Reserch On The Adaptive Mechnism Of Energy Consumption In Wireless Sensor Network

With more and more applications of wireless sensor networks (WSN) widelyapplied, the research on this technology has attracted a lot of attention. Influenced byits own characteristics and working environment, the energy of the nodes in thenetwork cannot be replaced or supplemented. But energy is the basic condition for thenormal work of the wireless sensor network. Therefore, study on the energy savingtechnology has important significance for the development of wireless sensor network.The largest energy consumption module of the sensor node is wireless communicationmodule and the module is controlled by MAC layer directly. So the design of a goodMAC protocol is of great help to reduce the network energy consumption. In addition,the energy efficiency of wireless sensor network also has close relationship with thebalance of network flow. But the unbalanced problem of the flow in time and in spacealways exists. Therefore, a good MAC protocol also must be able to adapt to theimbalance of network traffic.The main work of this thesis is to improve and optimize the energy-savingmechanism of S-MAC protocol and design the traffic adaptive DC-SMAC protocol.This protocol effectively improved the energy utilization of nodes and prolonged thenetwork lifetime. First, we analyzed the existing problems of energy savingmechanism of S-MAC protocol，that S-MAC protocol can not change the duty cyclealong with network traffic. So this kind of circumstance will appear: The node has tosleep, but still there is data to send; the node is still in the idle listening state whenthere is no task in the network, wasting a lot of unnecessary energy. Second, thisthesis presented a dynamic duty-cycle mechanism for energy-saving based on thetheory of S-MAC protocol, this mechanism predicting the current node flowaccording to the packet number in the node queue. The duty cycle is increased to twotimes of the original when the network flow is large, and the duty cycle is reduced tohalf of the original when the network traffic is small. This mechanism avoided theenergy consumption of idle listening. This thesis also put forward a priority algorithmabout channel allocation combining traffic prediction mechanism, and it gave thepriority computation function. The node will calculate the current back-off valueaccording to the flow before sending data and the node with minimum value will havethe priority to access channel. This avoided collision energy consumption caused by the channel competition. Finally, this thesis compared the traffic adaptive DC-SMACprotocol and S-MAC protocol through NS simulation. The simulation results showthat the proposed adaptive duty cycle mechanism of DC-SMAC protocol caneffectively reduce the network delay, increase the network throughput, improveenergy efficiency of the node, and effectively enhance the network performance in thecoordination with contention window adjustment mechanism.