coverage and energy tradeoff in density control on sensor networks yi shang and hongchi shi...
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Coverage and Energy Tradeoff in Density Control
on Sensor NetworksYi Shang and Hongchi Shi
University of Missouri-Columbia
ICPADS’05
OutlineOutline
Introduction
Density Control ProtocolsNODC vs. OGDCDODCDNODCA
Experimental ResultsConclusions
IntroductionIntroduction Density Control
a technique for prolonging network’s lifetime while providing sufficient sensing coverage
determine when and which sensors should be powered up and which should power saving
Different applications require different degrees of sensing coverage complete coverage high percentage coverage
This paper consider the tradeoff between energy usage and coverage
Density Control ProtocolsDensity Control Protocols
NODC vs. OGDC ( Non-Overlapping vs. Optimal Geographical)
GODCOverlap= (20.9%)
NODCGap= (9.31%)
Density Control ProtocolsDensity Control Protocols
Assumptionsinterested sensing space is much larger than
the sensing range of each sensor noderadio range is at least twice of the sensing
rangeEach node knows its position
Density Control ProtocolsDensity Control Protocols
States: ON/OFF/UndecidedSelection of starting node
selecting starting node with probability p if its power exceeds a pre-determined threshold Pt
sets a backoff timer of τ1 secondsbroadcast a power-on message after backoff
position of the senderdirection α : uniform distribution in [0, 2π]
Density Control ProtocolsDensity Control Protocols
States: ON/OFF/UndecidedSelection of starting node
selecting starting node with probability p if its power exceeds a pre-determined threshold Pt
sets a backoff timer of τ1 secondsbroadcast a power-on message after backoff
position of the senderdirection α : uniform distribution in [0, 2π]
Density Control ProtocolsDensity Control Protocols
Actions: when receiving a power-on message checks the ratio of its sensing area covered by its
“ON” neighbors to its overall sensing area is over a predetermined threshold (turn-off threshold θ )
Rule R1: first power-on message received from starting node
Rule R2: first power-on message received from non-starting node
Rule R3: second power-on message received Rule R4: receive more than two power-on messages
Rule1
Rule3
Density Control ProtocolsDensity Control Protocols
Rule4: receive more than two power-on messages
1. None of the coverage areas of the senders overlaps
2. previous senders do not overlap andnew sender overlaps with previous senders
3. previous senders do not overlap and new sender overlaps with previous senders
AB
C
A B
CD D
ONDCDONDCDDensity Control Protocol Based on DistancesDensity Control Protocol Based on Distances
NODCD does not require the location informationRule R1: The message is the first power-on
message received.
Rule R2: More than one power-on messages have been received.
ONDCAONDCADensity Control with Adjustable Sensing RangesDensity Control with Adjustable Sensing Ranges
Turn-off threshold θ, 0 ≤ θ ≤ 1,Two iterations as follows
The optimal values of θ, r2 ????
Experimental ResultsExperimental Results
region of interest : 50m x 50m square.sensing range: rs = 5m.
constant c = 10/rs2
Experimental ResultsExperimental Results
88% vs. 85% 41 vs. 34 75 vs. 75
Experimental ResultsExperimental Results
Experimental ResultsExperimental Results
ConclusionsConclusions
three new density control protocols that apply new strategies in trading the coverage vs. energy usagedistributedeasy to implementlow computation/communication costs