1. On Reducing Broadcast Transmission Cost and Redundancy in Ad Hoc Wireless Networks Using Directional Antennas Minglu Li ( Department of Computer Science and Engineering, Shanghai Jiao Tong University ) Ling Ding, Yifeng Shao ( Department of Computer Science, Texas University at Dallas, Richardson ) Zhensheng Zhang ( Argon ST (formerly SDRC) Inc., San Diego, CA ) BoLi ( Department of Computer Science and Engineering, Hong Kong University ) IEEE Transactions on Vehicular Technology, TVT 2010

2. Page: 2 WMNL Introduction Virtual Link Reduction-based Protocol Performance Evaluation Conclusion

3. Page: 3 WMNL Broadcasting is essential in ad hoc networks for –Data dissemination –Route discovery –Resource discovery –Management –…–…

4. Page: 4 WMNL Broadcasting mechanism can categorize into three types –Simple flooding –Probability based –Neighbor knowledge based Waste too much network bandwidth Consume too much energy Waste too much network bandwidth Consume too much energy

5. Page: 5 WMNL Broadcasting mechanism can categorize into three types –Simple flooding –Probability based –Neighbor knowledge based Waste too much network bandwidth Consume too much energy Waste too much network bandwidth Consume too much energy Full delivery may not be guaranteed

6. Page: 6 WMNL Broadcasting mechanism can categorize into three types –Simple flooding –Probability based –Neighbor knowledge based Waste too much network bandwidth Consume too much energy Waste too much network bandwidth Consume too much energy Full delivery may not be guaranteed More efficient than flooding and probability based methods

7. Page: 7 WMNL Omnidirectional antennas in wireless ad hoc networks are highly inefficient in terms of power and capacity. –Rather small portion of the transmission power is actually intercepted by the antenna of the intended receiver Receiver Unwanted and harmful interference 10  350  Sender

8. Page: 8 WMNL Directional antennas achieve better signal-to-noise ratio and reduce interference. Sender Receiver

9. Page: 9 WMNL Several protocols have been proposed toward efficient broadcasting using directional antennas. However, most of them –Are probability based approaches –Rely on location information –Rely on Angle-of-Arrival (AoA) information –Assume specific antenna models

10. Page: 10 WMNL This paper focus on applying directional antennas to broadcasting. –Achieving full delivery –Reducing transmission cost and redundancy –Reducing bandwidth consumption –No location or AOA information is used –Using a general antenna model

11. Page: 11 WMNL There is no packet collision. –Otherwise, full delivery cannot be achieved even under flooding.

12. Page: 12 WMNL General antenna model. –Directional beams do not have to be regular, aligned, or nonoverlapping. Directional transmission, Omnidirectional reception

13. Page: 13 WMNL VLR -based Protocol

14. Page: 14 WMNL VLR -based Protocol

15. Page: 15 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 First round exchanged

16. Page: 16 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 1 2 2 N(i)N(i)c Dx→yDx→y 2 N(d)N(d)c Dx→yDx→y 1 N(a)N(a)c Dx→yDx→y 2 First round exchanged

17. Page: 17 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 3 4 4 N(i)N(i)c Dx→yDx→y 2 N(d)N(d)c Dx→yDx→y 1 N(a)N(a)c Dx→yDx→y 2 N(c)N(c)adi Dx→yDx→y 434 First round exchanged

18. Page: 18 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 N(i)N(i)cjh Dx→yDx→y 241 N(d)N(d)acefg Dx→yDx→y 41322 N(a)N(a)cbd Dx→yDx→y 242 N(c)N(c)adi Dx→yDx→y 434 N(b)N(b)a Dx→yDx→y 2 N(j)N(j)i Dx→yDx→y 2 N(h)N(h)i Dx→yDx→y 3 N(g)N(g)def Dx→yDx→y 433 N(f)N(f)deg Dx→yDx→y 441 N(e)N(e)dfg Dx→yDx→y 121 First round exchangedSecond round exchanged

19. Page: 19 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 N(i)N(i)cjh Dx→yDx→y 241 N(d)N(d)acefg Dx→yDx→y 41322 N(a)N(a)cbd Dx→yDx→y 242 N(c)N(c)adi Dx→yDx→y 434 N(b)N(b)a Dx→yDx→y 2 N(j)N(j)i Dx→yDx→y 2 N(h)N(h)i Dx→yDx→y 3 N(g)N(g)def Dx→yDx→y 433 N(f)N(f)deg Dx→yDx→y 441 N(e)N(e)dfg Dx→yDx→y 121 Second round exchanged

20. Page: 20 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 N(i)N(i)cjh Dx→yDx→y 241 N(a)N(a)cbd Dx→yDx→y 242 N(c)N(c)adi Dx→yDx→y 434 N(b)N(b)a Dx→yDx→y 2 N(j)N(j)i Dx→yDx→y 2 N(h)N(h)i Dx→yDx→y 3 N(g)N(g)def Dx→yDx→y 433 N(f)N(f)deg Dx→yDx→y 441 N(e)N(e)dfg Dx→yDx→y 121 N(d)N(d)acefg Dx→yDx→y 41322 Second round exchanged

21. Page: 21 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43 N(i)N(i)cjh Dx→yDx→y 241 N(a)N(a)cbd Dx→yDx→y 242 N(c)N(c)adi Dx→yDx→y 434 N(b)N(b)a Dx→yDx→y 2 N(j)N(j)i Dx→yDx→y 2 N(h)N(h)i Dx→yDx→y 3 N(g)N(g)def Dx→yDx→y 433 N(f)N(f)deg Dx→yDx→y 441 N(e)N(e)dfg Dx→yDx→y 121 N(d)N(d)acefg Dx→yDx→y 41322 Second round exchanged

22. Page: 22 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding e e b b h h i i j j f f d d c c g g a a 12 43

23. Page: 23 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding Link Weight Given a network G =(V,E), weight(u 1,v 1 ) ＜ weight(u 2,v 2 ) if and only if: (1) min(ID(u 1 ), ID(v 1 )) ＜ min(ID(u 2 ), ID(v 2 )) (2) min(ID(u 1 ), ID(v 1 )) ＝ min(ID(u 2 ), ID(v 2 )) and max(ID(u 1 ), ID(v 1 )) ＜ max(ID(u 2 ), ID(v 2 )). Given a network G =(V,E), weight(u 1,v 1 ) ＜ weight(u 2,v 2 ) if and only if: (1) min(ID(u 1 ), ID(v 1 )) ＜ min(ID(u 2 ), ID(v 2 )) (2) min(ID(u 1 ), ID(v 1 )) ＝ min(ID(u 2 ), ID(v 2 )) and max(ID(u 1 ), ID(v 1 )) ＜ max(ID(u 2 ), ID(v 2 )). 2 2 3 3 1 1 2 2 1 1 3 3 2 1 ＞ 1 1 2 3 ＞

24. Page: 24 WMNL e e b b h h i i j j f f d d c c g g a a 12 43 Local Topology Information Maintenance Virtual Link Reduction Forwarding

25. Page: 25 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 ab dc Local Topology Information Maintenance Virtual Link Reduction Forwarding

26. Page: 26 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Algorithm1: VLR Rule at Each Node v 1 Based on N 2 (v), a node v computes the localized broadcasting tree T v = (V(N 2 (v)), E(T v )) by applying Prim’s algorithm. 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. 5 Return the reduced link set L v (Unreduced) = {(v,w)|w ∈ N(v) and Reduced(v,w)= false}. ab dc

27. Page: 27 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding 2 4 3 3 3 1 ab dc

28. Page: 28 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm1: VLR Rule at Each Node v 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. ab dc

29. Page: 29 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm2: VLR-Based Broadcasting (at Each Node v) 1Compute the reduced link set L v (Unreduced) based on the VLR rule. 2 If L v (Unreduced) = ∅, the broadcast packet is dropped. 3 Otherwise, v becomes a forward node, and F(v) = {d v→w | (v,w) ∈ L v (Unreduced)}. ab dc

30. Page: 30 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding F(1) ={b, d} 2 2 4 4 3 3 ab dc

31. Page: 31 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm1: VLR Rule at Each Node v 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. ab dc F(1) ={b, d}

32. Page: 32 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm1: VLR Rule at Each Node v 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. ab dc F(1) ={b, d}

33. Page: 33 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm1: VLR Rule at Each Node v 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. ab dc F(1) ={b, d} N(4)N(4)13567 dx→ydx→y dacbb N(1)N(1)324 Dx→yDx→y bdb

34. Page: 34 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm1: VLR Rule at Each Node v 2 Reduced(v,w)= true if (v,w)  E(T v ) = ∅. 3 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is a neighbor of a known forward node u and is within one of u’s forward directions. 4 Reduced(v,w)= true if (v,w) ∈ E(T v ) and if w is the parent of v. ab dc F(1) ={b, d}

35. Page: 35 WMNL 5 5 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} 2 2

36. Page: 36 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d}

37. Page: 37 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d}

38. Page: 38 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} Algorithm2: VLR-Based Broadcasting (at Each Node v) 1Compute the reduced link set L v (Unreduced) based on the VLR rule. 2 If L v (Unreduced) = ∅, the broadcast packet is dropped. 3 Otherwise, v becomes a forward node, and F(v) = {d v→w | (v,w) ∈ L v (Unreduced)}.

39. Page: 39 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} 2 2 4 4 3 3 F(3) ={b} F(4) ={a, d} 9 9 5 5 6 6 7 7

40. Page: 40 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} F(3) ={b} F(4) ={a, d} 5 5 6 6 7 7

41. Page: 41 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} F(3) ={b} F(4) ={a, d} 8 8 10 F(9) ={b, c}

42. Page: 42 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} F(3) ={b} F(4) ={a, d} F(9) ={b, c}

43. Page: 43 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc F(1) ={b, d} F(3) ={b} F(4) ={a, d} F(9) ={b, c}

44. Page: 44 WMNL 5 5 2 2 8 8 9 9 10 6 6 4 4 3 3 7 7 1 1 Local Topology Information Maintenance Virtual Link Reduction Forwarding ab dc Further conserve energy

45. Page: 45 WMNL v uw 1 2 3 4 5

46. Page: 46 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm3: Adjust Angle of the Directional Antenna 1 Reduce the angle of one directional antenna by m degrees. The new angle of the antenna should not be smaller than a predefined threshold (minimal_angle). 2 After the angle reduction, compare the number of nodes covered by the new angle with that by the old angle. If the new number is the same as the old number, go to step 1. If the new number is smaller than the old number, use the old angle, and go to step 3. 3 Return the modified angle of the directional antenna.

47. Page: 47 WMNL Local Topology Information Maintenance Virtual Link Reduction Forwarding Algorithm3: Adjust Angle of the Directional Antenna minimal_angle = 20  m = 20  minimal_angle = 20  m = 20  90  70  50  30  10  30  b b c c a a Further conserve energy The number of nodes covered by the new angle should not be smaller than the old number. The new angle should not be smaller than minimal_angle. Use the old angle

48. Page: 48 WMNL Simulation Parameters Simulator ds (Wireless Routing Simulation Suite) － Considers only functions in the network layer － Assuming an ideal MAC layer without contention, collision, or node mobility Size of network 1000  1000m 2 Number of nodes30~160 Deployment Communication range250 m Antenna pattern K-sector (4  K  360) Simulation times

49. Page: 49 WMNL Performance metrics Transmission cost |F| Redundancy ratio Impact factor Number of nodes (30 ~ 160nodes) Number of sectors (1 ~ 130) 12 43 A(i)=90 N(i, v)=3 | F(v) |=3 The total number copies of a packet received by all nodes The total number of nodes in the network The total number copies of a packet received by all nodes The total number of nodes in the network

50. Page: 50 WMNL Comparison DSP “Broadcasting in ad hoc networks based on self-pruning” IEEE INFOCOM 2003 Omnidirectional Self-Pruning (OSP) “Efficient broadcasting in ad hoc wireless networks using directional antennas” IEEE TPDS 2006

51. Page: 51 WMNL VLR vs. DSP Normalized Transmission CostRedundancy Ratio DSP VLR K=4 K=8 K=16 K=32 K=360

52. Page: 52 WMNL VLR vs. OSP and Blind flooding Normalized Transmission CostRedundancy Ratio OSP VLR, K=8 Blind Flooding OSP VLR, K=8 Blind Flooding

53. Page: 53 WMNL Transmission Cost for different values of c 100 nodes80 nodes60 nodes

54. Page: 54 WMNL Transmission Cost for different values of c 100 nodes80 nodes60 nodes

55. Page: 55 WMNL Transmission Cost for different values of c 100 nodes80 nodes60 nodes

56. Page: 56 WMNL Transmission Cost for different values of c 100 nodes80 nodes60 nodes

57. Page: 57 WMNL Redundancy ratio for different network size 8 sectors, 100 nodes

58. Page: 58 WMNL The number of forward directions for different network size 8 sectors, 100 nodes

59. Page: 59 WMNL Transmission cost by applying the angle adjustment algorithm 1000  1000m 2, 100 nodes

60. Page: 60 WMNL This paper proposed a novel and efficient broadcasting algorithm (VLR) in ad hoc networks using directional antennas. –Achieving full delivery –Much lower transmission cost and redundancy –Conserves bandwidth and energy consumption –Neither location nor AOA information is needed

61. Page: 61 WMNL Wireless & Mobile Network Laboratory (WMNL.) Department of Computer Science and Information Engineering, Tamkang University