Research On Coverage Problems Based On Wireless Sensor Network

WSN(wireless sensor networks) has synthesized sensor techniques, embedded computations, distributed information processing and wireless communication, can cooperate to complete the real-time monitoring, sensing, gathering of the objective information, then carries on processing to the gathering information and transmits it to the user. Generally, WSN is composed of massive sensor nodes deployed in the monitoring regions, sensor nodes are limited in battery power capacities and deployed in the nobody-defending environment, so they cannot be continually charged, simultaneously they need to frequently communicate with the base station, therefore the effective energy usage is the key problem which WSN needs to solve.As sensor nodes in WSN are usually distributed randomly and densely, this meight produce the coverage-overlap between sensing ranges of many sensor nodes, thus cause the appearrance of redundant sensor nodes. Massive redundant nodes will intensify message relevances between neighboring sensor nodes and communication conflicts with the base station, inevitably intensifies the energy consumption of the sensor node, this will pose the serious threat to the sensor node which has limited power capacity. In addition, in some specific applications (i.e. mobile target tracking), because of the factors that the mobile target itself, the physical properties of the sensor node and network obstacles, cause the sensor nodes which are farside from the target cannot sense the target or the error of the sensing datas is bigger, if these sensor nodes are in active, that will be of no value, moreover this will waste the energy of the sensor node.In order to solve the above problems, this paper conducted the thorough research to the coverage control problem in WSN, and proposed static and dynamic coverage control algorithms which can be fast, accurately examine the redundant sensor nodes in the network; And put them in the low energy-consumption (i.e. dormant) state, thus effectively reduced the energy consumption of the sensor node.First, based on the perimeter-coverage, this paper proposed one kind of effective, distributed redundant node search algorithm EDRNS, realizing the static coverage control of the entire network. Throgh transforming the two-dimensional space problem into the one-dimensional space problem, EDRNS can effectively simplify and reduce the complexity of the problem. The algorithm not only guaranteed the overall coverage of the monitoring region, but also examined the redundant nodes in the network very quickly.Then, on the foundation of further analyzing the characteristics of static coverage control algorithms in WSN, combining with the characteristics of WSN and sensor node themselves, this paper proposed one kind of dynamic coverage control algorithm ID-DCC(information driven dynamic coverage control) which was suitable for mobile target tracking applications. Namely through constructing effective management-regions nearby the mobile targets, only the sensor nodes in management-regions responsibly completed the requested task, the rest nodes outside the management-regions were put in dormant state; At the same time, the ID-DCC algorithm unified the EDRNS algorithm to further carry on the coverage-redundancy control to the management-regions, therefore effectively reduced the overall energy consumption of the network system.Finally, using the NS-2 simulation and ARM3000 embedded platform, this paper carried on the validity and simulation to the proposed algorithms. The results indicated that under the guarantee of the requested network coverage, the algorithms reduced the overall energy consumption of WSN effectively and lengthened the network lifetime.