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1、太原理工大学 硕士学位论文 无线传感器网络中基于移动锚节点的定位算法研究 姓名：祁会波 申请学位级别：硕士 专业： 指导教师：冯秀芳 太原理工大学硕士研究生学位论文 I 无线传感器网络中基于移动锚节点的定位算法研究 摘 要 无线传感器网络(Wireless Sensor Network，WSN)集成了多种技术，它 是由部署在指定的监测区域内大量的低成本具有感知、协作、计算、可自 组织以及无线通信能力的微型传感器节点组成的网络。 WSN 应用范围很广阔，现已应用于军事、环境监测、复杂机械监控、 工业园区的安全监控等领域。而在这些应用当中，都需要目标定位技术的 支持， 获取节点的信息位置在 WSN
2、 的监测活动中是非常重要的， 可以说没 有位置信息的监测消息往往毫无意义；另外，节点定位也是目标跟踪、地 理路由等技术的前提。因此，对节点定位技术的研究是至关重要的。 在 WSN 的节点定位技术中， 根据在定位过程中是否测量实际节点间的 距离，可将现有的定位算法分为两类：基于距离的定位算法和距离无关的 定位算法。经过研究可知，前者定位精度相对较高，但硬件要求也高；而 后者硬件要求低，节点成本小，适用于大规模传感器网络，但是定位精度 却不高。因此，本文重点研究了无需测距的节点定位算法。 本文的主要工作归纳如下： （1）首先深入研究了 WSN 节点定位技术的基本原理，对目前常用的 节点定位算法进行
3、详细介绍、分类、分析和对比，总结各自的优缺点。 （2）重点研究了 APIT 定位算法，分析和总结了其存在的不足之处。 该算法是一种距离无关定位算法，在固定同构的密集网络中，可以得到比 较合理的定位精度。然而，在随机分布的网络中，定位误差较大，并且定 太原理工大学硕士研究生学位论文 II 位覆盖率较低。这是由于在随机分布的传感器网络中，其节点分布往往是 不均匀的，监测区域中有的地方分布的节点多，有的分布的少甚至没有， 从而造成比较多的节点位置不能被确定，其定位精度也受到严重影响。针 对以上问题，本文提出了一种基于移动锚节点的定位方法，其基本思想是， 在传感器网络中引入移动锚节点，在网络的初始化时
4、，通过一定的移动覆 盖算法尽量使锚节点能够分布均匀，从而改善未知节点的定位性能。 （3）通常，定位性能还会受到参与定位的锚节点数量的影响，适量的 锚节点有助于提高定位精度和定位覆盖率。为此，本文提出了一种基于异 构传感器网络的最佳节点数量的计算方法。从理论上可以预先求出指定的 区域中能够完全覆盖监测区域所需要的锚节点和未知节点的个数。 （4）对于 APIT 算法不能进行定位的无效节点（即只有 1 个或 2 个邻 居锚节点） ，本文给出了具体的定位方法。另外，还引入了 RSSI 量化模型 对 APIT 算法的定位精度进行修正， 升级第一阶段可进行定位的未知节点为 新的锚节点等方法。 （5）最后，
5、验证和讨论改进后定位算法的整体性能。采用 Matlab 7.0 仿真平台对改进后的定位算法与同类算法进行仿真对比。仿真实验表明， 采用本文提出的基于移动锚节点的定位方法，在定位的精度和定位覆盖率 等方面与同类方法相比有较大的改善。 关键词：无线传感器网络，节点定位，移动锚节点，APIT 算法 太原理工大学硕士研究生学位论文 III RESEARCH ON LOCALIZATION ALGORITHM BASED ON MOBILE ANCHOR NODE FOR WIRELESS SENSOR NETWORK ABSTRACT Wireless Sensor Network (WSN) inc
6、orporates multiple technologies. It is a network of numbers of low cost micro-sensor anchors disposed in a certain monitored area, with the ability to sense, coordinate, calculate, self-organize and communicate wirelessly. WSN can be widely applied in many areas, including military, the monitoring o
7、f environment, complicated machine and the safety of industrial park, etc. All these applications need the support of the technology of target localization. During the detecting of WSN, information of position which acquires nodes is great importance, and without location information, all the effort
8、s will become useless. Whats more, the localization of nodes is also the premise of some technologies, such as target tracking and geographical routing. Above all, it is absolutely vital to research the technology of nodes localization. And according to whether to measure the actual distance of the
9、nodes during the localization, the technique of nodes localization includes two kinds of localization algorithms: range-based localization algorithm and range-free localization algorithm. Some research indicate that the former one has a high 太原理工大学硕士研究生学位论文 IV precision and a high hardware requireme
10、nt, while the latter one has a low hardware requirement and a small cost for the nodes and it can be applied in large scaled network of sensors, but it is not very precise. So the range-free localization algorithm is studied in this thesis. Major tasks of the thesis are as follows: (1) We do a deep
11、research on the technique of nodes localization of WSN, and also make a detailed description, classification, analysis and comparison of the staple algorithms at present to sum up their advantages and disadvantages. (2) We give a priority to the study of APIT localization algorithm and analyze its d
12、isadvantages. APIT localization algorithm is a kind of range-free localization and it is more precise in a fixed isomorphic dense networks. However, it has a bigger localization error and a lower coverage rate in a random distributed network, which is because in a random distributed network of senso
13、rs, the nodes are not well distributed, maybe there are lots of nodes in some places, and little in other places, even no one. So the locations of many nodes can not be determined, and has a great influence on its precision. For these problems, a localization method based on mobile anchor node is pr
14、oposed in this thesis, whose idea is that some mobile anchor nodes are introduced into the sensor network, and, during the initialization of the network, try to make the nodes be well distributed through a certain mobile coverage algorithm, then the localization performance of the unknown nodes can
15、be promoted. (3) In most cases, the localization performance can be influenced by the 太原理工大学硕士研究生学位论文 V number of the anchor nodes. And a fair number of anchor nodes can increase precision and coverage rate. So an algorithm based on a network of isomerism sensors to get the optimal number of nodes i
16、s presented in the thesis. Theoretically speaking, the number of needed anchor nodes and unknown nodes, which can cover the whole monitored area in a fixed area, can be worked out through this algorithm in advance. (4) For the ineffective nodes (only one or two adjacent nodes) which can not be localized by APIT algorithm, a specific method is provided in the thesis. Furthermore, we also use RSSI quantized
