Abstract Self-configuration in wireless sensor networks is a general class of estimation problems... more Abstract Self-configuration in wireless sensor networks is a general class of estimation problems that we study via the Cramer-Rao bound (CRB). Specifically, we consider sensor location estimation when sensors measure received signal strength (RSS) or time-of-arrival (TOA) between themselves and neighboring sensors. A small fraction of sensors in the network have a known location, whereas the remaining locations must be estimated.
Abstract In this paper, we discuss the emerging application of device-free localization (DFL) usi... more Abstract In this paper, we discuss the emerging application of device-free localization (DFL) 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 radio-frequency (RF) signals to probe the deployment area.
Abstract—Location distinction is defined as de-termining when a device has changed its position. ... more Abstract—Location distinction is defined as de-termining when a device has changed its position. Previous work [4],[8] has shown that a wireless network can be exploited to successfully perform location distinction by measuring the characteristics of the SISO radio channel between the wireless device and one or more receivers. We propose methods and metrics for MIMO-based location distinction.
Abstract Human motion in the vicinity of a wireless link causes variations in the link received s... more Abstract Human motion in the vicinity of a wireless link causes variations in the link received signal strength (RSS). Device-free localization (DFL) systems, such as variance-based radio tomographic imaging (VRTI) use these RSS variations in a wireless network to detect, locate and track people in the area of the network, even through walls. However, intrinsic motion, such as branches moving in the wind, rotating or vibrating machinery, also causes RSS variations which degrade the performance of a DFL system.
Abstract We propose an approach where wireless devices, interested in establishing a secret key, ... more Abstract We propose an approach where wireless devices, interested in establishing a secret key, sample the channel impulse response (CIR) space in a physical area to collect and combine uncorrelated CIR measurements to generate the secret key. We study the impact of mobility patterns in obtaining uncorrelated measurements.
Abstract Device-free localization (DFL) is the estimation of the position of a person or object t... more Abstract Device-free localization (DFL) is the estimation of the position of a person or object that does not carry any electronic device or tag. Existing model-based methods for DFL from RSS measurements are unable to locate stationary people in heavily obstructed environments. This paper introduces measurement-based statistical models that can be used to estimate the locations of both moving and stationary people using received signal strength (RSS) measurements in wireless networks.
One of the major developments in WWII was the miniaturization of FM radio components to a backpac... more One of the major developments in WWII was the miniaturization of FM radio components to a backpack or handheld device (the walkie-talkie), a half-duplex (either transmit or receive, not both) push-to-talk communication device. After returning from war, veterans had the expectation that wireless communications should be available in their civilian jobs [26]. But the phone system, the Public Switched Telephone Network (PSTN) was: wired, and manually switched at telephone exchanges.
Abstract Accurate and low-cost sensor localization is a critical requirement for the deployment o... more Abstract Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of applications. In cooperative localization, sensors work together in a peer-to-peer manner to make measurements and then forms a map of the network. Various application requirements influence the design of sensor localization systems.
Abstract Multistatic radar is used for target detection and tracking in buildings and rooms. Targ... more Abstract Multistatic radar is used for target detection and tracking in buildings and rooms. Target detection and tracking relies on accurate knowledge of the excess delay of the multipath component which travels from the transmitter, to the target, and then to the receiver. If the environment creates many multipath components, individual ultra-wideband (UWB) impulses overlap.
Abstract Perimeter distinction in a wireless network is the ability to distinguish locations belo... more Abstract Perimeter distinction in a wireless network is the ability to distinguish locations belonging to different perimeters. It is complementary to existing localization techniques. A draw-back of the localization method is that when a transmitter is at the edge of an area, an algorithm with isotropic error will estimate its location in the wrong area at least half of the time. In contrast, perimeter distinction classifies the location as being in one area or the adjacent regardless of the transmitter position within the area.
Abstract—Radio tomographic imaging (RTI) is an emerging device-free localization (DFL) technology... more Abstract—Radio tomographic imaging (RTI) is an emerging device-free localization (DFL) technology enabling the localization of people and other objects without requiring them to carry any electronic device. Instead, the RF attenuation field of the deployment area of a wireless network is estimated using the changes in received signal strength (RSS) measured on links of the network. This paper presents the use of channel diversity to improve the localization accuracy of RTI.
Abstract Tracking of people via active badges is important for location-aware computing and for s... more Abstract Tracking of people via active badges is important for location-aware computing and for security applications. However, the human body has a major effect on the antenna gain pattern of the device that the person is wearing. In this paper, the gain pattern due to the effect of the human body is experimentally measured and represented by a first-order directional gain pattern model. A method is presented to estimate the model parameters from multiple received signal strength (RSS) measurements.
Abstract A wireless network can use the variance of measured received signal strength (RSS) on th... more Abstract A wireless network can use the variance of measured received signal strength (RSS) on the links in a network to infer the locations of people or objects moving in the network deployment area. This paper provides a statistical model for the RSS variance as a function of a person's position with respect to the transmitter (TX) and receiver (RX) locations.
Abstract—Device-free localization (DFL) enables localizing people by monitoring the changes in th... more Abstract—Device-free localization (DFL) enables localizing people by monitoring the changes in the radio frequency (RF) attenuation field of an area where a wireless network is deployed. Notably, this technology does not require people to participate in the localization effort by carrying any electronic device. This paper presents a DFL system for long-term residential monitoring. Due to the daily activities carried out by the people being monitored, the radio signals' propagation patterns change continuously.
ABSTRACT We propose to demonstrate real-time tag-free localization using radio tomography. In thi... more ABSTRACT 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.
Abstract Localization of users is an important part of location aware systems and smart environme... more 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.
Abstract–Radio frequency (RF) sensor networks are wireless sensor networks (WSNs) which use only ... more Abstract–Radio frequency (RF) sensor networks are wireless sensor networks (WSNs) which use only the received signal strength (RSS) to perform tasks such as device-free localization (DFL) and tracking of individuals. In these systems, people to be located do not participate in the localization effort by carrying any radio device or sensor. Instead, a static deployed wireless network measures RSS on its links and locates people based on the variations caused by the movements of people in the monitored area.
Abstract In this work, we evaluate the use of multiple sensors for secret key extraction. We find... more Abstract In this work, we evaluate the use of multiple sensors for secret key extraction. We find that the key generation rate increases linearly with the number of nodes. We show that the use of multiple nodes causes a significant mismatch in the extracted bits. We address the high bit mismatch problem by adding an iterative distillation stage to the key extraction process.
The broadcast nature of wireless medium has long been viewed as a trouble maker that causes the r... more The broadcast nature of wireless medium has long been viewed as a trouble maker that causes the radio channel interference, packet collision, information leakage, etc, and makes wireless networks more difficult to use than their wired peers. Our research, however, uses the complex behavior of the wireless channel to improve wireless network services. Specifically, we propose to leverage wireless physical layer measurements for location distinction.
Abstract A radio channel-based location distinction system monitors physical layer measurements o... more Abstract A radio channel-based location distinction system monitors physical layer measurements of received signals to detect if a transmitter has changed position since its previous transmission. This paper explores the design space for MIMO-based location distinction systems.
Abstract Self-configuration in wireless sensor networks is a general class of estimation problems... more Abstract Self-configuration in wireless sensor networks is a general class of estimation problems that we study via the Cramer-Rao bound (CRB). Specifically, we consider sensor location estimation when sensors measure received signal strength (RSS) or time-of-arrival (TOA) between themselves and neighboring sensors. A small fraction of sensors in the network have a known location, whereas the remaining locations must be estimated.
Abstract In this paper, we discuss the emerging application of device-free localization (DFL) usi... more Abstract In this paper, we discuss the emerging application of device-free localization (DFL) 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 radio-frequency (RF) signals to probe the deployment area.
Abstract—Location distinction is defined as de-termining when a device has changed its position. ... more Abstract—Location distinction is defined as de-termining when a device has changed its position. Previous work [4],[8] has shown that a wireless network can be exploited to successfully perform location distinction by measuring the characteristics of the SISO radio channel between the wireless device and one or more receivers. We propose methods and metrics for MIMO-based location distinction.
Abstract Human motion in the vicinity of a wireless link causes variations in the link received s... more Abstract Human motion in the vicinity of a wireless link causes variations in the link received signal strength (RSS). Device-free localization (DFL) systems, such as variance-based radio tomographic imaging (VRTI) use these RSS variations in a wireless network to detect, locate and track people in the area of the network, even through walls. However, intrinsic motion, such as branches moving in the wind, rotating or vibrating machinery, also causes RSS variations which degrade the performance of a DFL system.
Abstract We propose an approach where wireless devices, interested in establishing a secret key, ... more Abstract We propose an approach where wireless devices, interested in establishing a secret key, sample the channel impulse response (CIR) space in a physical area to collect and combine uncorrelated CIR measurements to generate the secret key. We study the impact of mobility patterns in obtaining uncorrelated measurements.
Abstract Device-free localization (DFL) is the estimation of the position of a person or object t... more Abstract Device-free localization (DFL) is the estimation of the position of a person or object that does not carry any electronic device or tag. Existing model-based methods for DFL from RSS measurements are unable to locate stationary people in heavily obstructed environments. This paper introduces measurement-based statistical models that can be used to estimate the locations of both moving and stationary people using received signal strength (RSS) measurements in wireless networks.
One of the major developments in WWII was the miniaturization of FM radio components to a backpac... more One of the major developments in WWII was the miniaturization of FM radio components to a backpack or handheld device (the walkie-talkie), a half-duplex (either transmit or receive, not both) push-to-talk communication device. After returning from war, veterans had the expectation that wireless communications should be available in their civilian jobs [26]. But the phone system, the Public Switched Telephone Network (PSTN) was: wired, and manually switched at telephone exchanges.
Abstract Accurate and low-cost sensor localization is a critical requirement for the deployment o... more Abstract Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of applications. In cooperative localization, sensors work together in a peer-to-peer manner to make measurements and then forms a map of the network. Various application requirements influence the design of sensor localization systems.
Abstract Multistatic radar is used for target detection and tracking in buildings and rooms. Targ... more Abstract Multistatic radar is used for target detection and tracking in buildings and rooms. Target detection and tracking relies on accurate knowledge of the excess delay of the multipath component which travels from the transmitter, to the target, and then to the receiver. If the environment creates many multipath components, individual ultra-wideband (UWB) impulses overlap.
Abstract Perimeter distinction in a wireless network is the ability to distinguish locations belo... more Abstract Perimeter distinction in a wireless network is the ability to distinguish locations belonging to different perimeters. It is complementary to existing localization techniques. A draw-back of the localization method is that when a transmitter is at the edge of an area, an algorithm with isotropic error will estimate its location in the wrong area at least half of the time. In contrast, perimeter distinction classifies the location as being in one area or the adjacent regardless of the transmitter position within the area.
Abstract—Radio tomographic imaging (RTI) is an emerging device-free localization (DFL) technology... more Abstract—Radio tomographic imaging (RTI) is an emerging device-free localization (DFL) technology enabling the localization of people and other objects without requiring them to carry any electronic device. Instead, the RF attenuation field of the deployment area of a wireless network is estimated using the changes in received signal strength (RSS) measured on links of the network. This paper presents the use of channel diversity to improve the localization accuracy of RTI.
Abstract Tracking of people via active badges is important for location-aware computing and for s... more Abstract Tracking of people via active badges is important for location-aware computing and for security applications. However, the human body has a major effect on the antenna gain pattern of the device that the person is wearing. In this paper, the gain pattern due to the effect of the human body is experimentally measured and represented by a first-order directional gain pattern model. A method is presented to estimate the model parameters from multiple received signal strength (RSS) measurements.
Abstract A wireless network can use the variance of measured received signal strength (RSS) on th... more Abstract A wireless network can use the variance of measured received signal strength (RSS) on the links in a network to infer the locations of people or objects moving in the network deployment area. This paper provides a statistical model for the RSS variance as a function of a person's position with respect to the transmitter (TX) and receiver (RX) locations.
Abstract—Device-free localization (DFL) enables localizing people by monitoring the changes in th... more Abstract—Device-free localization (DFL) enables localizing people by monitoring the changes in the radio frequency (RF) attenuation field of an area where a wireless network is deployed. Notably, this technology does not require people to participate in the localization effort by carrying any electronic device. This paper presents a DFL system for long-term residential monitoring. Due to the daily activities carried out by the people being monitored, the radio signals' propagation patterns change continuously.
ABSTRACT We propose to demonstrate real-time tag-free localization using radio tomography. In thi... more ABSTRACT 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.
Abstract Localization of users is an important part of location aware systems and smart environme... more 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.
Abstract–Radio frequency (RF) sensor networks are wireless sensor networks (WSNs) which use only ... more Abstract–Radio frequency (RF) sensor networks are wireless sensor networks (WSNs) which use only the received signal strength (RSS) to perform tasks such as device-free localization (DFL) and tracking of individuals. In these systems, people to be located do not participate in the localization effort by carrying any radio device or sensor. Instead, a static deployed wireless network measures RSS on its links and locates people based on the variations caused by the movements of people in the monitored area.
Abstract In this work, we evaluate the use of multiple sensors for secret key extraction. We find... more Abstract In this work, we evaluate the use of multiple sensors for secret key extraction. We find that the key generation rate increases linearly with the number of nodes. We show that the use of multiple nodes causes a significant mismatch in the extracted bits. We address the high bit mismatch problem by adding an iterative distillation stage to the key extraction process.
The broadcast nature of wireless medium has long been viewed as a trouble maker that causes the r... more The broadcast nature of wireless medium has long been viewed as a trouble maker that causes the radio channel interference, packet collision, information leakage, etc, and makes wireless networks more difficult to use than their wired peers. Our research, however, uses the complex behavior of the wireless channel to improve wireless network services. Specifically, we propose to leverage wireless physical layer measurements for location distinction.
Abstract A radio channel-based location distinction system monitors physical layer measurements o... more Abstract A radio channel-based location distinction system monitors physical layer measurements of received signals to detect if a transmitter has changed position since its previous transmission. This paper explores the design space for MIMO-based location distinction systems.
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Papers by Neal Patwari