1. Distance Estimation by Constructing The Virtual Ruler in Anisotropic Sensor Networks Yun Wang,Kai Li, Jie Wu Southeast University, Nanjing, China, Temple University, Philadelphia, PA INFOCOM 2010

2. Outline  Introduction  Method  Simulation  Conclusion

3. Introduction  Locations of sensor nodes are important for operations in WSNs.

4. Introduction  Performance heavily depends on the precision of distance estimation. Beacon node Sensor node

5. Introduction  In an anisotropic WSN, huge errors may be introduced into distance estimation because of irregular deployment. Beacon node Sensor node

6. Objective  Make the estimated distance ED(s,t) as close to its corresponding D(s,t) as possible. ED(s,t) D(s,t)D(s,t)

7. System model & Assumptions  Large number of sensor nodes in a WSN so that any node is able to obtain enough neighboring nodes with a limited flooding operation.

8. Overview  Constructing The Virtual Ruler Beacon node Sensor node Hole TN:Turning Node 10 12

9. Overview  Constructing The Virtual Ruler Beacon node Sensor node Hole TN:Turning Node 10 12

10. Calculation of Dominating Degree  Observation

11. Calculation of Dominating Degree  Obtain a set of surrounding nodes by executing a limited flooding operation from m. m Hole DD(n)=8 Avg_ DD(m)=7 DD(m)=6 Avg_ DD(m,n)-DD(m) =7-6=1 Threshold=2>1

12. Calculation of Dominating Degree  Obtain a set of surrounding nodes by executing a limited flooding operation from m. n1n1 n2n2 m n 3 5 7 Hole

13. Calculation of Dominating Degree n1n1 n2n2 m DD(m)=6 Avg_ DD(m)=9 Avg_ DD(m,n)-DD(m)=3 Threshold=2<3

14. Distance Estimation s t n1n1 Predefined parameter indicating the increase in Scale after a turning node 3 5 (3+5)*factor =8*0.85=6.8 6.8 hole

15. Distance Estimation s t n1n1 n2n2 n3n3

16. Review  The Virtual Ruler Beacon node Sensor node Hole TN:Turning Node

17. Simulation  Implemented the above algorithms in C++  5548 nodes are randomly deployed  Average node degree 6.2

18. Simulation DV-Distance Our method

19. Simulation

21. Conclusion  Design and evaluate a new distance estimation scheme for anisotropic WSNs.

22. Thanks for your attention!!