The Study On Dynamic Coverage Algorithm For Wireless Sensor Networks

Wireless sensor network (WSN) is a distributed network system composed of a large amount of micro-sensors, which are distributed in the area to be monitored and organized by themselves. It is generally used in the area or environment--where human being cannot or would not get in--to monitor the environmental parameters of interest. WSN transmits data collected by sensors to remote observers. Then observers can analyze the data to get a view of the environment. WSN has a broad application prospect in the fields of scientific research, civilian affairs and military affairs and so on.The limited and irreplaceable energy of the WSN nodes makes efficiently using node's energy a great important goal of WSN research. In practice, in order to enhance the quality of wireless sensor networks'server and improve network reliability, sensor nodes are usually large-scale, high-density deployment within the target area, which led to a large number of nodes'coverage area intersecting. This redundant coverage directly led to redundancy of data's collection and transmission, resulting in unnecessary energy consumption and shortening the networks'life time. Dynamic cover problem is in this case, by carefully scheduling the activities of the node, so that redundant nodes alternate work. We can use this kind of node deployment to extend the survival time of wireless sensor networks. How to using the inherent redundancy characteristics of the node deployment to extend survival time of the network is an important challenge during the design of wireless sensor networks, as well as an important content of the study.Based on The analysis of a large number of coverage problems, this paper proposes a coverage model MLVG based on local information and virtual grids, as well as the dynamic coverage algorithms based on MLVG, and achieve better results.In the model of MLVQ we divided the sensing area into regular virtual grids, and coded the grids, so that each grid correspondence with a unique digital code. Each node's coverage area can be denoted by a series of numbers. Finally we change the area coverage problem into a set coverage problem.The dynamic coverage algorithm based on MLVG is a distributed algorithm in the case of random deployment. This algorithm extends the networks'life time through alternating nodes'states of sleeping and activity. During the process of the algorithm, "lock" mechanism is used to avoid infinite iteration of distributed algorithms and deadlock phenomenon. We also considered the factor of nodes' residual energy to balance the energy consumption of the network. Finally, the algorithms simulation experiment results show that, in the case of ensuring the quality of coverage, our algorithm requires less sensor nodes to support the network and more sensor nodes live longer, and finally prolonged survival time of the network.