the WLAN technology based terminal equipment use the battery power with limited cost and energy capacity, and in order to make the user terminal device used for a longer time in the case of not charging, there must be an effective mechanism of WLAN energy saving.Because of the shortcomings, for instance excessive Scheduling overhead and Insufficient energy-saving performance when used on large-scale scheduling of smart grid nodes,The existing 802.11 standard energy-saving mechanisms, such as PSM(Power Save Mechanism), APSD(Automatic Power Saving Delivery)and PSMP(Power Save Muti-Poll), are not appropriate.The paper proposed an improved PSCP scheduling mechanism based on PSMP,which define a new scheduling frame SPFand a dynamic AID adjustment strategy. The scheduling frame SPF is consist of SIM field and Control field. The Bitmap in the SIM field embedded by AP indicates the scheduling information of STA, and the control field represents the scheduling information. After receiving SPF frame, STA can determines whether it is in this scheduling period and conculates its sleep time by parsing SIM domain.In the SPF schedule, the Downlink data and Uplink data will be transmitted in one SU to advoid the calling up of STA again, which can make the STA keep sleeping as long time as possible. In addition, the PSCP mechanism can utilize the dynamic AID adjustment to further compress the SIM field in some special condition. In a word, the proposed PSCP can reduce the scheduling overhead of AP greatly and make the energy-saving maximize.In the same time, the paper propose a kind of WSN clustering mechanism that can be applied to the smart grid. The mechanism utilizes the score of the interaction between the nodes as the primary information of trust value evaluation, and then the node compute the direct trust value simply, and then send the trust value to Sink node to evaluate the final trust value. In next step, the Sink node sets up the black trust table to kick the node with too low trust value evaluation out of the network based on its trust value evaluation of nodes, and comprehensively considers the residual energy of nodes to find the best node with high trust value and abundant residual energy as the cluster head. The mechanism can reduce the cost of the network and the energy consumption greatly, and also ensure the safety of the network with the energy consumption balanced.