College of Engineering Anchor Nodes Placement for Effective Passive Localization Karthikeyan Pasupathy Major Advisor: Dr. Robert Akl Department of Computer Science and Engineering Karthikeyan Pasupathy Major Advisor: Dr. Robert Akl Department of Computer Science and Engineering
Outline Objective Overview of Sensor Networks Localization Motivation Anchor Node Placement Simulations and Results Conclusions and Future Directions Objective Overview of Sensor Networks Localization Motivation Anchor Node Placement Simulations and Results Conclusions and Future Directions 11/20/2015 2/46
Objective How to place anchor nodes for better passive localization ? 11/20/2015 3/46
Overview of Sensor Networks Made of tiny sensor nodes networked together Communicate wirelessly Made of tiny sensor nodes networked together Communicate wirelessly 11/20/2015 4/46
Overview of Sensor Networks Architecture 11/20/2015 5/46
Overview of Sensor Networks Limitations Deployment Short lifetime Unmanned Limitations Deployment Short lifetime Unmanned 11/20/2015 6/46
Overview of Sensor Networks Applications Military Reconnaissance, surveillance, shooter’s location, target tracking etc. Environment Track animals, birds, environmental conditions; detect forest fires, floods Applications Military Reconnaissance, surveillance, shooter’s location, target tracking etc. Environment Track animals, birds, environmental conditions; detect forest fires, floods 11/20/2015 7/46
Overview of Sensor Networks Applications Healthcare Monitor doctors, patients, drug administrators Hospitals – monitor physiological signals Medication – avoid wrong medication Applications Healthcare Monitor doctors, patients, drug administrators Hospitals – monitor physiological signals Medication – avoid wrong medication 11/20/2015 8/46
Overview of Sensor Networks Applications Domestic Smart home Smart kindergarten Industry Machine diagnosis; monitor radiation, material fatigue, product quality Applications Domestic Smart home Smart kindergarten Industry Machine diagnosis; monitor radiation, material fatigue, product quality 11/20/2015 9/46
Localization Where are these nodes ? Local position Global position How to localize? GPS Where are these nodes ? Local position Global position How to localize? GPS 11/20/ /46
Localization Localization Systems Centralized Distributed Localization Systems Centralized Distributed 11/20/ /46
Localization Centralized Not limited by algorithm More accurate results Traffic congestion Computational complexity Centralized Not limited by algorithm More accurate results Traffic congestion Computational complexity 11/20/ /46
Localization Distributed Usually iterative Algorithms generally energy efficient and self organizing Less accurate Distributed Usually iterative Algorithms generally energy efficient and self organizing Less accurate 11/20/ /46
Localization Different techniques Received Signal Strength (RSS) Time of Arrival (TOA) Angle of Arrival (AOA) Different techniques Received Signal Strength (RSS) Time of Arrival (TOA) Angle of Arrival (AOA) 11/20/ /46
RSS Signal strength Inverse Square law Error of several meters Less accurate Vulnerable to occlusions Signal strength Inverse Square law Error of several meters Less accurate Vulnerable to occlusions 11/20/ /46
Radio Hop Count Nodes separated by at most R Affected by hindrances Nodes separated by at most R Affected by hindrances 11/20/ /46
TOA Difference in propagation speed of signals 11/20/ /46
TOA More accurate Vulnerable to occlusions More accurate Vulnerable to occlusions 11/20/ /46
Angle of Arrival Phase / Time difference recorded by an array of microphones Expensive Bulkier Not practical to implement Sensor size shrinks Phase / Time difference recorded by an array of microphones Expensive Bulkier Not practical to implement Sensor size shrinks 11/20/ /46
Passive Localization Why passive ? Nodes are silent Advantages No external source for signals Can work with existing data Can be used in most outdoor applications Why passive ? Nodes are silent Advantages No external source for signals Can work with existing data Can be used in most outdoor applications 11/20/ /46
Passive Localization Disadvantages Centralized Not suitable for indoor applications Disadvantages Centralized Not suitable for indoor applications 11/20/ /46
Passive Localization Event detection Projected distances Localization Distance Matrix SVD Event detection Projected distances Localization Distance Matrix SVD 11/20/ /46
Passive Localization Localization Linear Combination coefficients Localization Linear Combination coefficients 11/20/ /46
Motivation Deployment of anchor nodes at specific position not easy Function of anchor nodes are different in passive localization Deployment of anchor nodes at specific position not easy Function of anchor nodes are different in passive localization 11/20/ /46
Anchor Node Placement Density Better to have more anchor nodes Deployment and hardware costs Redundancy Geometry No three anchor nodes may be linearly related Density Better to have more anchor nodes Deployment and hardware costs Redundancy Geometry No three anchor nodes may be linearly related 11/20/ /46
Simulations and results Assumptions: Propagation velocity – unity Clocks - time synchronized. Global events - distributed around the network. Signal processing – skipped Assumptions: Propagation velocity – unity Clocks - time synchronized. Global events - distributed around the network. Signal processing – skipped 11/20/ /46
Simulations and results Assumptions: Ideal case – no redundancy Global event – static sources Assumptions: Ideal case – no redundancy Global event – static sources 11/20/ /46
Simulations and Results User Interface: 11/20/ /46
Simulations and Results Localization Error: 11/20/ /46
Simulations and Results Random deployment n = 10, k = 3 11/20/ /46
Simulations and Results Random deployment n = 10, e = 20 11/20/ /46
Simulations and Results Manual deployment – Sparse network (L err = 15.52%) ∆ Sensor Nodes + Computed position ● Anchor Nodes 11/20/ /46
Simulations and Results Manual deployment – Sparse network (L err = 9.68 %) 11/20/ /46
Simulations and Results Manual deployment – Sparse network (L err = 5.75 %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Simulations and Results Manual deployment – Dense network (L err = %) 11/20/ /46
Conclusions Investigated positioning of anchor nodes Better to deploy anchor nodes at the center of the network Less linearity – Better localization Placing at right angles Real situations may be different Investigated positioning of anchor nodes Better to deploy anchor nodes at the center of the network Less linearity – Better localization Placing at right angles Real situations may be different 11/20/ /46
Future Directions Implementation on motes. Third dimension Time synchronization Mobile global events Implementation on motes. Third dimension Time synchronization Mobile global events 11/20/ /46
Questions ? 11/20/ /46