【作者】 崔秀锋；

【导师】 冯秀芳；

【作者基本信息】 太原理工大学 ， 计算机应用技术， 2011， 硕士

【摘要】 无线传感器网络(Wireless Sensor Network,WSN)的出现引起了全世界的广泛关注。作为当今信息领域的研究热点,涉及多个学科、多种技术,主要包括：网络通信协议、核心支撑技术、自组织管理、开发与应用。丰富的核心支撑技术使得无线传感器网络构成了一个具体的面向特定应用的网络系统。作为核心支撑技术之一的无线传感器网络节点定位技术是所有应用的基础,因为在不知道相应的位置信息的情况下,传感数据往往是没有任何意义的。在WSN的节点定位算法中,根据不同的分类标准有不同的分类结果,根据定位算法是否需要通过物理测量来获得节点之间的距离(或角度)信息,可以把定位算法分为两类：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,前者总体上能取得较好的定位精度,因此,本文重点研究了基于距离的节点定位算法。本文的主要工作归纳如下：(1)简单介绍无线传感器网络的研究现状和发展动态,深入研究了现有的无线传感器网络节点定位算法的相关知识及基本原理,对这些算法进行介绍、分析、分类和比较,总结各自的优缺点。(2)分析对比了现在常用的测距方式：红外线、超声波、GPS和RSSI等,重点研究了基于RSSI测距的定位算法,它无须额外硬件支持,仅仅利用对接收端无线信号的强度来计算发送节点和接收节点间的距离,基于RSSI的定位算法提供了最廉价的定位方法,所以基于RSSI的定位算法是无线传感器网络定位过程中较常采用的方法,然而,实际应用中,由于多径和非视线传播等造成的信号传播模型的复杂性,往往会导致RSSI测距具有很大的不稳定性,从而造成较大范围的定位误差。针对以上问题,本文提出了利用局部性原理来削减测距的不稳定性,即通过锚节点之间通信来获得其所在位置的的衰减系数。(3)目前,大部分定位算法都是基于二维平面的算法。在实际应用中,节点的分布往往在地形比较复杂的三维空间环境中,二维平面中的算法在应用中会有很多问题。因此,三维空间中节点定位算法十分必要,针对应用范围的问题,本文提出了将RSSI测距扩展到三维的实际应用环境中。(4)由于主客观原因估测得到的多个节点位置可能存在明显错误,本文提出对这些估计位置进行过滤,当多数估计位置比较集中,而少数估计位置离集中位置比较远,我们可认为这几个少数位置是不可靠估计位置,可以除掉,其他位置认为是可靠的,以此来提高定位精度。(5)最后,用实验验证改进后算法的定位性能。采用MATLAB7.1仿真工具对基于RSSI的定位算法在二维空间中(RSSI-2D),基于RSSI的定位算法在三维空间中(RSSI-3D),基于RSSI的改进定位算法在三维空间中(IRSSI-3D)进行仿真实验。仿真结果表明,本文提出的基于RSSI的改进三维定位算法很好地提高了节点定位精度,应用范围广泛。更多还原

【Abstract】 The appearance of Wireless Sensor Network (WSN) caused widespread concern around the world. As the research focus of current information field,it involves many disciplines and mutiple technologies,including network communication protocol, core support technology, self-organization and management, development and application. With the rich core support technology, the WSN constitutes a specific application-oriented network system. The localization technology, as one of the core support technologies,is the basis of all applications. Because, the sensor data is no sense, without the location information.According to different classification criteria, the localization algorithms in WSN have different classification results. Based on the need to get the distance or angle among the nodes information by the physical measurement, location algorithms can be divided into two categories:range-based localization algorithm and range-free localization algorithm.The research shows that the former can achieve high location precision.Therefore, in this thesis, range-based localization algorithm is focused on.Major tasks of the thesis are as follows: (1) The research status and development trends of wireless sensor networks are introdued briefly. In-depth research on the knowledge and basic technique of nodes localization of WSN is given, and also a detailed description, classification, analysis and comparison of the staple algorithms at present are made to sum up their advantages and disadvantages.(2) Ranging methods used commonly are analyzed and compared, including: infrared, ultrasonic, GPS, and RSSI, etc. The localization algorithm based on RSSI distance is focused on, without any additional hardware to support, the distance between sending node and receiving node is computed by using the strength of the wireless receiver signal.The localization algorithm based on RSSI provides the most inexpensive method.So the localization algorithm based on RSSI is used more often.However,in the practical applications, the complexity of the signal model caused by multipath and non line of sight, makes the RSSI ranging great instability,causing a wide range of positioning errors. To solve the above problem, locality principle is proposed to reduce the instability in this thesis.It is that the attenuation coefficient of anchor’s location is obtained by communicatbing between anchors.(3) At present, most of the location algorithms are based on two-dimensional. In practice, the distribution of nodes is often in the three-dimensional space complexity environment. So the algorithm in two-dimensional plane will have many problems. Therefore, the localization algorithm in three-dimensional space is very necessary. In this thesis,the RSSI ranging is proposed to extend the practical application of three-dimensional environment for the problem of application scope.(4) For the estimated location, there maybe an obvious error due to objective and subjective reasons.It is proposed in this paper to filter the error location.When many estimated locations are more concentrated, the few are relatively far away from the central location.The few ones can be considered as unreliable and divided,others are considered as reliable to improve the location accuracy.(5) Finally, the localization performance of improved algorithm is shown by simulation experiments.Using Simulation tool MATLAB 7.1,RSSI-based localization algorithm in two dimensions (RSSI-2D), RSSI-based localization algorithm in three dimensions (RSSI-3D), improved RSSI-based location algorithm in three-dimensional space (IRSSI-3D) were simulated. It is shown by the experiments that the IRSSI-3D algorithm proposed in this thesis has high localization precision and wide applications.更多还原