OPTIMIZING TREE RECONFIGURATION FOR MOBILE TARGET TRACKING IN SENSOR NETWORKS
Wensheng Zhang and Guohong Cao
Dynamic Convoy Tree-based Collaboration (DCTC)
1. Constructing the Initial Convoy Tree Apply existing root election algorithm Other node connect to a neighbor closest to the
root2. Collecting sensing data via the tree
Root receives reports and processes them3. 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 toFind a min-cost convoy tree sequence
Optimizing Tree Reconfiguration Schemes
A convoy tree is reconfigured in two steps1. The current root is replaced by a new
one2. 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.
OIR overhead analysis
OCR vs OIR
OCR:Higher priority on Data Collection OIR: Higher priority on Tree Reconfiguration
High target velocity, small sd/sc, small ds/d
ThanksQ&A
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