【作者】 邢萧飞；

【导师】 王国军； 李颉；

【作者基本信息】 中南大学 ， 计算机科学与技术， 2012， 博士

【摘要】 无线传感器网络是一种集信息感知、采集、处理和传输为一体的网络系统,它将逻辑上的信息世界和客观上的物理世界联系在一起,正深刻地改变着人与自然的交互方式,因而被广泛地应用于军事、工业、农业、医疗和抢险救灾等领域。覆盖控制是无线传感器网络所提供服务质量的基本问题之一,其目的是利用部署的传感器节点来感知目标区域或目标对象,并达到所获取信息的有效性和完整性。覆盖控制决定了传感器网络对物理世界的感知能力,是推动传感器网络从理论走向应用的必经之路。本文研究的目的是针对以随机方式部署的无线传感器网络设计具有节能特征的网络覆盖优化算法和协议。主要是从覆盖率控制模型、多属性目标覆盖、网络多重覆盖以及移动目标的动态覆盖等方面展开研究,遵循提高网络的能量利用效率的设计准则,以达到实现一个能量高效的网络覆盖控制优化方案目的。本文的主要工作包括以下四个方面：(1)针对随机分布的网络覆盖控制问题研究,提出了基于概率的网络覆盖控制模型PCCM。考虑到网络边界效应影响,模型首先计算传感器节点位于网络内部及其边界两种情况下覆盖面积的期望值,进而得到节点总覆盖面积的期望值；根据用户对覆盖率的要求,依据条件概率分布函数计算得到所需要部署节点的数量。模型反映了网络覆盖率与部署节点数量、节点感知半径与监测区域面积之间的函数关系。在此基础上,依据随机图理论推导得到网络连通性的概率模型。PCCM模型可以指导用户对网络覆盖率及连通率等网络属性的控制。(2)针对异构传感器网络的多属性目标覆盖研究,利用线性规划工具将其建模为最优值覆盖集求解问题,提出了一种基于分簇结构的目标覆盖算法CTCA。其核心思想是依据节点的剩余能量的多少及感应能力的高低,在每个簇结构内求解局部最优覆盖集,然后在此基础上得到接近于最优解的全局覆盖集,最后调度节点相应的感应模块去覆盖其感知范围内同属性的目标。实验结果表明所提出的算法能够有效提高网络节点的能量利用效率,延长网络生存期。(3)针对无线传感器网络多重覆盖算法研究,借助于勒洛三角形的几何特征提出判断区域覆盖度的定理,并以此为基础设计了一个基于勒洛三角形的多重覆盖算法RTC。算法的核心思想是利用节点局部位置信息,通过在节点感应圆周上构造勒洛三角形和所提出的覆盖定理来判断网络的覆盖度,并根据网络节点的剩余能量的高低进行节点状态调度。实验数据分析表明RTC算法在确保网络覆盖质量的条件下能够有效减少网络中冗余节点的数量,从而提高网络能量利用效率。(4)针对移动目标的实时监测协议研究,提出了一个自适应移动目标动态覆盖协议。协议的主要思想是首先对移动目标周围的节点,利用竞争机制构造出一个动态覆盖组对目标定位与实时监测；然后利用所提出的目标移动位置预测模型及节点状态调度策略来更新该动态覆盖组,这样可以有效提高节点对目标实时监测的时效性和能量利用效率。最后,借助于节点自适应数据报告频率自调整机制而实现降低网络节点之间通信量的目的。实验数据分析表明所提出的协议在网络能量利用效率、目标定位精度等方面具有很好的性能表现。综上所述,本文针对无线传感器网络的节点覆盖控制问题提出了相应的解决方案,对于推动无线传感器网络的研究和实用化具有一定的理论意义和应用价值。更多还原

【Abstract】 Wireless sensor network (WSN), as an integrated network which can perform information sensing, gathering, processing and delivering, can connect the logic information world with the real physical world. It has been greatly changing the way of interaction between human and nature. There are wide potential applications for WSNs, such as military affairs, industry, agriculture, healthcare, disaster succoring, etc. Coverage control is one of basic issue of quality of service (QoS) on WSNs. The goal of coverage control is to sense the monitoring area or targets by distributed sensors, so WSNs can collect valid and complete target information. Coverage control determines the monitoring performance on physical world for WSNs, so it is the indispensable road to accelerate the practicability of WSNs.This thesis is primarily to design optimal coverage algorithms and protocols with characteristic of energy saving for WSNs. Based on these several aspects--coverage ratio control model, polytype target coverage, multiple coverage degree, and dynamic coverage for mobile target, it follows the design criteria of reducing network consumption to achieve the purpose of an energy-efficient network coverage optimization scheme.The major work and innovative achievements of this thesis can be divided into the following four chapters:(1) Aimed at coverage ratio control of network, we propose a probability-based coverage control model (PCCM). Considering the border effect, PCCM firstly calculates the expected coverage area of sensors under the two cases:sensors located in the monitoring area, and sensors located near the border of monitoring area. Then, it gets the total expected coverage area of the deployed sensors. According to the requirements of users for coverage ratio, it gets the number of needed sensors to be deployed under the conditional probability distribution function. PCCM reflects the relationships between network coverage ratio and the number of deployed sensors, the sensing radius of sensor, the area of monitoring region. Based on the PCCM and the random graph theory, we also propose a network connectivity probability model. The proposed model can help users to control the network coverage and connectivity ratio in deploying sensors to the monitoring area.(2) Aimed at polytype target coverage for heterogeneous WSNs, we propose a cluster-based target coverage algorithm (CTCA), modeling polytype target coverage to optimal cover set problem based on linear programming. The key idea is to construct an optimal cover set in each cluster by the residual energy and coverage capability of sensors. Then, it achieves a suboptimal cover set for the whole network. Finally, CTCA schedules the corresponding sensing modules of sensor to cover the targets with same attribute. The simulation results show that the proposed algorithm can improve the energy efficiency and prolong the network lifetime.(3) Aimed at multiple degree coverage for WSNs, we propose a Reuleaux triangle-based к-coverage algorithm (RTC) on the basis of the coverage degree judgment theorem by using the geometrical characters of Reuleaux triangle. The key idea is that using the local position information of sensors to judge the coverage degree by constructing the Reuleaux triangle on the sensing circle of sensor. The algorithm schedules the suitable sensors into active status to cover target area. The simulation results show that the proposed algorithm can effectively decrease the number of sensors in the active status satisfied the coverage degree requirements, which improves the energy efficiency of network.(4) Aimed at real-time monitoring for mobile target, we propose an adaptive mobile target dynamic coverage protocol (AMTDCP). The main idea is that first the sensors near the target construct a dynamic coverage group (DCG) based on competition mechanism to locate and real-time monitor the target. Then, we use the proposed mobile target position prediction model and sensor status scheduling mechanism to update the DCG, which can improve the dynamic coverage quality and energy efficiency greatly. Finally, the communications volume of network is decreased by an adaptive data report frequency mechanism. The simulation results show that the proposed protocol has a better performance on the metrics of the total energy consumption of network, positioning accuracy, etc.In summary, this thesis focuses on coverage control problems and proposes its solutions. Our research has academic and practical value for advancing the theory and practicability in WSNs.更多还原