dynamic fine-grained localization in ad-hoc networks of sensors weikuan yu dept. of computer and...
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Dynamic Fine-Grained Localization in Ad-Hoc Networks of Sensors
Weikuan Yu
Dept. of Computer and Info. Sci.The Ohio State University
Presentation Outline
Problem Statement General Ideas and Related Work Current System at Study
Goals aimed Processing Steps Algorithms Critical Factors
Node and beacon placement Traffic and energy consumption
Conclusion
Problem Statement
Wireless sensors network widespread deployed signal sensing, emergence detection ground vibration
Location awareness is indispensable Immediate information transmission Quick routing of query Tracking of objects
Problem Statement
Problems with GPS Not work indoors High power consumption, short lifetime High cost
General Ideas and Related Work Localization Basics
Ranging RSSI ToA, TDoA AoA
Estimation
Related Work
RADAR Use RF signals to track indoor objects Offline and online phases High cost
Cricket location support Low cost for location awareness Use Ultrasound singals 4 x 4 feet granularity
BAT Centralize configuration Granularity at centimeters level
Both Cricket and BAT are infrastructures-based networks
ADLOS (Ad-Hoc Localization System) Goals
Ad-Hoc Sensor Network (Dynamic network) Fine granularity Low cost Distributed location awareness
Processing Phases Ranging Estimation
Radio Characteristics
Received Signal StrengthSusceptible to environmental changesshadowing, fading and even altitudeNo consistent model for some factorsRestriction: all nodes are at ground level
r: distance, X and n are constants
WINS nodes
WINS node RSSI characterization
ToA using RF and Ultrasound
Ultrasound Ranging characterization
Signal Strength and ToA Ranging ToA is more robust and fine-grained Susceptible to environmental changes Consider the combination of ToA and RF
Estimation Algorithms
Estimation Algorithms
Atomic MultilaterationBasic Formula
Weighted Combination
Iterative Multilateraion
Accuracy of Iterative Multilateration
Enhanced Iterative Multilateration
Collaborative Multilateration
Collaborative Multilateration
Node and Beacon Placement
Connectivity of a node
Probability of having a connected node
Number of nodes per unit area, lamda
Distribution of Connectivity Results
Required Beacon Nodes
Power Chacterization
Power consumption at different operational modes
Traffic with different implementation
Energy with different implementation
Conclusion
A new localization system scheme for Ad-Hoc wireless sensor networks Distributed, low cost Fine-grained
ToA ranging is better; hybrid can be even better Distributed is advocated for estimation
Less energy Less traffic Although less accurate
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