非视距传播环境下的AOA定位跟踪算法

基于几何结构的单次反射统计信道模型,提出了一种在非视距(NLOS)传播环境下对移动台的到达角(AOA)的定位与跟踪算法.首先利用径向基函数(RBF)神经网络对NLOS误差进行修正,再利用最小二乘(LS)算法进行移动台位置估计,然后配合相关检测距离门对移动台进行跟踪.仿真结果表明,该跟踪算法能够有效地实现移动台的静态定位...     

基于TOA的三维空间定位算法研究

对三维定位算法进行了研究,提出了一种基于到达时间的三维定位算法.其主要思想是用一新变量代替定位估计中的二次项,把非线性估计转化为两次WLS(加权最小二乘)线性估计.该算法结构简单,计算量较小.仿真结果证明了该算法的有效性.     

一种SADOA/AOA混合定位算法及其性能分析

本文提出了一种新的蜂窝网混合定位算法.该算法首先将服务基站智能天线阵列提供的信号路径损失差(SADOA)与到达角(AOA)信息相结合,然后通过WLS算法实现对移动台实际位置的估计.本算法结构简单,计算量较小且无需移动台与基站的时间同步.仿真结果表明,该算法能够有效减小阴影效应造成的估计误差,具有较高的定位精度.     

基于EKF和数据融合的移动台跟踪定位算法

提出一种利用扩展卡尔曼滤波(EKF)算法实现移动台跟踪定位的改进算法。该算法在已获得移动台初始位置估计的基础上,利用 EKF对移动台的运动轨迹进行多次估计,获取多条跟踪轨迹,剔除偏差较大的轨迹并进行加权平均的数据融合处理,获取一条较优轨迹。再结合距离门限值对较优轨迹的点迹进行匹配管理,实现对较优轨迹的平滑处理,获得最优跟踪轨迹。仿真结果表明,该算法计算复杂度低、鲁棒性强,定位精度明显高于传统EKF跟踪定位算法。     

一种智能化区域无线网络的移动台动态定位算法

无线网络影响因素较多,总是无法避免地产生定位误差,为取得更好的可靠性与精准度,针对智能化区域无线网络,提出一种移动台动态定位算法.构建基于到达时延差的约束加权最小二乘算法,获取到达时延差信息,根据移动台对应服务基站获取的移动台到达时延差与到达角度数据,利用约束加权最小二乘算法多次更新定位估计,结合小波变换,架构到达时延差/到达角度混合定位算法,依据智能化区域无线网络环境的到达时延差数据采集情况,将估算出的移动台大致位置设定为不同种类定位结果,通过多次估算实现移动台动态定位.选取不同无线网络环境展开移动台动态定位仿真,分别从到达时延测量偏差、区域半径以及移动台与其服务基站间距等角度验证算法定位效果,由实验结果可知,所提算法具有理想的干扰因素抑制能力,且定位精准度较高.     

运用最优化原理的新型非视距抑制无线定位算法

无线定位中非视距(NLOS)误差的存在会显著降低传统定位算法的精度,因此论文提出了一种运用最优化原理的定位算法以对抗NLOS误差.该算法适用于存在固定节点与移动节点的无线传感网系统,并结合距离加权思想将NLOS环境中的定位建模为二次规划问题,最终得到节点的最小二乘位置估计.分析表明在固定节点数量较多或者存在视距(LOS)传输固定节点时,该算法可以显著削弱NLOS误差的影响.计算机仿真证实了这一分析,其结果表明,在NLOS环境下论文所提出的算法性能优于现有其他定位算法,同时该算法还具有不受固定节点数目限制和复杂度较低等优点.     

一种NLOS环境下的TDOA/AOA定位算法

在LOS环境下,Chan算法有着较好的定位精度,基于Chan算法的到达时间差/到达角(TDOA/AOA)算法比Chan算法有了进一步提高。但是在NLOS环境下,这些算法的精度都将大大下降,由于AOA的测量值有较大误差,TDOA/AOA方法的精度甚至低于Chan算法。并且这些算法的主要缺点是在第一次加权最小二乘法(WLS)中把移动台的横坐标、纵坐标与移动台到服务基站的距离作为三个相互独立的变量,忽略了三者之间的相关性,因此要进行第二次WLS才能得到定位结果,且最终的解为二值根。对误差的均值和方差进行了估计,修正了TDOA与AOA测量值,用Kalman滤波算法对AOA的值进行了估计,利用移动台坐标与AOA之间的关系将三个变量简化为一个,只需一次WLS即可求得唯一解,减少了计算量,消除了根的模糊性。仿真结果表明,该方法简单,计算量小,有较高的定位精度和较好的稳健性,性能优于Chan算法和基于Chan算法的TDOA/AOA算法。     

无线蜂窝系统中的定位与技术研究

无线网络中的定位现今主要是由基于移动台的定位技术、基于移动网络的定位技术、基于GPS定位技术三种类型来实现。本文将重点介绍移动台的定位和移动网络的定位两种定位技术。移动台定位包括估计定位参数,根据参数选择合适的算法求出移动台的位置。移动网络定位主要是根据利用信号到达的方位角(AOA)进行无线定位,根据利用信号到达时间(TOA)进行无线定位,根据利用信号到达时间差(TDOA)进行无线定位。     

基于小波变换的场强定位算法

利用服务基站与移动台之间的场强测量值来进行移动台位置估计,并从场强信号传播模型和定位算法出发,提出了一种基于小波变换的改进场强定位算法。通过小波变换来修正传播误差,然后利用LS算法进行定位。仿真结果表明,该基于场强的移动台定位方法在一定程度上提高了定位精度,定位效果明显优于Chan算法、LS算法、Taylor算法。     

基于BP神经网络的定位跟踪算法

提出了一种在NLOS环境下对移动台的定位与跟踪算法。利用BP神经网络对TDOA测量值中NLOS误差进行修正,再利用Chan算法进行移动台位置估计,配合相关检测距离门对移动台进行跟踪。仿真结果表明,该跟踪算法能够有效地实现移动台的静态定位与动态跟踪,性能优于基于Chan算法、LS算法、Taylor算法的静态定位与动态跟踪。     

What knows where you are?

What's been the biggest change when it comes to personal security? Indisputably, the advent of the cellular phone. In daily life as well, whether reporting suspicious activity or touching base with the kids, more and more people rely on their wireless phones. Cellular service in the US has grown slowly and steadily, with subscribers increasing by 30 to 40 per cent a year. However, cellular callers can be at a disadvantage when dialing 911. The phone being mobile rules out a simple database relationship between phone number and location. This means that 911 calls made from wireless phones don't automatically reach the closest emergency service and that the response time can be far longer. In 1996, concerned policymakers responded with Enhanced 911 (E-911) legislation. Phase one of the Federal Communications Commission (FCC) directive specified that by April 1998, wireless carriers had to be able to report a wireless 911 caller's telephone number and the receiving antenna's location. The article looks at some of the technical difficulties still encountered, people tracking devices, privacy, and smart card/wireless devices merger.     

Inter-organizational Emergency Medical Services: Case Study of Rural Wireless Deployment and Management

Over the last two decades, use of mobile communications for emergency services (e.g. 911) has grown exponentially. This rise of mobile networks has increased reliance on new private and public partnerships to deliver these time critical services. Drawing upon complex systems theory and Inter-organizational Systems (IOS) dynamics, a framework is developed for investigating technology, organizational and policy dimensions of Emergency Medical Services (EMS). The case study for this investigation is rural Minnesota, where a series of semi-structured interviews were conducted and supplemented by analysis of candidate EMS system evaluations. The twofold objectives of the study were to explore the nature of inter-organizational dynamics in this setting and to set forth an architecture for measuring and enhancing performance. Key technology concerns included gaps in wireless coverage, complex system upgrades, and lagging integration of wireless communications into existing infrastructures. These issues were intertwined with organizational aspects, such as the challenges in developing coordinated relationships among agencies and between the public and private sectors. Several policy levers were also influential, such as federal standards that had been set forth for E-911 location information and funding initiatives in the transportation area. The final section draws upon these findings to suggest an EMS architecture that portrays the entire system as well as critical IOS linkages. While IOS has traditionally examined supply chains, these findings are aimed to contribute to understanding more complex, dynamic and heterogeneous socio-technical processes. The paper concludes with a discussion of management and research implications.     

Multi-agent location system in wireless networks

In this paper we propose a flexible Multi-Agent Architecture together with a methodology for indoor location which allows us to locate any mobile station (MS) such as a Laptop, Smartphone, Tablet or a robotic system in an indoor environment using wireless technology. Our technology is complementary to the GPS location finder as it allows us to locate a mobile system in a specific room on a specific floor using the Wi-Fi networks.The idea is that any MS will have an agent known at a Fuzzy Location Software Agent (FLSA) with a minimum capacity processing at its disposal which collects the power received at different Access Points distributed around the floor and establish its location on a plan of the floor of the building. In order to do so it will have to communicate with the Fuzzy Location Manager Software Agent (FLMSA). The FLMSAs are local agents that form part of the management infrastructure of the Wi-Fi network of the Organization.The FLMSA implements a location estimation methodology divided into three phases (measurement, calibration and estimation) for locating mobile stations (MS). Our solution is a fingerprint-based positioning system that overcomes the problem of the relative effect of doors and walls on signal strength and is independent of the network device manufacturer.In the measurement phase, our system collects received signal strength indicator (RSSI) measurements from multiple access points. In the calibration phase, our system uses these measurements in a normalization process to create a radio map, a database of RSS patterns. Unlike traditional radio map-based methods, our methodology normalizes RSS measurements collected at different locations on a floor. In the third phase, we use Fuzzy Controllers to locate an MS on the plan of the floor of a building.Experimental results demonstrate the accuracy of the proposed method. From these results it is clear that the system is highly likely to be able to locate an MS in a room or adjacent room.     

Location awareness-based intelligent multi-agent technology

In this paper, we propose an advanced location awareness-based intelligent multi-agent technology that allows multiple users to share various user-centric mobile multimedia contents. This paper mainly focuses on (1) mobile station-based mixed-web map module via mobile mash-up technology, (2) a new location-based mobile multimedia technology using ubiquitous sensor Net.-based five senses content, and (3) location awareness-based intelligent multi-agent technology that includes a location-based integrated retrieval agent, a mobile social network (MSN)-based multi-user detection agent and user-centric automatic mobile multimedia recommender agent. This paper aims at validating and inspecting the usability, suitability, and applicability of the suggested technology via various performance evaluation experiments.     

Geolocation and assisted GPS

Currently in development, numerous geolocation technologies can pinpoint a person's or object's position on the Earth. Knowledge of the spatial distribution of wireless callers will facilitate the planning, design, and operation of next generation broadband wireless networks. Mobile users will gain the ability to get local traffic information and detailed directions to gas stations, restaurants, hotels, and other services. Police and rescue teams will be able to quickly and precisely locate people who are lost or injured but cannot give their precise location. Companies will use geolocation based applications to track personnel, vehicles, and other assets. The driving force behind the development of this technology is a US Federal Communications Commission (FCC) mandate stating that by 1 October 2001 all wireless carriers must provide the geolocation of an emergency 911 caller to the appropriate public safety answering point. Location technologies requiring new modified, or upgraded mobile stations must determine the caller's longitude and latitude within 50 meters for 67 percent of emergency calls, and within 150 meters for 95 percent of the calls. Otherwise, they must do so within 100 meters and 300 meters, respectively, for the same percentage of calls. Currently deployed wireless technology can locate 911 calls within an area no smaller than 10 to 15 square kilometers. It is argued that assisted-GPS technology offers superior accuracy, availability, and coverage at a reasonable cost     

基于单反射模型的混合定位算法研究

针对现有定位算法抗非视距能力弱、且对移动台求解时往往需要一个比较精确初始解的问题,利用移动台和散射体的几何位置关系,基于单次反射圆模型提出了一种抑制非视距误差的波达时间/波达角混合定位算法。定位过程中将散射体视为虚拟基站,根据最大散射半径确定移动台的可能位置范围,在该范围内搜寻所有满足约束条件的位置点,对这些点使用加权平均处理方式以提高定位精度,最后结果即为移动台估计位置。计算机仿真表明了算法的有效性。。     

对无线网络移动认证协议的分析与改进

文献[5,6]利用基于椭圆曲线的信任授权机制设计了适用于无线移动设备的高效认证体制。从匿名性和会话密钥更新的角度分析该方案的缺陷。在不增加本地注册中心HLR、漫游地注册中心VLR和移动终端MS额外负担的前提下,提出了改进方案,加强方案的匿名性和密钥更新能力:一方面VLR无法获悉MS的身份信息;另一方面,MS和VLR可以更新它们的会话密钥,即使在HLR离线的情况下。提出的改进方案保持了原方案的高效性和其它优点。     

Reliability and survivability of wireless and mobile networks

The world is becoming more dependent on wireless and mobile services, but the ability of wireless network infrastructures to handle the growing demand is questionable. As wireless and mobile services grow, weaknesses in network infrastructures become clearer. Failures not only affect current voice and data use but could also limit emerging wireless applications such as e-commerce and high-bandwidth Internet access. As wireless and mobile systems play greater roles in emergency response, including 911 and enhanced 911 services, network failures take on life-or-death significance. Therefore, in addition to directing some attention to designing survivable wireless and mobile networks, developers must also keep in mind that increasingly pervasive and demanding services will further escalate the importance of reliability and survivability requirements. The authors explain several options providers must consider to decrease the number of network failures and to cope with failures when they do occur     

Wireless location privacy protection

After more than two decades of hype, computing and communication technologies are finally converging. Java-enabled cell phones run a host of powerful applications including mobile Internet access, while many notebook computers offer high-speed wireless connectivity as a standard feature. The big decision when purchasing a PDA is whether to get integrated cellular service or Wi-Fi capability. Location-based services are emerging as the next killer app in personal wireless devices, but there are few safeguards on location privacy. In fact, the demand for improved public safety is pushing regulation in the opposite direction. Today, when a person reports an emergency from a landline phone by dialing 911 in the United States or 112 in Europe, the system displays the caller's phone number and address to the dispatcher. The US Federal Communications Commission has mandated that, by December 2005, all cellular carriers be able to identify the location of emergency callers using mobile phones to within 50 to 100 meters. However, how cellular carriers and other businesses will use this capability remains open to question. The article looks at some of the areas this capability affects, including: privacy risks; economic damages; location-based spam; intermittent connectivity; user interfaces; network privacy; and privacy protection.     

基于SUPL的WCDMA定位技术研究

定位技术是第三代移动通信系统中一个非常有前景的技术。本文首先比较了定位技术中控制面实现方案与用户面实现方案的区别,分析了一种基于用户面的定位技术方案-SUPL方案,阐述了SUPL中采用的定位技术、网络架构及其各个关键网络元素的功能,并以一个业务流程为例说明了业务实现的步骤,最后提出了一种同时支持控制面与用户面定位技术的过渡方案,并对SUPL的应用前景进行了展望。