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RF sensor networks for device-free localization: Measurements, models and algorithms
- Proceedings of the IEEE
, 2010
"... Abstract—We discuss the emerging application of device-free localization using wireless sensor networks, which find people and objects in the environment in which the network is deployed, even in buildings and through walls. These networks are termed “RF sensor networks ” because the wireless networ ..."
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Cited by 33 (7 self)
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Abstract—We discuss the emerging application of device-free localization using wireless sensor networks, which find people and objects in the environment in which the network is deployed, even in buildings and through walls. These networks are termed “RF sensor networks ” because the wireless network itself is the sensor, using RF signals to probe the deployment area. Devicefree localization in cluttered multipath environments has been shown to be feasible, and in fact benefits from rich multipath channels. We describe modalities of measurements made by RF sensors, the statistical models which relate a person’s position to channel measurements, and describe research progress in this area. I.
Radio tomographic imaging for ambient assisted living
- in Evaluating AAL Systems Through Competitive Benchmarking, ser. Communications in Computer and Information
"... Abstract. Accurate localization of people in indoor and domestic en-vironments is one of the key requirements for ambient assisted living (AAL) systems. This chapter describes how the received signal strength (RSS) measurements collected by a network of static radio transceivers can be used to local ..."
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Cited by 14 (11 self)
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Abstract. Accurate localization of people in indoor and domestic en-vironments is one of the key requirements for ambient assisted living (AAL) systems. This chapter describes how the received signal strength (RSS) measurements collected by a network of static radio transceivers can be used to localize people without requiring them to wear or carry any radio device. We describe a technique named radio tomographic imaging (RTI), which produces real-time images of the change in the radio propagation field of the monitored area caused by the presence of people. People’s locations are inferred from the estimated RTI images. We show results from a long-term deployment in a typical single floor, one bedroom apartment. In order to deal with the dynamic nature of the domestic environment, we introduce methods to make the RTI system self-calibrating. Experimental results show that the average localization error of the system is 0.23 m. Moreover, the system is capable of adapt-ing to the changes in the indoor environment, achieving high localization accuracy over an extended period of time.
1 Through-Wall Motion Tracking Using Variance-Based Radio Tomography Networks
, 909
"... Abstract — This paper presents a new method for imaging, localizing, and tracking motion behind walls in real-time. The method takes advantage of the motion-induced variance of received signal strength measurements made in a wireless peerto-peer network. Using a multipath channel model, we show that ..."
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Cited by 13 (3 self)
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Abstract — This paper presents a new method for imaging, localizing, and tracking motion behind walls in real-time. The method takes advantage of the motion-induced variance of received signal strength measurements made in a wireless peerto-peer network. Using a multipath channel model, we show that the signal strength on a wireless link is largely dependent on the power contained in multipath components that travel through space containing moving objects. A statistical model relating variance to spatial locations of movement is presented and used as a framework for the estimation of a motion image. From the motion image, the Kalman filter is applied to recursively track the coordinates of a moving target. Experimental results for a 34-node through-wall imaging and tracking system over a 780 square foot area are presented. I.
Toward a Rapidly Deployable RTI System for Tactical Operations
"... Abstract—The ability for special operations forces (SOF) to rapidly deploy a through-building tracking system upon arrival at a tactical operation, e.g. a hostage scenario, and thereby estimate the approximate locations of the people within the building has the potential to lower the risk of the ope ..."
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Cited by 6 (6 self)
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Abstract—The ability for special operations forces (SOF) to rapidly deploy a through-building tracking system upon arrival at a tactical operation, e.g. a hostage scenario, and thereby estimate the approximate locations of the people within the building has the potential to lower the risk of the operation and save lives. We study the feasibility of a rapidly deployed radio frequency (RF)-based tomographic imaging (RTI) system for use in tactical operations by Special Weapons and Tactics (SWAT) and other SOF, in which several low-power radio devices are placed around a building and used to image and track the motion of humans inside the building. Specifically, we identify and study the constraints of this application, such as the need for the sensor network to self-localize and self-calibrate with minimal input from the SOF. We implement and test, in a wide variety of experimental deployments, a real-time RTI tracking system which adheres to these constraints and provides valuable situational intelligence. We work in concert with local law enforcement and SWAT in order to obtain valuable feedback from end users. We show that our system is capable of providing useful tracking information (average errors of less than two meters) even when the self-localization results are inaccurate (up to three meters average error). I.
Multi-sensor ATTenuation Estimation (MATTE): Signal-strength
"... prediction for teams of robots ..."
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DEMO ABSTRACT: REAL-TIME TAG-FREE LOCALIZATION USING RADIO TOMORAPHY
"... We propose to demonstrate real-time tag-free localization using radio tomography. In this demo abstract, we show the need for radio tomography, the models used, and some sample results. We discuss the needs and operation of the proposed demonstration. ..."
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We propose to demonstrate real-time tag-free localization using radio tomography. In this demo abstract, we show the need for radio tomography, the models used, and some sample results. We discuss the needs and operation of the proposed demonstration.
Date Approved
, 2010
"... Device-free localization (DFL) is the practice of locating people or objects when no tag or device is attached to the entity being tracked. DFL technologies are useful in applications where the targets being tracked and detected are not expected to cooperate with the system. This may be the case bec ..."
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Device-free localization (DFL) is the practice of locating people or objects when no tag or device is attached to the entity being tracked. DFL technologies are useful in applications where the targets being tracked and detected are not expected to cooperate with the system. This may be the case because the entities being tracked are evading surveillance, because they are unable, or because they do not want to be inconvenienced. This dissertation discusses some novel and cost-effective methods for locating people with received signal strength (RSS) measurements in wireless networks. The first contribution of this work presents a linear model for using received signal strength (RSS) measurements to obtain images of moving objects, a process called radio tomographic imaging (RTI). Noise models are investigated based on real measurements of a deployed RTI system. Mean-squared error (MSE) bounds on image accuracy are derived, which are used to calculate the accuracy of an RTI system for a given node geometry. The ill-posedness of RTI is discussed, and Tikhonov regularization is used to derive an image estimator.
1 Passive RFID Tomographic Imaging for Device-Free User Localization
"... Abstract – Localization of users is an important part of location aware systems and smart environments. It forms a major data source for superimposed intention recognition systems. In RF device-free localization (DFL), the person being tracked does not need to wear a RF transmitter or receiver in or ..."
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Abstract – Localization of users is an important part of location aware systems and smart environments. It forms a major data source for superimposed intention recognition systems. In RF device-free localization (DFL), the person being tracked does not need to wear a RF transmitter or receiver in order to be located. Instead, they are tracked using the changes in signal strength measured on static links in a wireless network. This work presents a new algorithm for RF DFL using passive RFID networks. We formulate and show how a tomographic imaging algorithm provides both low computational complexity and highly accurate position estimates. Using measurements conducted in an indoor environment with various human positions, we find the algorithm can locate the human with as low as 30 cm mean location error.
