RADAR: an in-building RF-based user location and tracking system
26 Mar 2000-Vol. 2, pp 775-784
TL;DR: RADAR is presented, a radio-frequency (RF)-based system for locating and tracking users inside buildings that combines empirical measurements with signal propagation modeling to determine user location and thereby enable location-aware services and applications.
Abstract: The proliferation of mobile computing devices and local-area wireless networks has fostered a growing interest in location-aware systems and services. In this paper we present RADAR, a radio-frequency (RF)-based system for locating and tracking users inside buildings. RADAR operates by recording and processing signal strength information at multiple base stations positioned to provide overlapping coverage in the area of interest. It combines empirical measurements with signal propagation modeling to determine user location and thereby enable location-aware services and applications. We present experimental results that demonstrate the ability of RADAR to estimate user location with a high degree of accuracy.
Citations
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01 Aug 2000
TL;DR: The randomized algorithm used by beacons to transmit information, the use of concurrent radio and ultrasonic signals to infer distance, the listener inference algorithms to overcome multipath and interference, and practical beacon configuration and positioning techniques that improve accuracy are described.
Abstract: This paper presents the design, implementation, and evaluation of Cricket, a location-support system for in-building, mobile, location-dependent applications. It allows applications running on mobile and static nodes to learn their physical location by using listeners that hear and analyze information from beacons spread throughout the building. Cricket is the result of several design goals, including user privacy, decentralized administration, network heterogeneity, and low cost. Rather than explicitly tracking user location, Cricket helps devices learn where they are and lets them decide whom to advertise this information to; it does not rely on any centralized management or control and there is no explicit coordination between beacons; it provides information to devices regardless of their type of network connectivity; and each Cricket device is made from off-the-shelf components and costs less than U.S. $10. We describe the randomized algorithm used by beacons to transmit information, the use of concurrent radio and ultrasonic signals to infer distance, the listener inference algorithms to overcome multipath and interference, and practical beacon configuration and positioning techniques that improve accuracy. Our experience with Cricket shows that several location-dependent applications such as in-building active maps and device control can be developed with little effort or manual configuration.
4,123 citations
Cites methods from "RADAR: an in-building RF-based user..."
...The RADAR system implements a location service utilizing the information obtained from an already existing RF data network [4]....
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01 Nov 2007
TL;DR: Comprehensive performance comparisons including accuracy, precision, complexity, scalability, robustness, and cost are presented.
Abstract: Wireless indoor positioning systems have become very popular in recent years. These systems have been successfully used in many applications such as asset tracking and inventory management. This paper provides an overview of the existing wireless indoor positioning solutions and attempts to classify different techniques and systems. Three typical location estimation schemes of triangulation, scene analysis, and proximity are analyzed. We also discuss location fingerprinting in detail since it is used in most current system or solutions. We then examine a set of properties by which location systems are evaluated, and apply this evaluation method to survey a number of existing systems. Comprehensive performance comparisons including accuracy, precision, complexity, scalability, robustness, and cost are presented.
4,123 citations
Additional excerpts
...[35] proposed an in-building user location and...
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TL;DR: This work reviews localization techniques and evaluates the effectiveness of a very simple connectivity metric method for localization in outdoor environments that makes use of the inherent RF communications capabilities of these devices.
Abstract: Instrumenting the physical world through large networks of wireless sensor nodes, particularly for applications like environmental monitoring of water and soil, requires that these nodes be very small, lightweight, untethered, and unobtrusive. The problem of localization, that is, determining where a given node is physically located in a network, is a challenging one, and yet extremely crucial for many of these applications. Practical considerations such as the small size, form factor, cost and power constraints of nodes preclude the reliance on GPS of all nodes in these networks. We review localization techniques and evaluate the effectiveness of a very simple connectivity metric method for localization in outdoor environments that makes use of the inherent RF communications capabilities of these devices. A fixed number of reference points in the network with overlapping regions of coverage transmit periodic beacon signals. Nodes use a simple connectivity metric, which is more robust to environmental vagaries, to infer proximity to a given subset of these reference points. Nodes localize themselves to the centroid of their proximate reference points. The accuracy of localization is then dependent on the separation distance between two-adjacent reference points and the transmission range of these reference points. Initial experimental results show that the accuracy for 90 percent of our data points is within one-third of the separation distance. However, future work is needed to extend the technique to more cluttered environments.
3,723 citations
Cites methods from "RADAR: an in-building RF-based user..."
...One approach for RF-based localization is to use measured signal strength of received beacon signals to estimate distance, as in the RADAR system [6], with an outdoor radio signal propagation model....
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...In the RADAR system [6], Bahl et.al., suggest estimating distance based on signal strength in indoor environments....
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...The major drawback of this technique, as with RADAR [6] is the substantial effort needed for generation of the signal signature database....
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...The major drawback of this technique, as with the RF mapping approach in RADAR [6], is the substantial effort needed for generation of the signal signature database....
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...One approach for RF-based localization is to use measured signal strength of received beacon signals to estimat e distance, as in the RADAR system [6], with an outdoor radio signal propagation model....
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TL;DR: This survey and taxonomy of location systems for mobile-computing applications describes a spectrum of current products and explores the latest in the field to help developers of location-aware applications better evaluate their options when choosing a location-sensing system.
Abstract: This survey and taxonomy of location systems for mobile-computing applications describes a spectrum of current products and explores the latest in the field. To make sense of this domain, we have developed a taxonomy to help developers of location-aware applications better evaluate their options when choosing a location-sensing system. The taxonomy may also aid researchers in identifying opportunities for new location-sensing techniques.
3,237 citations
Cites methods from "RADAR: an in-building RF-based user..."
...A Microsoft Research group has developed RADAR, a building-wide tracking system based on the IEEE 802.11 WaveLAN wireless networking technology [ 3 ]....
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16 Jul 2001
TL;DR: A novel approach to the localization of sensors in an ad-hoc network that enables sensor nodes to discover their locations using a set distributed iterative algorithms is described.
Abstract: The recent advances in radio and em beddedsystem technologies have enabled the proliferation of wireless microsensor networks. Such wirelessly connected sensors are released in many diverse environments to perform various monitoring tasks. In many such tasks, location awareness is inherently one of the most essential system parameters. It is not only needed to report the origins of events, but also to assist group querying of sensors, routing, and to answer questions on the network coverage. In this paper we present a novel approach to the localization of sensors in an ad-hoc network. We describe a system called AHLoS (Ad-Hoc Localization System) that enables sensor nodes to discover their locations using a set distributed iterative algorithms. The operation of AHLoS is demonstrated with an accuracy of a few centimeters using our prototype testbed while scalability and performance are studied through simulation.
2,931 citations
Cites background from "RADAR: an in-building RF-based user..."
...The RADAR system [1] can track the location of users within a building....
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References
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Book•
01 Jan 1990TL;DR: The updated new edition of the classic Introduction to Algorithms is intended primarily for use in undergraduate or graduate courses in algorithms or data structures and presents a rich variety of algorithms and covers them in considerable depth while making their design and analysis accessible to all levels of readers.
Abstract: From the Publisher:
The updated new edition of the classic Introduction to Algorithms is intended primarily for use in undergraduate or graduate courses in algorithms or data structures. Like the first edition,this text can also be used for self-study by technical professionals since it discusses engineering issues in algorithm design as well as the mathematical aspects.
In its new edition,Introduction to Algorithms continues to provide a comprehensive introduction to the modern study of algorithms. The revision has been updated to reflect changes in the years since the book's original publication. New chapters on the role of algorithms in computing and on probabilistic analysis and randomized algorithms have been included. Sections throughout the book have been rewritten for increased clarity,and material has been added wherever a fuller explanation has seemed useful or new information warrants expanded coverage.
As in the classic first edition,this new edition of Introduction to Algorithms presents a rich variety of algorithms and covers them in considerable depth while making their design and analysis accessible to all levels of readers. Further,the algorithms are presented in pseudocode to make the book easily accessible to students from all programming language backgrounds.
Each chapter presents an algorithm,a design technique,an application area,or a related topic. The chapters are not dependent on one another,so the instructor can organize his or her use of the book in the way that best suits the course's needs. Additionally,the new edition offers a 25% increase over the first edition in the number of problems,giving the book 155 problems and over 900 exercises thatreinforcethe concepts the students are learning.
21,651 citations
Book•
15 Jan 1996
TL;DR: WireWireless Communications: Principles and Practice, Second Edition is the definitive modern text for wireless communications technology and system design as discussed by the authors, which covers the fundamental issues impacting all wireless networks and reviews virtually every important new wireless standard and technological development, offering especially comprehensive coverage of the 3G systems and wireless local area networks (WLANs).
Abstract: From the Publisher:
The indispensable guide to wireless communicationsnow fully revised and updated!
Wireless Communications: Principles and Practice, Second Edition is the definitive modern text for wireless communications technology and system design. Building on his classic first edition, Theodore S. Rappaport covers the fundamental issues impacting all wireless networks and reviews virtually every important new wireless standard and technological development, offering especially comprehensive coverage of the 3G systems and wireless local area networks (WLANs) that will transform communications in the coming years. Rappaport illustrates each key concept with practical examples, thoroughly explained and solved step by step.
Coverage includes:
An overview of key wireless technologies: voice, data, cordless, paging, fixed and mobile broadband wireless systems, and beyond
Wireless system design fundamentals: channel assignment, handoffs, trunking efficiency, interference, frequency reuse, capacity planning, large-scale fading, and more
Path loss, small-scale fading, multipath, reflection, diffraction, scattering, shadowing, spatial-temporal channel modeling, and microcell/indoor propagation
Modulation, equalization, diversity, channel coding, and speech coding
New wireless LAN technologies: IEEE 802.11a/b, HIPERLAN, BRAN, and other alternatives
New 3G air interface standards, including W-CDMA, cdma2000, GPRS, UMTS, and EDGE
Bluetooth wearable computers, fixed wireless and Local Multipoint Distribution Service (LMDS), and other advanced technologies
Updated glossary of abbreviations and acronyms, and a thorolist of references
Dozens of new examples and end-of-chapter problems
Whether you're a communications/network professional, manager, researcher, or student, Wireless Communications: Principles and Practice, Second Edition gives you an in-depth understanding of the state of the art in wireless technologytoday's and tomorrow's.
17,102 citations
01 Jun 1984
TL;DR: A dynamic index structure called an R-tree is described which meets this need, and algorithms for searching and updating it are given and it is concluded that it is useful for current database systems in spatial applications.
Abstract: In order to handle spatial data efficiently, as required in computer aided design and geo-data applications, a database system needs an index mechanism that will help it retrieve data items quickly according to their spatial locations However, traditional indexing methods are not well suited to data objects of non-zero size located m multi-dimensional spaces In this paper we describe a dynamic index structure called an R-tree which meets this need, and give algorithms for searching and updating it. We present the results of a series of tests which indicate that the structure performs well, and conclude that it is useful for current database systems in spatial applications
7,336 citations
"RADAR: an in-building RF-based user..." refers background in this paper
...There is a fair amount of database research literature that describes efficient data structures and algorithms for such multidimensional searches (e.g., R-Tree [ Gut84 ], X-Tree [Ber96], optimal k-nearest neighbor search [Sei98], etc.) However, we chose a simple linear-time search algorithm because our relatively small data set and dimensionality (at most 3, as explained in Section 4) did not warrant the complexity of the aforementioned ......
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TL;DR: In this paper, the authors used the representations of the noise currents given in Section 2.8 to derive some statistical properties of I(t) and its zeros and maxima.
Abstract: In this section we use the representations of the noise currents given in section 2.8 to derive some statistical properties of I(t). The first six sections are concerned with the probability distribution of I(t) and of its zeros and maxima. Sections 3.7 and 3.8 are concerned with the statistical properties of the envelope of I(t). Fluctuations of integrals involving I2(t) are discussed in section 3.9. The probability distribution of a sine wave plus a noise current is given in 3.10 and in 3.11 an alternative method of deriving the results of Part III is mentioned. Prof. Uhlenbeck has pointed out that much of the material in this Part is closely connected with the theory of Markoff processes. Also S. Chandrasekhar has written a review of a class of physical problems which is related, in a general way, to the present subject.22
5,806 citations
"RADAR: an in-building RF-based user..." refers methods in this paper
...The second model we considered was the Rician distribution model [ Ric44 ]....
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Book•
01 Jan 1995
TL;DR: This chapter discusses the development of Hardware and Software for Computer Graphics, and the design methodology of User-Computer Dialogues, which led to the creation of the Simple Raster Graphics Package.
Abstract: 1 Introduction Image Processing as Picture Analysis The Advantages of Interactive Graphics Representative Uses of Computer Graphics Classification of Applications Development of Hardware and Software for Computer Graphics Conceptual Framework for Interactive Graphics 2 Programming in the Simple Raster Graphics Package (SRGP)/ Drawing with SRGP/ Basic Interaction Handling/ Raster Graphics Features/ Limitations of SRGP/ 3 Basic Raster Graphics Algorithms for Drawing 2d Primitives Overview Scan Converting Lines Scan Converting Circles Scan Convertiing Ellipses Filling Rectangles Fillign Polygons Filling Ellipse Arcs Pattern Filling Thick Primiives Line Style and Pen Style Clipping in a Raster World Clipping Lines Clipping Circles and Ellipses Clipping Polygons Generating Characters SRGP_copyPixel Antialiasing 4 Graphics Hardware Hardcopy Technologies Display Technologies Raster-Scan Display Systems The Video Controller Random-Scan Display Processor Input Devices for Operator Interaction Image Scanners 5 Geometrical Transformations 2D Transformations Homogeneous Coordinates and Matrix Representation of 2D Transformations Composition of 2D Transformations The Window-to-Viewport Transformation Efficiency Matrix Representation of 3D Transformations Composition of 3D Transformations Transformations as a Change in Coordinate System 6 Viewing in 3D Projections Specifying an Arbitrary 3D View Examples of 3D Viewing The Mathematics of Planar Geometric Projections Implementing Planar Geometric Projections Coordinate Systems 7 Object Hierarchy and Simple PHIGS (SPHIGS) Geometric Modeling Characteristics of Retained-Mode Graphics Packages Defining and Displaying Structures Modeling Transformations Hierarchical Structure Networks Matrix Composition in Display Traversal Appearance-Attribute Handling in Hierarchy Screen Updating and Rendering Modes Structure Network Editing for Dynamic Effects Interaction Additional Output Features Implementation Issues Optimizing Display of Hierarchical Models Limitations of Hierarchical Modeling in PHIGS Alternative Forms of Hierarchical Modeling 8 Input Devices, Interaction Techniques, and Interaction Tasks Interaction Hardware Basic Interaction Tasks Composite Interaction Tasks 9 Dialogue Design The Form and Content of User-Computer Dialogues User-Interfaces Styles Important Design Considerations Modes and Syntax Visual Design The Design Methodology 10 User Interface Software Basic Interaction-Handling Models Windows-Management Systems Output Handling in Window Systems Input Handling in Window Systems Interaction-Technique Toolkits User-Interface Management Systems 11 Representing Curves and Surfaces Polygon Meshes Parametric Cubic Curves Parametric Bicubic Surfaces Quadric Surfaces 12 Solid Modeling Representing Solids Regularized Boolean Set Operations Primitive Instancing Sweep Representations Boundary Representations Spatial-Partitioning Representations Constructive Solid Geometry Comparison of Representations User Interfaces for Solid Modeling 13 Achromatic and Colored Light Achromatic Light Chromatic Color Color Models for Raster Graphics Reproducing Color Using Color in Computer Graphics 14 The Quest for Visual Realism Why Realism? Fundamental Difficulties Rendering Techniques for Line Drawings Rendering Techniques for Shaded Images Improved Object Models Dynamics Stereopsis Improved Displays Interacting with Our Other Senses Aliasing and Antialiasing 15 Visible-Surface Determination Functions of Two Variables Techniques for Efficient Visible-Surface Determination Algorithms for Visible-Line Determination The z-Buffer Algorithm List-Priority Algorithms Scan-Line Algorithms Area-Subdivision Algorithms Algorithms for Octrees Algorithms for Curved Surfaces Visible-Surface Ray Tracing 16 Illumination And Shading Illumination Modeling Shading Models for Polygons Surface Detail Shadows Transparency Interobject Reflections Physically Based Illumination Models Extended Light Sources Spectral Sampling Improving the Camera Model Global Illumination Algorithms Recursive Ray Tracing Radiosity Methods The Rendering Pipeline 17 Image Manipulation and Storage What Is an Image? Filtering Image Processing Geometric Transformations of Images Multipass Transformations Image Compositing Mechanisms for Image Storage Special Effects with Images Summary 18 Advanced Raster Graphic Architecture Simple Raster-Display System Display-Processor Systems Standard Graphics Pipeline Introduction to Multiprocessing Pipeline Front-End Architecture Parallel Front-End Architectures Multiprocessor Rasterization Architectures Image-Parallel Rasterization Object-Parallel Rasterization Hybrid-Parallel Rasterization Enhanced Display Capabilities 19 Advanced Geometric and Raster Algorithms Clipping Scan-Converting Primitives Antialiasing The Special Problems of Text Filling Algorithms Making copyPixel Fast The Shape Data Structure and Shape Algebra Managing Windows with bitBlt Page Description Languages 20 Advanced Modeling Techniques Extensions of Previous Techniques Procedural Models Fractal Models Grammar-Based Models Particle Systems Volume Rendering Physically Based Modeling Special Models for Natural and Synthetic Objects Automating Object Placement 21 Animation Conventional and Computer-Assisted Animation Animation Languages Methods of Controlling Animation Basic Rules of Animation Problems Peculiar to Animation Appendix: Mathematics for Computer Graphics Vector Spaces and Affine Spaces Some Standard Constructions in Vector Spaces Dot Products and Distances Matrices Linear and Affine Transformations Eigenvalues and Eigenvectors Newton-Raphson Iteration for Root Finding Bibliography Index 0201848406T04062001
5,692 citations
"RADAR: an in-building RF-based user..." refers methods in this paper
...the Cohen-Sutherland line-clipping algorithm [ Fol90 ], we computed the number of walls that obstructed the direct line between the base stations and the locations where we had collected the empirical signal strength data....
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