node reclamation and replacement for long-lived sensor networks bin tong, wensheng zhang, and chuang...
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Node Reclamation and Replacement for Long-lived Sensor Networks
Bin Tong, Wensheng Zhang, and Chuang WangDepartment of Computer Science, Iowa State University
Guiling WangDepartment of Computer Science, New Jersey Institute of Technology
IEEE SECON 2009
Outline Introduction Goal System Model Node reclamation and replacement The ARTS Scheme Performance Evaluation Conclusion
Introduction Wireless Sensor Network
Power by batteries
Introduction Wireless Sensor Network
Environmental sources Deployment Reclamation and Replacement
Introduction Motivation and Goal
Providing a guaranteed Quality of Service A sufficient number of sensor nodes being alive
Minimizing the overhead caused by the reclamation and replacement The travel distance of the MR is minimized in the long run
System Model System Architecture
The system consists of a mobile repairman (MR), an energy station (ES) A WSN composed of groups of sensors surrounding the posts The MR traverses the network periodically to reclaim sensors having low or no
energy and replace them with fully-charged sensors
group
Assumptions Time is divided into phases of a constant length. A certain number of phases co
mpose a round, the length of which is denoted as l. The MR visits each post at most once every round.
A sensor has two modes: active and sleep. At the beginning of each phase, all sensors in each group should wake up and p
articipate in the duty-cycle scheduling.
Node reclamation and replacement
Surveillance Number = 6
group
…phase1 phase2 phase i
Wait time
The ARTS Scheme Adaptive rendezvous-based two-tier scheduling scheme
Local-Tier Scheduling Global-Tier Scheduling
round j
round j+11. Visit time 2. Number of sensors to be reclaimed/replaced
residual energy
Collects information for the round j+2
phase 1phase 2
The ARTS Scheme Local-Tier Scheduling
Quality of Service is guaranteed ( ≧ Nmax)
Remaining energy in sensors to be reclaimed/replaced should be as small as possible
Initial phase j
Scheduling1. Nd
2. Surveillance number3. t
Scheduling phase j
Nd: the number of sensors in the groupt: the number of remaining phases before the next replacement/reclamation
Nmax × tδ
The ARTS Scheme Local-Tier Scheduling
Quality of Service is guaranteed ( ≧ Nmax)
Remaining energy in sensors to be reclaimed/replaced should be as small as possible
1
3
5
0
4
2
6
Nd : the number of sensors in the groupt : the number of remaining phases before the next replacement/reclamationei: the amount of sensor i remaining energyδ: be the amount of energy consumedby an active sensor per phase
Sorted
L1 = <u0, · · · , um−1>
ei ≧ tδ
L2 = <um, · · · , uNd-1>
ei < tδ
Scheduling
check
remaining energy in L2
m × tδ
The ARTS Scheme Local-Tier Scheduling
Quality of Service is guaranteed ( ≧ Nmax)
Remaining energy in sensors to be reclaimed/replaced should be as small as possible
L1 L2 L1 L2 L2L1
δ=1, Nmax= 5
greedy scheduling policy:
Fail
6 (5-3)3*1=6≧ 2 < (5-3)3*1=6
The ARTS Scheme Local-Tier Scheduling
Controlled-greedy Algorithm
δ=1, Nmax= 5
2 < (5-3)3*1=6
x
The ARTS Scheme Global-Tier Scheduling
The total travel distance of the MR is minimized The remaining energy of sensors to be replaced is minimized
group i
round j
information of round j+1
visiting time and replacement number in round j +2 for group i
The ARTS Scheme Global-Tier Scheduling
The total travel distance of the MR is minimized The remaining energy of sensors to be replaced is minimized
Calculation of Replacement Numbers : Choose least energy sensors
l : the length of a roundτ : the lifetime of sensor if being active all the time
(l/τ) × Nmax= 3 × Nmax
Case: l >τ
Nmax
Case: l ≦τ
To guard against the worst case scenario when Nmax nodes are needed to be active all the time.
j j+1 j+2
time
j=1,2:
j >2:
The ARTS Scheme Global-Tier Scheduling
The total travel distance of the MR is minimized The remaining energy of sensors to be replaced is minimized
Calculation of the Travel Schedule for the MR Data Structure in round j+2
Table R
Deadline
e(i, p): the total residual energy in the sensors to be reclaimed/replaced in group gi at phase p
Data Structure in round j+2 G(V, E, W (V ), W (E), R)
V = {gi | 0 ≤ i ≤ n}
W (V) ={Nr(1, j+2), · · · , Nr(n, j+2)}
= (t1, t2, · · · , tn)︰ a visiting time vector
D = ︰ is the total traveling distance for the MR
= (2, 1 , 3, 4 )
g1
g2
g3g4
Nr(1, j+2)
Nr(2, j+2)
Nr(3, j+2)Nr(4, j+2)
g1
g2
g3g4
Nr(1, j+2)
Nr(2, j+2)
Nr(3, j+2)Nr(4, j+2)
The ARTS Scheme Global-Tier Scheduling
The total travel distance of the MR is minimized The remaining energy of sensors to be replaced is minimized
Calculation of the Travel Schedule for the MR How decide the vector to minimize the weight
g1
g2
g3g4
Nr(1, j+2)
Nr(2, j+2)
Nr(3, j+2)Nr(4, j+2)
Global-Tier Scheduling The total travel distance of the MR is minimized The remaining energy of sensors to be replaced is minimized
Calculation of the Travel Schedule for the MR
g1
g3
g7
g6
g2
g4
ES
Super Tour 1
Super Tour 2M
[10]
[10] T. Liebling, D. Naddef, and L. A. Wolsey, “On the capacitated vehicle routing problem,” Mathematical Programming, 2003
g5
Performance Evaluation Simulation Parameter
lifetime τ 4000 minutes
phase length 10 minutes
round l 4000 minutes
Nmax 8 sensors/group
1000 m
1000 m
36 groups
16 sensors40 sensors
Performance Evaluation Simulation ResultTradeoff between Residual Energy in Sensors to Be Reclaimed/Replaced and MR’s Travel Distance
Comparison with Optimal Solution
Performance Evaluation Simulation Result
Impact of MR’s Capacity
Impact of Round Length
Conclusion A node replacement and reclamation (NRR) strategy and an adaptive rende
zvous-based two-tier scheduling (ARTS) scheme to meet the challenges of designing an efficient WSN for long-term tasks
Extensive simulations have been conducted to verify the effectiveness and efficiency of the ARTS scheme.
Future Work Plan to explore other design choices for the NRR System, extend
the current design of the ARTS scheme, and set up real testbed to evaluate the design.
Thank you~