CiteULike: mikkelbk's library [126 articles]

Location privacy in pervasive computing

AR Beresford — 2006-10-06T17:39:05-00:00

Pervasive Computing, IEEE, Vol. 2, No. 1. (2003), pp. 46-55.

As location-aware applications begin to track our movements in the name of convenience, how can we protect our privacy? This article introduces the mix zone-a new construction inspired by anonymous communication techniques-together with metrics for assessing user anonymity. It is based on frequently changing pseudonyms.

Deployment, Calibration, and Measurement Factors for Position Errors in 802.11-Based Indoor Positioning Systems

Thomas King — 2008-03-14T12:20:32-00:00

Location- and Context-Awareness (2007), pp. 17-34.

Indoor positioning systems based on 802.11 and fingerprints offer reasonably low position errors. We study the deployment, calibration, and measurement factors for position errors by systematically investigating (1) the number of access points, (2) the number of samples in the training phase, (3) the number of samples in the position determination phase, and (4) the setup of the grid of reference points. Further, we bring out the best of the positioning system by selecting advantageous values for these parameters. For our study, we utilize a test environment with a size of about 312 square meters that is covered with 612 reference points arranged in an equally spaced grid.

Overhearing the Wireless Interface for 802.11-Based Positioning Systems

Thomas King — 2008-02-26T19:33:10-00:00

Pervasive Computing and Communications, 2007. PerCom '07. Fifth Annual IEEE International Conference on (2007), pp. 145-150.

Not only the communication capabilities of 802.11, but also the capability to determine the position of mobile devices make 802.11 highly appealing for many application areas. Typically, a mobile device that wants to identify its position regularly performs active or passive scans to obtain the signal strength measurements of neighboring access points. However, so far, no investigations are known to have been launched into how regular scanning affects concurrent data transmissions from an end-user point of view. In this paper, we explore how common data communication is affected while actively or passively scanning at the same time. Furthermore, we present a novel scan scheme called monitor sniffing. Monitor sniffing exploits the fact that 802.11 operates on overlapping channels by overhearing the wireless interface. We have implemented our monitor sniffing algorithm using commodity 802.11g hardware, and we demonstrate that it does not disturb concurrent data communication

GETA sandals: a footstep location tracking system

Yeh — 2007-11-14T13:19:03-00:00

Personal and Ubiquitous Computing, Vol. 11, No. 6. (August 2007), pp. 451-463.

Analysing fundamental properties of marker-based vision system designs

Andrew Rice — 2007-03-14T04:13:31-00:00

Pervasive and Mobile Computing, Vol. 2, No. 4. (November 2006), pp. 453-471.

This paper investigates fundamental properties of marker-based vision (MBV) systems. We present a theoretical analysis of the performance of basic tag designs which is extended through simulation to investigate the effects of different processing algorithms. Real-world data are processed and related to the simulated results. Image processing is performed using Cantag, an open-source software toolkit for building marker-based vision (MBV) systems that can identify and accurately locate printed markers in three dimensions. Cantag supports multiple fiducial shapes, payload types, data sizes and image processing algorithms in one framework. This paper explores the design space of tags within the Cantag system, and describes the design parameters and performance characteristics which an application writer can use to select the best tag system for any given scenario.

VOR base stations for indoor 802.11 positioning

Drago\cs Niculescu — 2008-02-25T20:41:00-00:00

(2004), pp. 58-69.

Mobility Detection Using Everyday GSM Traces

Timothy Sohn — 2007-11-30T14:09:04-00:00

UbiComp 2006: Ubiquitous Computing (2006), pp. 212-224.

Recognition of everyday physical activities is difficult due to the challenges of building informative, yet unobtrusive sensors. The most widely deployed and used mobile computing device today is the mobile phone, which presents an obvious candidate for recognizing activities. This paper explores how coarse-grained GSM data from mobile phones can be used to recognize high-level properties of user mobility, and daily step count. We demonstrate that even without knowledge of observed cell tower locations, we can recognize mobility modes that are useful for several application domains. Our mobility detection system was evaluated with GSM traces from the everyday lives of three data collectors over a period of one month, yielding an overall average accuracy of 85%, and a daily step count number that reasonably approximates the numbers determined by several commercial pedometers.

Pervasive Computing and Autism: Assisting Caregivers of Children with Special Needs

Julie Kientz — 2007-11-30T13:04:35-00:00

Pervasive Computing, IEEE, Vol. 6, No. 1. (2007), pp. 28-35.

Pervasive computing technologies can support children with autism and their caregivers. Work continues on systems that aid record collection and analysis, decision making, communication, and assessment of children's internal states

Seamful interweaving: heterogeneity in the theory and design of interactive systems

Matthew Chalmers — 2005-08-11T10:57:59-00:00

(2004), pp. 243-252.

Workers' Routine Activity Recognition using Body Movements and Location Information

Futoshi Naya — 2007-10-12T09:24:37-00:00

Wearable Computers, 2006 10th IEEE International Symposium on (2006), pp. 105-108.

We propose a method for recognizing workers' routine activities by combining location information and body movements of a user. We describe methods for capturing and recognizing the nursing context with an Infrared-ID location sensor system and accelerometers worn by a user. We show experimental results of recognizing typical activities in a nursing scenario in a laboratory setting.

A Practical Approach to Recognizing Physical Activities

Jonathan Lester — 2006-12-16T07:27:19-00:00

Lecture Notes in Computer Science : Pervasive Computing (2006), pp. 1-16.

iCam: Precise at-a-Distance Interaction in the Physical Environment

Shwetak Patel — 2007-03-17T06:08:03-00:00

: Pervasive Computing (2006), pp. 272-287.

Cleaning and Processing RSS Measurements for Location Fingerprinting

Mikkel Kjaergaard — 2007-10-02T11:55:37-00:00

(2007)

A Taxonomy for Radio Location Fingerprinting

Mikkel Kjærgaard — 2007-10-02T11:36:54-00:00

Location- and Context-Awareness (2007), pp. 139-156.

Location Fingerprinting (LF) is a promising location technique for many awareness applications in pervasive computing. However, as research on LF systems goes beyond basic methods there is an increasing need for better comparison of proposed LF systems. Developers of LF systems are also lacking good frameworks for understanding different options when building LF systems. This paper proposes a taxonomy to address both of these problems. The proposed taxonomy has been constructed from a literature study of 51 papers and articles about LF. For researchers the taxonomy can also be used as an aid when scoping out future research in the area of LF.

Implementing a sentient computing system

M Addlesee — 2007-10-02T11:35:32-00:00

Computer, Vol. 34, No. 8. (2001), pp. 50-56.

Sentient computing systems, which can change their behaviour based on a model of the environment they construct using sensor data, may hold the key to managing tomorrow's device-rich mobile networks. At AT&T Laboratories Cambridge, we have built a system that uses sensors to update a model of the real world. We designed the model's terms (object positions, descriptions and state, and so forth) to be immediately familiar to users. Thus, the model describes the world much as users themselves would. We can use this model to write programs that react to changes in the environment according to the user's preferences. We call this sentient computing because the applications appear to share the user's perception of the environment. Treating the current state of the environment as common ground between computers and users provides new ways of interacting with information systems. A sentient computing system doesn't need to be intelligent or capable of forming new concepts about the world, it only needs to act as though its perceptions duplicate the user's. In earlier work, we described a prototype of this system and stated our intention to deploy it on a large scale. We have now installed an enhanced version throughout an office building. Over the past year, approximately 50 staff members have used the system daily with a set of trial applications

A new location technique for the active office

A Ward — 2005-10-12T09:29:42-00:00

Personal Communications, IEEE [see also IEEE Wireless Communications], Vol. 4, No. 5. (1997), pp. 42-47.

Configuration of the computing and communications systems found at home and in the workplace is a complex task that currently requires the attention of the user. Researchers have begun to examine computers that would autonomously change their functionality based on observations of who or what was around them. By determining their context, using input from sensor systems distributed throughout the environment, computing devices could personalize themselves to their current user, adapt their behaviour according to their location, or react to their surroundings. The authors present a novel sensor system, suitable for large-scale deployment in indoor environments, which allows the locations of people and equipment to be accurately determined. We also describe some of the context-aware applications that might make use of this fine-grained location information

Deploying and evaluating a location-aware system

RK Harle — 2007-09-09T11:19:39-00:00

(2005), pp. 219-232.

Experiences from Real-World Deployment of Context-Aware Technologies in a Hospital Environment

Jakob Bardram — 2007-03-08T15:06:59-00:00

: UbiComp 2006: Ubiquitous Computing (2006), pp. 369-386.

Can you see me now?

Steve Benford — 2006-10-08T14:05:54-00:00

ACM Trans. Comput.-Hum. Interact., Vol. 13, No. 1. (March 2006), pp. 100-133.

Hitchers: Designing for Cellular Positioning

Adam Drozd — 2007-09-08T19:58:15-00:00

UbiComp 2006: Ubiquitous Computing (2006), pp. 279-296.

Hitchers is a game for mobile phones that exploits cellular positioning to support location-based play. Players create digital hitch hikers, giving them names, destinations and questions to ask other players, and then drop them into their current phone cell. Players then search their current cell for hitchers, pick them up, answer their questions, carry them to new locations and drop them again, providing location-labels as hint to where they can be found. In this way, hitchers pass from player to player, phone to phone and cell to cell, gathering information and encouraging players to label cells with meaningful place names. A formative study of Hitchers played by 47 players over 4 months shows how the seams in cellular positioning, including varying cell size, density and overlap, affected the experience. Building on previous discussions of designing for uncertainty and seamful design, we consider five ways of dealing with these seams: removing, hiding, managing, revealing and exploiting them. This leads us to propose the mechanism of a dynamic search focus, to explore new visualization tools for cellular data, and to reconsider the general relationship between ‘virtual’ and ‘physical’ worlds in location-based games. Keywords: Mobile games, cellular positioning, ubiquitous computing, seamful design.

The spatial character of sensor technology

Stuart Reeves — 2006-10-08T14:53:28-00:00

(2006), pp. 31-40.

A sensor network for social dynamics

M Laibowitz — 2007-09-07T12:19:48-00:00

Information Processing in Sensor Networks, 2006. IPSN 2006. The Fifth International Conference on (2006), pp. 483-491.

This paper describes the design and architecture of the UbER-Badge, a wireless sensor node and wearable display designed to facilitate group interaction in large meetings and acquire a wide range of data for analyzing social dynamics. The platform design and its application suite are described. Data is presented that shows the social patterns developing across large events and indicates that certain individual characteristics (interest, affiliation) can be determined from the sensor data from deployments of this system with groups of over 100 people.

Mapping human networks

J Gips — 2007-09-07T12:18:51-00:00

Pervasive Computing and Communications, 2006. PerCom 2006. Fourth Annual IEEE International Conference on (2006), 10 pp..

We have developed a method of measuring user interest and affiliation for conference attendees, using behavioral data to collected by 'smart badges' worn by the attendees. These measures allow validation, refinement, and extension of online user profiles, improving the dissemination of conference information.

IntelliBadge : Towards Providing Location-Aware Value-Added Services at Academic Conferences

Donna Cox — 2007-09-07T12:17:43-00:00

UbiComp 2003: Ubiquitous Computing (2003), pp. 264-280.

This paper contains details on a project aimed to provide location-aware value- added services to the participants of an academic conference. The major characteristic of this project is the fusion of RFID technology, database management, data mining, real-time information visualization, and interactive web application technologies into an operational integrated system deployed at a major public conference. The developed system tracks conference attendees, analyzes the tracking data in real-time and provides various services to the attendees, such as a real-time snapshot of the conference events attendance, the ability to locate friends in the convention center, and the ability to search for events of interest. The results of this experiment were revealing in terms of both the potential of the developed technology and the conference dynamics.

Designing a positioning system for finding things and people indoors

J Werb — 2007-09-07T12:15:48-00:00

Spectrum, IEEE, Vol. 35, No. 9. (1998), pp. 71-78.

Despite extraordinary advances in Global Positioning System (GPS) technology, millions of square meters of indoor space are out of reach of Navstar satellites. Their signals, originating high above the Earth, are not designed to penetrate most construction materials, and no amount of technical wizardry is likely to help. So the greater part of the world's commerce, being conducted indoors, cannot be followed by GPS satellites. Here, the authors describe how tracking people and assets indoors has now moved from the realm of science fiction to reality, thanks to a radiofrequency identification technique now being introduced to the market

Active badges and personal interactive computing objects

R Want — 2006-09-30T23:15:25-00:00

Consumer Electronics, IEEE Transactions on, Vol. 38, No. 1. (1992), pp. 10-20.

The authors describe a family of personal active badges developed for location of people and devices in the computer environment. Applications include location and paging of individuals as well as control of computer systems. Active badges are one type of a range of portable computers connected to cordless communication systems that can now be made. Because of their small size and application such devices are referred to as personal interactive computing objects. A speculative discussion of how such devices may be used in the traditional computing environment is given

A distributed location system for the active office

A Harter — 2007-09-07T12:04:12-00:00

Network, IEEE, Vol. 8, No. 1. (1994), pp. 62-70.

Distributed systems for locating people and equipment will be at the heart of tomorrow's active offices. Computer and communications systems continue to proliferate in the office and home. Systems are varied and complex, involving wireless networks and mobile computers. However, systems are underused because the choices of control mechanisms and application interfaces are too diverse. It is therefore pertinent to consider which mechanisms might allow the user to manipulate systems in simple and ubiquitous ways, and how computers can be made more aware of the facilities in their surroundings. Knowledge of the location of people and equipment within an organization is such a mechanism. Annotating a resource database with location information allows location-based heuristics for control and interaction to be constructed. This approach is particularly attractive because location techniques can be devised that are physically unobtrusive and do not rely on explicit user action. The article describes the technology of a system for locating people and equipment, and the design of a distributed system service supporting access to that information. The application interfaces made possible by or that benefit from this facility are presented

Smart tags-the distributed-memory revolution

P Hewkin — 2007-09-06T07:50:15-00:00

IEE Review, Vol. 35, No. 6. (1989), pp. 203-206.

`Smart tags' are small devices containing a combination of memory, data processing and communications capabilities. They can communicate without physical contact with purpose-specific stations over a range from a few millimetres up to several metres. Their shapes and sizes are application specific, ranging from the size of a brick right down to a capsule of a few millimetres diameter. The author discusses the technology used in smart tags which are either active or passive depending on whether or not they incorporate a miniature battery. The author then discusses some of the applications for smart tags such as car-body identification in automobile manufacture, personnel security, animal identification, manufacturing and goods transportation

Zone-Based RSS Reporting for Location Fingerprinting

Mikkel Kjærgaard — 2007-08-28T21:09:50-00:00

Pervasive Computing (2007), pp. 316-333.

In typical location fingerprinting systems a tracked terminal reports sampled Received Signal Strength (RSS) values to a location server, which estimates its position based on a database of pre-recorded RSS fingerprints. So far, poll-based and periodic RSS reporting has been proposed. However, for supporting proactive Location-based Services (LBSs), triggered by pre-defined spatial events, the periodic protocol is inefficient. Hence, this paper introduces zone-based RSS reporting: the location server translates geographical zones defined by the LBS into RSS-based representations, which are dynamically configured with the terminal. The terminal, in turn, reports its measurements only when they match with the configured RSS patterns. As a result, the number of messages exchanged between terminal and server is strongly reduced, saving battery power, bandwidth and also monetary costs spent for mobile bearer services. The paper explores several methods for realizing zone-based RSS reporting and evaluates them simulatively and analytically. An adaption of classical Bayes estimation turns out to be the best suited method.

PowerLine Positioning: A Practical Sub-Room-Level Indoor Location System for Domestic Use

Shwetak Patel — 2007-08-01T07:58:11-00:00

UbiComp 2006: Ubiquitous Computing (2006), pp. 441-458.

Using existing communications infrastructure, such as 802.11 and GSM, researchers have demonstrated effective indoor localization. Inspired by these previous approaches, and recognizing some limitations of relying on infrastructure users do not control, we present an indoor location system that uses an even more ubiquitous domestic infrastructure—the residential powerline. PowerLine Positioning (PLP) is an inexpensive technique that uses fingerprinting of multiple tones transmitted along the powerline to achieve sub-room-level localization. We describe the basics behind PLP and demonstrate how it compares favorably to other fingerprinting techniques.

Wiki for Location Fingerprinting Taxonomy

2007-07-30T18:12:53-00:00

Power-efficient access-point selection for indoor location estimation

Yiqiang Chen — 2007-07-27T21:01:54-00:00

Knowledge and Data Engineering, IEEE Transactions on, Vol. 18, No. 7. (2006), pp. 877-888.

An important goal of indoor location estimation systems is to increase the estimation accuracy while reducing the power consumption. In this paper, we present a novel algorithm known as CaDet for power-efficient location estimation by intelligently selecting the number of access points (APs) used for location estimation. We show that by employing machine learning techniques, CaDet is able to use a small subset of the APs in the environment to detect a client's location with high accuracy. CaDet uses a combination of information theory, clustering analysis, and a decision tree algorithm. By collecting data and testing our algorithms in a realistic WLAN environment in the computer science department area of the Hong Kong University of Science and Technology, we show that CaDet (clustering and decision tree-based method) can be much higher in accuracy as compared to other methods. We also show through experiments that, by intelligently selecting APs, we are able to save the power on the client device while achieving the same level of accuracy.

Analysis of a signal strength based positioning system for commercial environments

MJ Johnson — 2007-07-17T19:34:22-00:00

Consumer Communications and Networking Conference, 2005. CCNC. 2005 Second IEEE (2005), pp. 533-538.

Signal strength based positioning technology offers both cost advantages and technical challenges compared with other positioning methods. This study analyzes measurements taken in a commercial retail environment to develop a set of practical expectations and guidelines in the use of signal strength based positioning systems. A commercially available positioning engine for wireless LANs was used as a readily reproducible basis for the experiments.

An adaptive two-phase approach to WiFi location sensing

Wenyao Ho — 2007-07-09T04:44:02-00:00

Pervasive Computing and Communications Workshops, 2006. PerCom Workshops 2006. Fourth Annual IEEE International Conference on (2006), 5 pp..

Environmental variations cause significant fluctuations in WiFi signals in the same location over time, rendering traditional RF-to-location pre-trained maps quickly obsolete. To solve this problem, we use a two-phase approach to determining the user's location. The first phase utilizes traditional pattern-matching to identify the general location, and a second phase applies logistic regression to distinguish between finer-grained locations. An adaptive calibration system allows the user to re-train and dynamically update the signal strength maps to account for the fluctuated signals. We show that our two-phase approach is able to achieve generally high accuracy (-95%) and over in areas of high signal fluctuations due to heavy access point and human density.

Adaptive Temporal Radio Maps for Indoor Location Estimation

Jie Yin — 2007-07-08T21:07:55-00:00

Pervasive Computing and Communications, 2005. PerCom 2005. Third IEEE International Conference on (2005), pp. 85-94.

In this paper, we present a novel method to adapt the temporal radio maps for indoor location estimation by off-setting the variational environmental factors using data mining techniques and reference points. Environmental variations, which cause the signals to change from time to time even at the same location, present a challenging task for indoor location estimation in the IEEE 802.11b infrastructure. In such a dynamic environment, the radio maps obtained in one time period may not be applicable in other time periods. To solve this problem, we apply a regression analysis to learn the temporal predictive relationship between the signal-strength values received by sparsely located reference points and that received by the mobile device. This temporal prediction model can then be used for online localization based on the newly observed signal-strength values at the client side and the reference points. We show that this technique can effectively accommodate the variations of signal-strength values over different time periods without the need to rebuild the radio maps repeatedly. We also show that the location of mobile device can be accurately determined using this technique with lower density in the distribution of the reference points.

Radio map fusion for indoor positioning in wireless local area networks

A Kushki — 2007-07-08T20:08:35-00:00

Information Fusion, 2005 8th International Conference on, Vol. 2 (2005), 8 pp..

This paper addresses the problem of indoor location estimation (LE) in wireless local area network (WLAN) using received signal strength (RSS). The difficultly of the problem lies in the complexity of the indoor propagation channel at operating WLAN frequency of 2.4 GHz, resulting in nonlinear and non-Gaussian spatio-temporal RSS properties. The first contribution of this paper is the introduction of a non-parametric Nadaraya-Watson estimator for LE using location fingerprints to capture the spatial distribution of RSS. Secondly, a novel method is proposed based on fusion of multiple location fingerprints at each survey location to cope with multimodal temporal probability distributions of RSS. Experimental results using real data collected in an office environment indicate that the proposed multiple-map method outperforms the KNN-based LE methods in terms of root mean square error.

Location Tracking in Wireless Local Area Networks with Adaptive Radio MAPS

A Kushki — 2007-07-08T20:08:07-00:00

Acoustics, Speech and Signal Processing, 2006. ICASSP 2006 Proceedings. 2006 IEEE International Conference on, Vol. 5 (2006), pp. V-V.

This paper proposes a dynamic MMSE estimator for tracking mobile users in indoor wireless local area networks (WLAN) based on received signal strength (RSS). The method uses a training-based static estimate obtained by an adaptive kernel density estimator as the input into a Kalman Filter. Predictions from the filter are used during the next iteration to adaptively select a subset of training data, contained in a radio map, for the static estimator. Experimental results show that the combination of the Kalman filter and the adaptive radio map technique results in nearly 0.5 m (20%) improvement in root mean square location accuracy when compared to static localization

Kernel-Based Positioning in Wireless Local Area Networks

Azadeh Kushki — 2007-07-08T20:07:17-00:00

Mobile Computing, IEEE Transactions on, Vol. 6, No. 6. (2007), pp. 689-705.

The recent proliferation of location-based services (LBSs) has necessitated the development of effective indoor positioning solutions. In such a context, wireless local area network (WLAN) positioning is a particularly viable solution in terms of hardware and installation costs due to the ubiquity of WLAN infrastructures. This paper examines three aspects of the problem of indoor WLAN positioning using received signal strength (RSS). First, we show that, due to the variability of RSS features over space, a spatially localized positioning method leads to improved positioning results. Second, we explore the problem of access point (AP) selection for positioning and demonstrate the need for further research in this area. Third, we present a kernelized distance calculation algorithm for comparing RSS observations to RSS training records. Experimental results indicate that the proposed system leads to a 17 percent (0.56 m) improvement over the widely used K-nearest neighbor and histogram-based methods

Location-Based Information Delivery Using Stream Processing Engine

S Yamada — 2007-06-13T08:06:34-00:00

Mobile Data Management, 2006. MDM 2006. 7th International Conference on (2006), pp. 57-57.

Recent developments in network and sensor device technologies enable us to easily obtain real-world information, such as locations of moving objects and environment information including brightness and temperature. These data are continuously supplied as they change over time, and they are regarded as data streams. The requirements for online processing of such data streams are increasing. In this demonstration, we present location-based information delivery using StreamSpinner, our stream processing engine. StreamSpinner achieves efficient stream data processing based on novel multiple continuous query optimization techniques. Using the StreamSpinner API, we built a location-based information delivery system for exhibition visitors. Locations of exhibition visitors are continuously monitored and supplied as data streams. Useful information about nearby exhibits and the availability of exhibition hall facilities is provided by the system to visitor terminals. Online integration of streams and database contents is achieved in the demonstration system.

The theory and practice of signal strength-based location estimation

AS Krishnakumar — 2007-05-23T10:20:29-00:00

Collaborative Computing: Networking, Applications and Worksharing, 2005 International Conference on (2005), 10 pp..

Location estimation enables many innovative applications and is an exciting area of research. With the growing use of wireless technology in enterprise networks, it is an interesting technical challenge to develop techniques for indoor location estimation that leverage the deployed wireless infrastructure. Elegant, cost-effective techniques would present a compelling business proposition. In this paper, we summarize various approaches researchers have studied for the problem of indoor location estimation, concentrating on signal-strength based techniques directed towards 802.11 wireless networks. We also summarize an interesting insight into the best possible accuracy achievable by any technique due to limits imposed by the physical behavior of the radio signal. We identify that the issues driving research work in this area will not only be location accuracy, but other factors like deployment ease, management simplicity, adaptability, and cost of ownership and maintenance. We conclude with some open research problems in this area.

MoteTrack: a robust, decentralized approach to RF-based location tracking

Konrad Lorincz — 2007-05-10T09:37:13-00:00

Personal and Ubiquitous Computing

MoteTrack: A Robust, Decentralized Approach to RF-Based Location Tracking.

Konrad Lorincz — 2007-05-10T09:34:47-00:00

Vol. 3479 (2005), pp. 63-82.

Using wireless Ethernet for localization

AM Ladd — 2007-04-25T12:00:10-00:00

Intelligent Robots and System, 2002. IEEE/RSJ International Conference on, Vol. 1 (2002), pp. 402-408 vol.1.

IEEE 802.11b wireless Ethernet is rapidly becoming the standard for in-building and short-range wireless communication. Many mobile devices such as mobile robots, laptops and PDAs already use this protocol for wireless communication. Many wireless Ethernet cards measure the signal strength of incoming packets. This paper investigates the feasibility of implementing a localization system using this sensor. Using a Bayesian localization framework, we show experiments demonstrating that off-the-shelf wireless hardware can accurately be used for location sensing and tracking with about one meter precision in a wireless-enabled office building.

On the Feasibility of Using Wireless Ethernet for Indoor Localization

A Ladd — 2007-04-25T11:56:18-00:00

IEEE802.11b wireless Ethernet isbu19803 the standard for indoor wireless communication. This paper proposes the use of measured signal strength of Ethernet packets as a sensor for a localization system. We demonstrate that off-the-shelf hardware can accuratelyb used for location sensing and real-time trackingb applying a Bayesian localization framework.

Reducing the Calibration Effort for Location Estimation Using Unlabeled Samples

Xiaoyong Chai — 2007-04-25T08:14:30-00:00

Pervasive Computing and Communications, 2005. PerCom 2005. Third IEEE International Conference on (2005), pp. 95-104.

WLAN location estimation based on 802.11 signal strength is becoming increasingly prevalent in today’s pervasive computing applications. As an alternative to the well-established deterministic approaches, probabilistic location determination techniques show good performance and thus become increasingly popular. For these techniques to achieve a high level of accuracy, however, adequate training samples should be collected offline for calibration. As a result, a great amount of manual effort is incurred. In this paper, we aim to solve the problem by reducing both the sampling time and the number of locations sampled in constructing the radio map. A learning algorithm is proposed to build location estimation systems based on a small fraction of the calibration data that traditional techniques require and a collection of user traces that can be cheaply obtained. Our experiments show that unlabeled user traces can be used to compensate for the effects of reducing calibration effort and can even improve the system performance. Consequently, manual effort can be significantly reduced while a high level of accuracy is still achieved.

Robust location using system dynamics and motion constraints

C Gentile — 2007-04-25T07:42:47-00:00

Communications, 2004 IEEE International Conference on, Vol. 3 (2004), pp. 1360-1364 Vol.3.

To our knowledge, the indoor location system which currently achieves the best performance using inexpensive off-the-shelf equipment locates a mobile within 1.5 meters with probability 77% in hallways. Even while maintaining this accuracy, the system often reports logical errors such as the mobile in the wrong cubicle of an office or even on the wrong side of a wall when broadening the domain of application to within rooms. We propose an extension of the work using the same Markov localization framework, however incorporating system dynamics (necessitating no post-processing of the output) and motion constraints which implicitly encode the physical properties of the survey area. Our system retains the advantages of its predecessor of low cost, wireless LAN connectivity and security, and large-scale deployment, however extending the survey area from simple hallways to the whole office environment, while maintaining the same precision without logical errors.

Markov Localization of Wireless Local Area Network Clients.

Michael Wallbaum — 2007-04-24T09:04:39-00:00

Vol. 2928 (2004), pp. 1-15.

Indoor Positioning UsingWireless Local Area Networks

M Wallbaum — 2007-04-24T09:00:35-00:00

Modern Computing, 2006. JVA '06. IEEE John Vincent Atanasoff 2006 International Symposium on (2006), pp. 17-26.

Determining the context of users and machines is an important topic in current computing research. An essential detail of a physical object's context is its location, which includes both the actual position as well as the semantics of the surroundings. This paper focuses on the specific problem of determining the position of objects and people within buildings. A low-cost approach is based on wireless LANs, which are now widely deployed. The paper presents a sophisticated probabilistic algorithm for indoor positioning using wireless LANs, but also discusses the problems that need to be solved to make indoor geolocation commonplace

WhereMoPS: an indoor geolocation system

M Wallbaum — 2007-04-24T08:54:12-00:00

Personal, Indoor and Mobile Radio Communications, 2002. The 13th IEEE International Symposium on, Vol. 4 (2002), pp. 1967-1971 vol.4.

Locating users and terminals accurately within buildings is an important technology for mobile applications. However indoor geolocation systems presented in the past are often restricted to certain applications or sensor systems and mostly provide location information in a context-specific manner. The WhereMoPS system is a flexible research platform for advanced indoor geolocation systems which can be extended to integrate additional sensing subsystems and positioning algorithms. The location information is distributed by means of the Mobile Positioning Protocol (MPP) originally designed for location-based services in GSM networks. This paper describes the WhereMoPS system design and implementation as well as the modifications necessary to adapt MPP to indoor environments.

Bayesian indoor positioning systems

D Madigan — 2006-11-02T21:22:03-00:00

INFOCOM 2005. 24th Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings IEEE, Vol. 2 (2005), pp. 1217-1227 vol. 2.

In this paper, we introduce a new approach to location estimation where, instead of locating a single client, we simultaneously locate a set of wireless clients. We present a Bayesian hierarchical model for indoor location estimation in wireless networks. We demonstrate that our model achieves accuracy that is similar to other published models and algorithms. By harnessing prior knowledge, our model eliminates the requirement for training data as compared with existing approaches, thereby introducing the notion of a fully adaptive zero profiling approach to location estimation.