Real-Time Analysis of Correlations Between On-Body Sensor Nodes

The topology of a body sensor network has, until recently, often been overlooked; either because the layout of the network is deemed to be sufficiently static (”we always know well enough where sensors are”), we always know exactly where the nodes are or because the location of the sensor is not inherently required (”as long as the node stays where it is, we do not need its location, just its data”). We argue in this paper that, especially as the sensor nodes become more numerous and densely interconnected, an analysis on the correlations between the data streams can be valuable for a variety of purposes. Two systems illustrate how a mapping of the network’s sensor data to a topology of the sensor nodes’ correlations can be applied to reveal more about the physical structure of body sensor networks

Non-line-of-sight Node Localization based on Semi-Definite Programming in Wireless Sensor Networks

An unknown-position sensor can be localized if there are three or more anchors making time-of-arrival (TOA) measurements of a signal from it. However, the location errors can be very large due to the fact that some of the measurements are from non-line-of-sight (NLOS) paths. In this paper, we propose a semi-definite programming (SDP) based node localization algorithm in NLOS environment for ultra-wideband (UWB) wireless sensor networks. The positions of sensors can be estimated using the distance estimates from location-aware anchors as well as other sensors. However, in the absence of LOS paths, e.g., in indoor networks, the NLOS range estimates can be significantly biased. As a result, the NLOS error can remarkably decrease the location accuracy. And it is not easy to efficiently distinguish LOS from NLOS measurements. In this paper, an algorithm is proposed that achieves high location accuracy without the need of identifying NLOS and LOS measurement.Comment: submitted to IEEE ICC'1

Effects of Spatial Randomness on Locating a Point Source with Distributed Sensors

Most studies that consider the problem of estimating the location of a point source in wireless sensor networks assume that the source location is estimated by a set of spatially distributed sensors, whose locations are fixed. Motivated by the fact that the observation quality and performance of the localization algorithm depend on the location of the sensors, which could be randomly distributed, this paper investigates the performance of a recently proposed energy-based source-localization algorithm under the assumption that the sensors are positioned according to a uniform clustering process. Practical considerations such as the existence and size of the exclusion zones around each sensor and the source will be studied. By introducing a novel performance measure called the estimation outage, it will be shown how parameters related to the network geometry such as the distance between the source and the closest sensor to it as well as the number of sensors within a region surrounding the source affect the localization performance.Comment: 7 Pages, 5 Figures, To appear at the 2014 IEEE International Conference on Communications (ICC'14) Workshop on Advances in Network Localization and Navigation (ANLN), Invited Pape

Photoelasticity based dynamic tactile sensor

The paper presents design, construction and testing of a photoelasticity based dynamic sensor which is capable of detecting slip as well as providing normal force information. Starting with investigations into mechanism of slip, an approximate model of the sensor has been developed. This model explains the design improvements necessary to provide continuous signal during slip. The theoretical model also helps identify various sensor parameters to characterize the sensor. The developed sensor has been compared with other existing sensors and the experimental results from the sensor have been discussed for the type of signal the sensor provides. The sensor is also calibrated for normal force. The sensor is novel in the sense that it offers dynamic slip signal as well as the normal force information from a single contact location, it provides continuous signal during slip, and it has small size which can be easily incorporated into robotic fingers. The sensor has an edge over other existing sensors that its design is simple yet it provides strong signals which are largely unaffected by external disturbances. Copyright © 2005 by ASME

Maintaining trajectory privacy in mobile wireless sensor networks

Mobile wireless sensor networks (MWSN) is a subdomain of wireless sensor networks in which sensors and/or sinks are mobile. In this study, we propose a scheme for providing trajectory privacy of mobile sink nodes. The proposed scheme is based on random distribution of data packets. Moreover, sensor nodes do not use location information of the mobile sink or its trajectory. We performed simulation based and analytical performance evaluations for the proposed scheme. The results show that a network with up to 99% data delivery rate can be obtained by appropriate configuration while maintaining a fair level of trajectory privacy of the mobile sink node