Research On Energy-saving Strategy Of Wireless Sensor Networks With A Mobile Agent Node

Wireless sensor networks are composed of a large number of Low-cost micro sensor nodes deployed in the monitoring area.The energy of nodes is limited,and because of its large number and complex deployment environment,it is often difficult to replace batteries or add electricity.So how to use energy efficiently to maximize the network life cycle has been an important research topic in this field.It is an effective method to eliminate "energy hole",balance the energy of the network and prolong the network life by introducing a mobile node to help the static wireless sensor network to collect data.Currently,researches on mobile node focus on mobile sink and mobile relay nodes,the network with a mobile sink needs to flooding the location information of the sink frequently,which will consume too much node energy and increase the overhead of topology construction because the network topology changes frequently.Mobile relay nodes are usually only suitable for Delay Tolerant Networks,and the networks can not respond to the monitoring data in real time.On the basis of maintaining the original data transmission route of the static network,this paper introduces the mobile node to collect the periodic monitoring data that does not need real-time response in the network.Information that requires immediate response from the system is transmitted to sink through the route constructed in the static network.In this way,the real-time response ability of the network is guaranteed,and the energy consumption caused by flooding of sink nodes is avoided.According to the topology classification of wireless sensor networks,this paper studies the motion methods and data collection methods of mobile nodes in planar network and hierarchical network.In a planar wireless sensor network,in order to balance data collection delay and energy consumption,the mobile node gathers data in the way of establishing the data collection tree by itself.When determining the direction of movement,the probability selection factor is added,so that the nodes far away from sink have higher probability to be accessed by the mobile node,so as to save the large amount of energy consumed by long-distance data transmission.The mobile node also dynamically adjusts the layer of the data collection tree and the moving distance according to the node density,so as to realize energy balance in different regions of the network.Finally,a location adjustment strategy is developed to solve the problem of the mobile node moving out of the network area.In hierarchical wireless sensor networks,the mobile node only need to access cluster heads,and they can collect the whole network data.In order to make the cluster data have longer local storage time before the arrival of the mobile node,THM algorithm is proposed.The algorithm merges the storage space of all nodes in each cluster into a virtual memory of large space.In order to achieve balance between saving network energy consumption and reducing data collection time,MWF algorithm is proposed,by adjusting the motion coefficient,the algorithm can make mobile nodes adapt to different network environments.By comparing with the algorithm in the static network and the similar algorithm with mobile nodes on the NS2 platform,it is proved that the algorithm proposed in this paper has obvious effect on prolonging the network life and balancing the energy consumption of the whole network.