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Wensheng Zhang and Guohong Cao. Optimizing tree reconfiguration for mobile target tracking in sensor networks. Dynamic Convoy Tree-based Collaboration (DCTC). Constructing the Initial Convoy Tree Apply existing root election algorithm Other node connect to a neighbor closest to the root
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Wensheng Zhang and GuohongCao Optimizing tree reconfiguration for mobile target tracking in sensor networks
Dynamic Convoy Tree-based Collaboration (DCTC) • Constructing the Initial Convoy Tree • Apply existing root election algorithm • Other node connect to a neighbor closest to the root • Collecting sensing data via the tree • Root receives reports and processes them • Tree expansion and pruning • Apply existing prediction schemes to involve new nodes • Prune useless nodes (too far from the target) • Change the root node • The root node makes all decisions
Energy consumption • E = Ed + Et (for each time interval) • Ed: Data collection • Et : Tree reconfiguration • Min-cost tree Problem of Optimizing Tree Reconfiguration Equal to Find a min-cost convoy tree sequence
Optimizing Tree Reconfiguration Schemes • A convoy tree is reconfigured in two steps • The current root is replaced by a new one • The remaining part of the tree is reconfigured to reduce the communication overhead
Root Replacement • R predicts Lt+1 • Replace R, if DR, Lt+1 >dr • dr • Large: high overhead on data collection • Small: high overhead on tree reconfiguration • How to determine dr?
How to determine dr? • k(v) = dr/ v • time units a target needs to travel through dr • Nodes send reports to Root on every time unit • The average energy consumption between two root replacement:
Optimized Complete Reconfiguration (OCR) • The current root decides and initiates root replacement • New root notifies all nodes this change. • Reconfigure the tree: Each node connects to the neighbor closest to the new root node.
OCR overhead analysis • Data collection energy: • Tree reconfiguration energy:
Optimized Interception-based Reconfiguration (OIR) • The current root decides and initiates root replacement • New root notifies all nodes this change. • Reconfigure the tree: Each node checks whether it needs to change its parent node.
OCR vs OIR • OCR:Higher priority on Data Collection • OIR: Higher priority on Tree Reconfiguration • High target velocity, small sd/sc, small ds/d
Thanks Q&A