Research On Key Technology Of Event Monitoring System In Wireless Sensor Network

Event monitoring is one of the most important issue of wireless sensor network, which is widely used in various monitoring based applications, such as toxic gas leak monitoring and fire detection monitoring. The recent advancement in wireless sensor networks provides a promissing technnique for the monitoring of toxic gas leak. This paper presents a framework for toxic gas diffusion event monitoring in wireless sensor networks and focus on sloving the error data filtering problem, data collection problem, diffusion source location problem and dangerous area detetion problem.Firstly, this paper aims at the problem of data processing in the monitoring system. Since sensor data usually accompanies randomness and there is larger difference in sensed data among different sensor nodes, which can not be characterized a uniform model to form a standard characteristic for the collected data by the sensor nodes. To solve this problem, this paper presents a temporal and spatial similarity based approach to detect error data in the network. Sensor nodes first determine whether the data is error using temporal similarity locally. If the sensed data is error, then it will be broadcasted to the cluster member nodes to further determine whether it is spatial error by using voting method. Cooperative decision among senosr nodes for error detection improves the accuracy for sampling sensor data.Secondly, this paper studies the problem of data filtering in the monitoring system. The sensor nodes that have spatial correlation are clustered as a group. Then the group can monitor and analyze the events collaboratively, which can efficiently reduce the wireless communication. This paper proposes a cluster based geographic routing method to send the collected data to the base station. Geographic routing data are helpful to locate the the position of diffusion event. Sensed data are sent to the cluster head by cluter member nodes.Then cluter head fuses the data and send the data to the base station by using geographic routing prototol, which can improve the speed of data retransmission and reduce the communication overhead.Finally, this paper focuses on the problem of localization in the monitorin system. When there is toxic gas diffusion happening, it is critical to locate and track the diffusion source.Earlier detection of the diffusion source can help people to save lives and properies. This paper presents a diffusion model based approach for the localizaiotn of toxic gas diffusion source. The least square method is used for the position estimation of the diffusion source,which can improve the efficiency of monitoring and decrease the overhead. In the system of toxic gas diffusion monitoring, it is necessary to mark the polluted area and triger the alarm information. This paper utilizes the solution of convex hull to calculate the area of toxic gas diffusion. It can simplify the detection approach and improve the computation efficiency and localization accuracy, which remind people keep away from the danger areas.