Post on 18-Jan-2018
description
Decentralized Energy-Conserving and Coverage-Preserving Protocols
for Wireless Sensor Networks
Chi-Fu Huang, Li-Chu Lo, Yu-Chee Tseng, and Wen-Tsuen ChenDepartment of Computer Science and Information Engineering National Chiao-Tung UniversityDepartment of Computer Science National Tsing-Hua UniversityIEEE International Symposium on Circuits and System (ISCAS’05)
Outline Introduction 1-Coverage-Preserving Protocol
Basic Energy-based
Simulation Results Conclusion
Introduction This paper proposed protocols are
based on a model similar to that of [8], but improve it First, reduce the computational complexity Second, balance sensors’ energy
expenditure [8] Differentiated surveillance for
sensor networks. (SenSys 2003)
Introduction Goals
Provide an approach for nodes to decide their sleep/work mode schedules:
Guarantee Full-coverage Redundant nodes go to sleep to save
energy and extend system lifetime
Introduction -Differentiated surveillance for sensor networks Work/Sleep schedule for a single point
A B
C
Node A
Node B
Node C
0 10030 70
10 60
5 45
time
Awake Asleep
Point XPoint X
Point X
10
Introduction -Differentiated surveillance for sensor networks Work/Sleep schedule for a single point
A B
C
Node A
Node B
Node C
Awake
0 10030 70
60
5 45
time
Asleep
Point X
Point x is covered by at least one node’s sensing area at any time
tA
C
B
Introduction -Differentiated surveillance for sensor networks
Point X
t
0
100
105
20
refC
40
refA
90
refB
120
refC
100
30 655105
Tfront Tend
Reference randomly selected from [0, T)Each node broadcasts tuple (location, reference)
Introduction -Differentiated surveillance for sensor networks
frontT frontT frontTendT endT endT
Sensing PhaseInit Phase
ref ref
Round 0(Duration T) Round 1 Round n
………
Work Schedule: [n×T + ref – Tfront ﹐ n×T + ref + Tend]
ref
D
C
BA
Introduction -Differentiated surveillance for sensor networks Schedules for All Grid Points
E
Grid Points
Introduction -Differentiated surveillance for sensor networks
1-Coverage-Preserving Protocol-Assumption
Sensors Si , i = 1,…,n Location (Xi , Yi ) Sensing Range ri
Each Sensor can switch between the active mode and the sleeping mode
Two sensors Si and Sj are neighbors If they have non-empty overlapping sensing
region Sensors can communicate with his neighbors
1-Coverage-Preserving Protocol– Basic
The structure of sensors’ working cycles
1. Location (Xi ,Yi )
2. Sensing range ri
3. Reference time Refi
1-Coverage-Preserving Protocol – Basic
Initialization phase Each sensor Si broadcasts a HELLO packet after random backoff
Location (Xi , Yi ) Sensing range ri
Reference time Refi randomly selected from [0, Trnd ) Each sensor Si can calculate it own working schedule in the sensing phase
To calculate Fronti and Backi
1-Coverage-Preserving Protocol – Basic
Each sensor’s Fronti and Backi should be carefully selected to ensure that the sensing area is sufficiently covered
To achieve this goal, we use intersection points If all intersection points in the target area
A are covered by any sensor’s sensing range, the target area A is sufficiently covered
m
1-Coverage-Preserving Protocol– Basic
t
t
0 2
Ref1
9
Ref2
11
Ref3
20
5.5 16.5
Front1=5.5Back1
=3.5
20
n
q
S1
S3S5
S2S4
p
r
Schedule for p
Front1
2 11 205.5
9 2 203.5
0
1-Coverage-Preserving Protocol– Basic
1-Coverage-Preserving Protocol – Energy-base
Each sensor Si is aware of its current remaining energy, denoted as Ei
Each sensor Si broadcasts its Ei in the HELLO packet
1-Coverage-Preserving Protocol – Energy-base
Fronti and Backi of the sensor Si are chosen based on Ei
Simulation Result 100 x 100 square are 150 sensors, randomly generated Sensing range 25 A working cycle (Tw_cycle) include 5
rounds To set up sensors’ initial energies
Can active from 1 to 50 complete rounds in randomly selected manner
Simulation Result
Simulation Result
Conclusion The paper protocols improve the
results in several sense Significantly reduce the computational
complexity Use intersection points
Further balance sensors’ energy expenditure
Use sensors’ remaining energy
Thank you !!