| Wireless sensor networks aim to collaboratively sense and monitor the outside world autonomously with a huge number of distributing sensor nodes as terminations,and to perform communication and information transmission in the manner of multihop,self-organized and collaborative,then to accomplish goals intelligently,integrating autonomous decision-making and self-control abilities.These sensor nodes have characteristics of small volume and low power consumption,as well some ability limitations of computation and communication.With these characteristics including high practicability,settings flexibility,network scalability and access variability,wireless sensor networks have attracted much more attention of academia and industry in recent 10 years,and has been widely applied in many fields such as smart cities,national defense and military,intelligent transportation,industrial and agricultural production,wisdom medical,environment and disaster warning,etc.As a new computing mode,wireless sensor network has become an interdisciplinary subject involving a variety of technologies and a key technology to construct intelligent Internet of Things system and to compute pervasively,playing a decisive role in the Internet of Things era.Sensor networks are usually deployed on a large scale no-man's land of high-risk,remote or hostile.Wireless sensor networks deployed in the ocean,shallow sea and lakes obviously have the characteristics including rapid attenuation of monitoring signals,strong noise interference,fast energy loss of nodes,high deployment cost and the varied proneness of sensor nodes' position or sensing direction as results of swing or drift.Therefore,in order to improve the monitoring ability of sensor node and the comprehensive performance of wireless sensor network,it's vital to establish an optimized node deployment strategy,which has become a basic and key issue of the related research on wireless sensor network,especially in the complex and changeable underwater application environment.Focusing on the issues of optimized deployment strategy on two-dimensional directional wireless sensor network,three-dimensional heterogeneous underwater sensor network and three-dimensional underwater network with heterogeneous sensors.The environmental characteristics and specific application requirements of network deployment in different target application scenarios are systematically studied in this thesis,then targeted and efficient optimization schemes on node deployment for wireless sensor network are explored to disperse node power consumption effectively,improve perceptual quality and extend network life cycle.The main works and research contributions of this paper are as the follows:1.An optimal deployment scheme on two-dimensional directional wireless sensor network.Aiming at the uneven distribution problem on directional nodes deployed randomly in two-dimensional wireless sensor networks for plane monitoring,an optimal sensing strategy under polar coordinates is proposed to guide the direction adjustment and sensing optimization of two-dimensional directional sensor nodes,so as to improve the sensing ability of network nodes through analysis of the characteristics of directional sensor nodes,probabilistic sensing model and the cooperative sensing model of multiple sensor nodes for monitoring target points.The experimental results confirm that the proposed algorithm can enhance coverage rate of monitoring area and the quality of sense service,and reduce the overall energy consumption of the network by using the distributing node synchronous scheduling mechanism,thus extend the network life cycle with continuous good monitoring ability,with the restrictions on total number of directional nodes in wireless sensor network.2.An optimal deployment strategy on three-dimensional heterogeneous underwater wireless sensor network.In view of the varied proneness of sensor node parameters including location,sensing direction and energy residual in three-dimensional underwater wireless sensor network on account of the complication of the underwater environment,sufficient research is surveyed on the correlations between the characteristics of the emergence and variation of monitoring targets and the external regularity,and the features of heterogeneous underwater environment within network monitoring,especially for the peculiarities involved clustering region,clustering degree and distribution characteristics of obstacles and target objects within each partition are analyzed,as well.The task of multi-sensor collaborative sensing and trusted multi-source sensing data fusion is achieved by means of discovering and extracting rules and correlation information from each influence factor as priori knowledge to assist evidence reasoning.The contrast experiment results show that the deployment strategy proposed in this paper can adjust and optimize the location distribution of wireless sensor nodes according to the requirements and characteristics of the monitoring regions,meet the sensing requirements of different regions,improve energy efficiency of network and nodes,and ensure the reliability of underwater sensing and monitoring quality.3.An optimal deployment scheme on heterogeneous nodes of three-dimensional underwater wireless sensor network.In view of the application of underwater heterogeneous sensor network for target surveillance and interception problem,in the application scenarios of simultaneous monitoring multi-feature data existing in the specified water area,the deployment strategy on heterogeneous node in wireless sensor network need to implement comprehensive considerations on various factors including network deployment cost,the network coverage performance and network monitoring lifetime and so on,to pursue an equilibrium solution to a variety of indicators and performance requirements.In this paper,we study and compare the differences of various heterogeneous sensors in the aspects of sensing ability,sensing model,communication ability and so on.In the constraint on node scale,a deployment and sensing optimization strategy on dynamic heterogeneous node is proposed,taking advantage of multiple 2-D vertical section monitoring,meanwhile,the task of collaborative sensing data fusion and coverage hole recovering is achieved,referring to compound sensing module.The experimental results show that the proposed algorithm can not only enhance the effective coverage rate of the network and node energy efficiency,but also balance the network load,so as to improve the comprehensive monitoring performance of the underwater heterogeneous wireless sensor network. |
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