Computer Engineering and Networks Laboratory
description
Transcript of Computer Engineering and Networks Laboratory
Positioning in Ad-Hoc Networks-
Directions and Results
Jan BeutelComputer Engineering and Networks Lab
Swiss Federal Institute of Technology Zurich
August 10, 2002
Computer EngineeringComputer Engineeringand Networks Laboratoryand Networks Laboratory
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Ad-Hoc Network Scenarios
•Low power•Small size•Very large population
•No infrastructure necessary•Varying population density•Multihop environment•Partitioning
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Positioning: The Problem
Finding the position of networking nodes
Relative vs. Absolute Positioning Mode
Reference Positions, Map
Database
Other Networking Nodes, Distance and Geometric
Topology
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RSSI Samples Over Distance - Free Space
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LSNR Avg
RSNR Avg 802.11b
Bluetooth
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Redundant Triangulation
Every node executes
•Identification of neighbors
•Establishing range estimates
•Maintaining a set of a minimum of 3 linear equations to the neighbors
•Solve for MMSE
Dissemination of data over the network
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Redundant Triangulation and Filtering
Average over 25 individual triangulations with 50% range error
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Delaunay Mesh of 25 Networked Nodes
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Solution on 25 Ranges and 50% Error
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50 Solutions and Mean
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Zoom on Error
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dx 0.0054
dy 0.0058
1% position error
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Influence of Range Quantization
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Very Large Errors and Topology
3 anchors ~ 94%
4 anchors ~ 6%
5 anchors >1%
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Influence of Border Regions
Center I
Edge II
Corner III
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Ad-hoc Network Simulation Environment
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The TERRAIN Algorithm .
• Triangulation via Extended Range and Redundant Association of Intermediate Nodes
• Algorithm creates local maps
• Every node waits to beincluded in 3 maps
• Extended rangescalculated fromrespective maps
• Triangulation node basedon extended ranges
• Network-wide iterations
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radio range
extended range
intermediate node