Load Balanced Routing with Constant Stretch for Wireless Sensor Network with Holes

1. Load Balanced Routing with Constant Stretch for Wireless Sensor Network with Holes Nguyen Phi Le, Nguyen DucTrong and Nguyen Khanh Van Ha Noi University of science and technology

2. Agenda • Background • Related works • Problem statement and goals • Proposed scheme • Strategy to choose the forbidding area • Hole bypassing routing protocol • Performance evaluation • Conclusion and future work

3. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

4. Background • Geographic routing • Uses location information of the nodes • Each node knows the location of the neighbors and the destination • Achieves near optimal path with network without holes

5. Background • Geographic routing with holes • Hole diffusion problem

6. Background • Geographic routing with holes • Hole diffusion problem • Routing path enlargement problem

7. Background • Common approach • Constructing a forbidding area around the hole • Nodes know the hole in advance • Routing the packet along optimal path outside the forbidding area

8. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

9. Related works • Target the hole diffusion problem The forbidding area is very simple The dissemination cost is small Virtual hexagon [H.Choo, ICOIN’11] Virtual Circle [F.Yu, JCN 2009] Virtual ellipse [Y.Tian, ICC’08]

10. Related works • Hole diffusion problem has not been solved thoroughly • Static forbidding area • Traffic is concentrated around the forbidding area • Routing path is enlarged in some cases

11. Related works • Target the routing path enlargement problem D GOAL [Transaction on parallel and distributed computing, 2011] Visibility graph [G.Tan, infocom 2009] S Constant stretch Hole BUT Convex hull Data congestion on the boundary of the convex hull

12. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

13. Problem statement • Hole diffusion problem has not been solved thoroughly • Static forbidding area • Traffic is concentrated around the forbidding area • None of the existing schemes solves both of the two problems

14. Goal • Finding the optimal forbidding area • Constant stretch • Load balancing • Small dissemination cost • Propose a hole bypassing routing scheme which • Has a constant stretch • Solves the problem of hole diffusion thoroughly

15. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

16. Theoretical model • Considering networks with only one hole • Modeling the geographic S-D routing path as the Euclidean line between S and D Real geographic routing path Euclidean routing path

17. Theoretical model • Euclidean stretch of the forbidding area to the hole Hole Forbidding area Shortest Euclidean routing path bypassing the hole Euclidean routing path bypassing the forbidding area

18. Strategy to choose the forbidding area • Constant stretch • Load balancing • Small dissemination cost

19. Strategy to choose the forbidding area • The shortest Euclidean path bypassing a polygon • broken line through the vertices of the convex hull Convex hull of polygon P: a convex polygon which covers P and its vertices are the vertices of P

20. Strategy to choose the forbidding area • The shortest Euclidean path bypassing a polygon • broken line through the vertices of the convex hull Is the convex hull the best forbidding area ??? • The Euclidean stretch of the convex hull to the hole is 1

21. Strategy to choose the forbidding area • The shortest Euclidean path bypassing a polygon • broken line through the vertices of the convex hull The number of the vertices of the convex hull maybe very large The dissemination cost is large too

22. Strategy to choose the forbidding area • The forbidding area should be a convex polygon Hole bypassing routing path Hole Forbidding area

23. Strategy to choose the forbidding area • If P is a n-gonwith equal angles such that P covers the hole and each edge of P contains at least one vertex of the hole, then Euclidean stretch of P to the hole is upper bounded by • We choose the octagon with the equal angles as the forbidding area • The Euclidean stretch does not exceed

24. Strategy to choose the forbidding area • Constant stretch • Load balance • Small dissemination cost Traffic concentration around the boundary of the forbidding area Hole Forbidding area

25. Strategy to choose the forbidding area • The Euclidean stretch depends on • Perimeter of the forbidding area • Distance between the source and the destination • The larger the distance, the smaller the Euclidean stretch • The Euclidean stretch does not depends on • The position of the forbidding area • Dynamic forbidding area • The size and the position are packet specific

26. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

27. Proposed protocol detail • Initial network setup • Hole bypassing protocol

28. Proposed protocol detail • Initial network setup • Identifying hole boundary • Determining core polygon • Disseminating information of core polygon to a restricted area • Hole bypassing protocol 1. Identifying hole boundary 2. Determining core polygon 3. Disseminating core polygon 4. Hole bypassing protocol

29. Initial network setup • Core polygon construction 2. Construct another rectangle circumscribing the hole with edge directions of angle of to the first 1. Construct a rectangle circumscribing the hole

30. Initial network setup • Core polygon construction 3. The intersections of the two rectangles form the core polygon

31. Initial network setup • Core polygon information dissemination Region 1 Region 2 • Dissemination area is restricted by predefined threshold δ pC: perimeter of the core polygon; l(N): distance from N to the core polygon ; β(N): view limit from N to the core polygon

32. Proposed protocol detail • Initial network setup • Identifying hole boundary • Determining core polygon • Disseminating information of core polygon to a restricted area • Hole bypassing protocol 1. Identifying hole boundary 2. Determining core polygon 3. Disseminating core polygon 4. Hole bypassing protocol

33. Hole bypassing protocol • The packet is initiated in region 2 Region 1 Region 2

34. Hole bypassing protocol • The packet is initiated in region 1 (or arrived at a node in region 1) Region 1 I Region 2 • Determines the forbidding area (A-polygon): Image of the core polygon through a homothetic transformation • The center is chosen randomly • The scale factor > 1 is computed based on source-destination distance

35. Hole bypassing protocol • The packet is initiated in region 1 (or arrived at a node in region 1) Region 1 I Region 2 Scale factor is computed based on the source-destination distance ↓ Constant stretch of routing path Random selection of I ↓ Forbidding area is different per packet

36. Hole bypassing protocol • The packet is initiated in region 1 (or arrived at a node in region 1) Region 1 I Region 2 • Determines shortest Euclidean path which bypasses the A-polygon • Virtual anchors: vertices of A-polygon • Routes the packet to the virtual anchors

37. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

38. Performance evaluation • Theoretical analysis • Proves the constant Euclidean stretch of the proposed protocol • Simulation • Compares performance with existing protocols

39. Theoretical analysis • Constant stretch • Euclidean stretch does not exceed to (~1.09+δ） ( predefined parameter)

40. Simulation • Benchmarks • Virtual Circle [F.Yu, transaction on communication and network 2009] • Virtual hexagon [H.Choo, ICOIN’11] • Convex hull [Transaction on parallel and distributed computing, 2011] • Evaluation metrics • Stretch in hop-count • The ratio between the hop-count of the routing path using routing protocol and the optimal routing path. • Energy consumption of individual sensor nodes • Energy overhead • The extra energy caused by the initial network setup phase in our protocol.

41. Simulation • Simulation scenario • Simulator :NS2 • Network area: 1000m x 1000m • Sensor nodes: 1500 • Number of the hole: 1 • Number of the vertices of the hole: 52 • Simulation time: 500s • Number of source-destination pair: 100 pairs • Packet transmission frequency: 1packet/1s (Victor Shnayder et al., Simulating the power consumption of large scale sensor network applications, SenSys’04 )

42. Simulation • Simulation result • Stretch • Smaller than “virtual hexagon”, “virtual circle” • Greater than “Goal” but the difference is not much • Less than 1.2 (with δ=1) • Does not increase when decreasing the distance between source-destination

43. Simulation • Simulation result • Energy consumption of individual sensor nodes • “Goal” is the worst • The proposed scheme is the most balanced compared to the existing protocols GOAL Proposed scheme( Virtual hexagon Virtual circle

44. Simulation • Simulation result • Energy overhead • Decreases with the increasing of the stretch • Just accounts for only 0.095% of the entire energy even in the worst case

45. Agenda • Background • Related works • Problem statement and goals • Strategy to choose the forbidding area • Our proposed routing scheme • Performance evaluation • Conclusion and future work

46. Conclusion and future work • Conclusion • We proposed a routing protocol to bypass the hole • Solves the problem of hole diffusion • Ensures a constant stretch • Euclidean stretch , theoretically • Proposed scheme outperforms existing protocols by simulation • Hop-count stretch <1.2 (with =1) • Future work • Consider the network with multiple holes • Compare performance of our protocol with non-geographic routing protocols

47. Thank you for your attention !