Location determination of a mobile device using IEEE 802.11b access point signals
16 Mar 2003-Vol. 3, pp 1987-1992
TL;DR: This paper exploits the fact that the strength of the signals that a device will receive from different access points will vary with location, and builds a database of signal strength information for various locations, and uses this information to determine which location a given test data comes from.
Abstract: Wireless LANs are becoming increasingly popular today, particularly those based on IEEE 802.11b standard. We study the problem of determining the location of a mobile device, which is communicating through a WLAN. We exploit the fact that the strength of the signals that a device will receive from different access points will vary with location. We build a database of signal strength information for various locations, and use this information to determine which location a given test data comes from. The problem is complicated because RF signals are affected by the noise, interference, multi-path effect, and random movement in the environment. We find that in spite of this randomness, the signal information is sufficient to detect the position of mobile device with certain error margin.
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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
Cites background from "Location determination of a mobile ..."
...It is reported in [42] that neural networks give an error of 1 m with 72% probability....
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07 Mar 2004
TL;DR: This paper develops the framework for analyzing a simple positioning system that employs the Euclidean distance between a sample signal vector and the location fingerprints of an area stored in a database and analyzes the effect of the number of access points that are visible and radio propagation parameters on the performance of the positioning system.
Abstract: In previous years, positioning systems for indoor areas using the existing wireless local area network infrastructure have been suggested. Such systems make use of location fingerprinting rather than time or direction of arrival techniques for determining the location of mobile stations. While experimental results related to such positioning systems have been presented, there is a lack of analytical models that can be used as a framework for designing and deploying the positioning systems. In this paper, we present an analytical model for analyzing such positioning systems. We develop the framework for analyzing a simple positioning system that employs the Euclidean distance between a sample signal vector and the location fingerprints of an area stored in a database. We analyze the effect of the number of access points that are visible and radio propagation parameters on the performance of the positioning system and provide some preliminary guidelines on its design.
712 citations
Cites background or methods from "Location determination of a mobile ..."
...A modification to the nearest neighbor classifier using an additional information of standard deviation fingerprint was studied in [31]....
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...The Euclidean distance is a well known distance metric used in [13, 16, 31] to classify the positions....
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...To create a basis fingerprint such as in [13, 31], a number of samples of vectors of signal strength are collected over a window of time for each position....
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...The simplest closeness metric is a distance measurement in signal space denoted as the Dist(·) function [31]....
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...Extra fingerprint information such as standard deviation for each RSS element, which is suggested in [31], may be added into the location fingerprint as another vector of standard deviations: D = (σ1, σ2, ....
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TL;DR: The state-of-the-art positioning designs are surveyed, focusing specifically on signal processing techniques in network-aided positioning, to provide new directions for future research.
Abstract: Wireless positioning has attracted much research attention and has become increasingly important in recent years. Wireless positioning has been found very useful for other applications besides E911 service, ranging from vehicle navigation and network optimization to resource management and automated billing. Although many positioning devices and services are currently available, it is necessary to develop an integrated and seamless positioning platform to provide a uniform solution for different network configurations. This article surveys the state-of-the-art positioning designs, focusing specifically on signal processing techniques in network-aided positioning. It serves as a tutorial for researchers and engineers interested in this rapidly growing field. It also provides new directions for future research for those who have been working in this field for many years.
604 citations
Cites methods from "Location determination of a mobile ..."
...Although signal processing may accelerate the development of indoor geolocation methods, mobile positioning also can be achieved by exploiting timing protocols as suggested in [48]....
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19 Mar 2009
TL;DR: A unified mathematical formulation of radio map database and location estimation is presented, point out the equivalence of some methods from the literature, and present some new variants.
Abstract: The term “location fingerprinting” covers a wide variety of methods for determining receiver position using databases of radio signal strength measurements from different sources. In this work we present a survey of location fingerprinting methods, including deterministic and probabilistic methods for static estimation, as well as filtering methods based on Bayesian filter and Kalman filter. We present a unified mathematical formulation of radio map database and location estimation, point out the equivalence of some methods from the literature, and present some new variants. A set of tests in an indoor positioning scenario using WLAN signal strengths is performed to determine the influence of different calibration and location method parameters. In the tests, the probabilistic method with the kernel function approximation of signal strength histograms was the best static positioning method. Moreover, all filters improved the results significantly over the static methods.
571 citations
Cites methods from "Location determination of a mobile ..."
...The mean of these measurements is denoted by ȳj which is the jth component of vector ȳ....
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Dissertation•
01 Jan 2005TL;DR: This dissertation presents beacon interference avoidance and detection algorithms, as well as outlier rejection algorithms to prevent and filter out outlier distance estimates caused by uncoordinated beacon transmissions.
Abstract: Indoor environments present opportunities for a rich set of location-aware applications such as navigation tools for humans and robots, interactive virtual games, resource discovery, asset tracking, location-aware sensor networking etc Typical indoor applications require better accuracy than what current outdoor location systems provide Outdoor location technologies such as GPS have poor indoor performance because of the harsh nature of indoor environments Further, typical indoor applications require different types of location information such as physical space, position and orientation
This dissertation describes the design and implementation of the Cricket indoor location system that provides accurate location in the form of user space, position and orientation to mobile and sensor network applications
Cricket consists of location beacons that are attached to the ceiling of a building, and receivers, called listeners, attached to devices that need location Each beacon periodically transmits its location information in an RF message At the same time, the beacon also transmits an ultrasonic pulse The listeners listen to beacon transmissions and measure distances to nearby beacons, and use these distances to compute their own locations This active-beacon passive-listener architecture is scalable with respect to the number of users, and enables applications that preserve user privacy
This dissertation describes how Cricket achieves accurate distance measurements between beacons and listeners Once the beacons are deployed, the MAT and AFL algorithms, described in this dissertation, use measurements taken at a mobile listener to configure the beacons with a coordinate assignment that reflects the beacon layout This dissertation presents beacon interference avoidance and detection algorithms, as well as outlier rejection algorithms to prevent and filter out outlier distance estimates caused by uncoordinated beacon transmissions
The Cricket listeners can measure distances with an accuracy of 5 cm The listeners can detect boundaries with an accuracy of 1 cm Cricket has a position estimation accuracy of 10 cm and an orientation accuracy of 3 degrees (Copies available exclusively from MIT Libraries, Rm 14-0551, Cambridge, MA 02139-4307 Ph 617-253-5668; Fax 617-253-1690)
527 citations
References
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Book•
16 Jul 1998
TL;DR: Thorough, well-organized, and completely up to date, this book examines all the important aspects of this emerging technology, including the learning process, back-propagation learning, radial-basis function networks, self-organizing systems, modular networks, temporal processing and neurodynamics, and VLSI implementation of neural networks.
Abstract: From the Publisher:
This book represents the most comprehensive treatment available of neural networks from an engineering perspective. Thorough, well-organized, and completely up to date, it examines all the important aspects of this emerging technology, including the learning process, back-propagation learning, radial-basis function networks, self-organizing systems, modular networks, temporal processing and neurodynamics, and VLSI implementation of neural networks. Written in a concise and fluid manner, by a foremost engineering textbook author, to make the material more accessible, this book is ideal for professional engineers and graduate students entering this exciting field. Computer experiments, problems, worked examples, a bibliography, photographs, and illustrations reinforce key concepts.
29,130 citations
"Location determination of a mobile ..." refers methods in this paper
...If a sample point lies within no such region, we say that we are unable to classify it. If a sample point lies within more than one such region, we break the tie by choosing the region whose center is nearest to . 2) Neural Network: Our second classifier is a Backpropagation neural network [ 10 ]....
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26 Mar 2000
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.
8,667 citations
"Location determination of a mobile ..." refers methods in this paper
...Similar work has been done previously by Bahl and Padmanabhan [8], who have used IEEE 802....
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...Similar work has been done previously by Bahl and Padmanabhan [8], who have used IEEE 802.11b access point signals to detect the location of a user....
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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
"Location determination of a mobile ..." refers methods in this paper
...The Cricket location-support system [6] uses a combination of RF and ultrasound....
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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
"Location determination of a mobile ..." refers background in this paper
...[4], [5] give a summary of the advancement in location tracking systems....
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