Research And Improvement Of Node Scheduling Algorithm For Wireless Sensor Network

Wireless sensor network(WSN)is a sensor network consisting of a large number of sensor nodes deployed in the monitoring area in manner of self-organization and multi-hop,with large-scale,low power consumption,low cost and self-organization and other typical features,it can be widely used inenvironmental monitoringand many other fields.The sensor nodes are usually powered by battery,and usually deployed in dangerous and complex areas where people are difficult to reach,so the wireless sensor network also has the high resource limited,difficult to supply features.Since the deployment of nodes is usually high density,this kind of deployment will cause communication interference,data conflict and other issues among the nodes,waste a lot of energy of nodes.Therefore,saving energy,extending the network survival time without affecting the quality of network services has become the focus of wireless sensor network research,at present the most direct method is the node scheduling strategy,node scheduling can make the coverage redundant nodes into the sleep state in turn,this can reduce the node energy consumption effectively and extend the network survival time.But in the existing node scheduling algorithms,the node sleep time is fixed,this cause some nodes have less chances to sleep,energy consumption too fast,node failure prematurity,network energy consumption is not balanced,at the same time,in the existing node scheduling algorithms,after the failure of the node they did not take any remedial measures,coverage holes appear in the network,reduce the quality of network service.In view of the above problems,combined with the existing node scheduling algorithms,this paper carries out the following studies:(1)Aiming at the problem of node sleep time is fixed in existing scheduling algorithm,the sleep time dynamically adjustment energy saving algorithm is proposedIn this paper,the proposed algorithm uses the surplus energy of the node as the discriminant mechanism to dynamically adjust the node sleep time,which is different from the sleep time is fixed in the existing scheduling algorithm.When the node surplus energy is higher than the energy threshold,the node has more energy left,shorten sleep time,the node wakes up in time,complete the sending,receiving and transmit data tasks,give other nodes more sleep opportunities;when the node surplus energy is lower than the energy threshold,the node has less energy left,extend sleep time,reduce the node energy consumption,extend the node survival time.Simulation results show,this algorithm relieves the occurrence of premature failure of the node,and make the network energy consumption balanced,effectively extend the network survival time(2)Aiming at the problem of network coverage reduced due to the depletion of node energyin existing scheduling algorithm,the looking for backup node coverage guaranteed scheduling algorithmis proposedIn this paper,the proposed algorithm selects backup node for the failure node,and work instead of the failure node,delay the network coverage decline,which is different from the existing scheduling algorithm does not consider the node energy depletion lead to the problem of network coverage decline.In the proposed algorithm,first assume that the node can be passive wake up,can receive the messages send by the neighbor nodes,and reply messages to the neighbor nodes,when the node surplus energy is lower than the energy threshold,the node is about to fail,and find backup node in its neighbor nodes which is in the sleep state,has more surplus energy and short distance to the node,then notifies the backup node to into the active state,working for the fail node.Simulation results show,this algorithm reduces coverage holes,ensures the quality of network services,extends the effective survival time of the network.