1. Copyright © 2011, MBL@CS.NCTU Road-Based Multipath Routing With Resilient Video Streaming for Urban VANETs 指導教授：王國禎 博士 學生：鍾昆佑 國立交通大學網路工程研究所 行動計算與寬頻網路實驗室 1

2. Copyright © 2011, MBL@CS.NCTU Outline Introduction Background Design approach Simulation and discussion Conclusion References 2

3. Copyright © 2011, MBL@CS.NCTU Introduction It is commonly acknowledged that Vehicular Ad Hoc Networks (VANETs) are unsuited to support multimedia traffic. Wireless links would be broken frequently because of high mobility in VANET. 3

4. Copyright © 2011, MBL@CS.NCTU Introduction In urban VANET, each vehicle moves in constrained areas independently. Due to the error-prone characteristic of wireless communication, routing packets over multiple hops results in packet loss and causes poor quality of reconstructed video at the receiver 4

5. Copyright © 2011, MBL@CS.NCTU Introduction Ad-hoc on-demand distance vector(AODV) [1] and dynamic source routing(DSR) [2] are two most widely studied on-demand ad hoc routing protocol The traditional node-centric view of the route leads to frequent broken routes in the presence of VANETs’ high mobility as illustrated in Figure 1 [3] 5

6. Copyright © 2011, MBL@CS.NCTU Introduction 6

7. Copyright © 2011, MBL@CS.NCTU Introduction One alternative approach is offered by geographical routing protocols, e.g., greedy–face–greedy (GFG) [4], greedy other adaptive face routing (GOAFR) [5] It can not always find the route to destination as illustrated in Figure 2 7

8. Copyright © 2011, MBL@CS.NCTU Introduction 8

9. Copyright © 2011, MBL@CS.NCTU Introduction There are many single path routings, which need new route discovery whenever a path breaks [6] has proofed multiple path can improve the packet delivery ratio if there is no interference. 9

10. Copyright © 2011, MBL@CS.NCTU Introduction PA and PB are packet delivery ratio without interference for each single path P sin : Single path routing delivery ratio P multi : Multiple path routing delivery ratio 10

11. Copyright © 2011, MBL@CS.NCTU Introduction P sin =Max{PA,PB} (1) P multi =1-(1-PA)(1-PB)=PA+PB-PAPB (2) PA ≤ 1 and PB ≤ 1, PAPB ≤ Min{PA,PB} (3) P multi ≥ Max{PA,PB} ≥ P sin (4) 11

12. Copyright © 2011, MBL@CS.NCTU Introduction Multiple path can classify two types : node-disjoint and link-disjoint [7] has proofed node-disjoint is better than link-disjoint on packet delivery ratio 12

13. Copyright © 2011, MBL@CS.NCTU Introduction 13

14. Copyright © 2011, MBL@CS.NCTU Introduction p ： probability of route broken P i ： number of i common node Path1 has m nodes and Path2 has n nodes 14

15. Copyright © 2011, MBL@CS.NCTU Introduction P 0 =p[Path1] x p[Path2]=(1-(1-p) m ) x (1-(1-p) n ) (4) P 1 =p[Path1] x p[Path2]=(1-(1-p) m-1 ) x (1-(1-p) n-1 )+p (5) Because P 1 - P 0 ≥ 0, so we can prove P k ≥ P k-1 ≥ … ≥ P 0 by mathematical induction 15

16. Copyright © 2011, MBL@CS.NCTU Introduction We propose a road-based multipath routing(RBMR) with resilient video streaming scheme that integrates flexible macroblock ordering (FMO) and multiple description coding (MDC) —Improve video streaming quality —Recover lost packets with error resilience via FMO and MDC —Improve the reliability of routing paths —Maintain a modified vehicle persistence score (VPS) [8] to determine the stability of a node 16

17. Copyright © 2011, MBL@CS.NCTU Background Modified vehicle persistence score (VPS) –VPS table VPS table entry –ID: the neighbor’s identifier –position: the GPS coordinate (x, y), which stands for the neighbor’s position –segment : the neighbor is located –direction: the neighbor’s moving direction –VPS: the value used to select relay node 17

18. Copyright © 2011, MBL@CS.NCTU Background VPS maintains –When vehicle received a HELLO message, it searched its VPS table –If the neighbor’s ID can be found in the VPS table, the vehicle increases neighbor's VPS by 1. –If identifier can not be found in the VPS table, the vehicle adds the neighbor’s information to the VPS table, and initializes the neighbor’s VPS to 1. 18

19. Copyright © 2011, MBL@CS.NCTU Background An example of VPS table (a) VPS values are initialized when receiving a HELLO message (b) VPS values are increased when receiving a HELLO message 19

20. Copyright © 2011, MBL@CS.NCTU Background Flexible Macroblock Ordering (FMO) [9] –One of error resilience techniques defined by the H.264/AVC specifications –An image is divided into slice groups, and each slice group can be divided into several slices, consisting of a sequence of macroblocks that belong to the same slice group –The power of FMO depends on how the macroblocks are ordered 20

21. Copyright © 2011, MBL@CS.NCTU Background 21

22. Copyright © 2011, MBL@CS.NCTU Background FMO type[9] 22

23. Copyright © 2011, MBL@CS.NCTU Background Multiple description coding (MDC) segments a single stream into n substreams which called descriptions. MDC is used to supply error resilience to media streams. 23

24. Copyright © 2011, MBL@CS.NCTU Design approach - RBMR Four stages of the proposed road-based multipath routing (RBMR) scheme for resilient video streaming –Video encoding stage –Route discovery stage –Data transfer stage –Video decoding stage 24

25. Copyright © 2011, MBL@CS.NCTU Design approach – RBMR 25

26. Copyright © 2011, MBL@CS.NCTU RBMR – Video encoding stage Video encoding stage –Before a sender starts transmitting to a receiver, it encodes the row video stream with FMO type 1, splitting the video streaming into multiple slices for error resilience at the receiver 26

27. Copyright © 2011, MBL@CS.NCTU RBMR – Video encoding stage 27

28. Copyright © 2011, MBL@CS.NCTU RBMR – Route discovery stage 28

29. Copyright © 2011, MBL@CS.NCTU RBMR – Route discovery stage 29

30. Copyright © 2011, MBL@CS.NCTU RBMR – Route discovery stage Block ID recorded in the RREQ header 30

31. Copyright © 2011, MBL@CS.NCTU RBMR – Route discovery stage RREP is sent by the reverse block ID 31

32. Copyright © 2011, MBL@CS.NCTU RBMR – Data transfer stage Relay nodes selection –Select relay nodes from the VPS table according to the data stored in the VPS table –Data used for selection segment: used to choose relay nodes which located in the next segment of the header. direction : used to choose relay nodes which moved toward the receiver. VPS: used to choose relay node which has the highest. 32

33. Copyright © 2011, MBL@CS.NCTU RBMR – Data transfer stage 33

34. Copyright © 2011, MBL@CS.NCTU RBMR– Video decoding phase Video decoding phase –After a receiver receives all packets transmitting from a sender, it decodes and creates a reconstructed video stream 34

35. Copyright © 2011, MBL@CS.NCTU Simulation and discussion Packet delivery ratio: the number of data packets successfully delivered to the receiver divided by the total number of data packets generated by the sender 35

36. Copyright © 2011, MBL@CS.NCTU Simulation and discussion (cont.) Routing overhead : when we transfer a packet, how many control messages we need to send. 36

37. Copyright © 2011, MBL@CS.NCTU Simulation and discussion (cont.) Simulation settings for NS2 [11] 37 ParameterValue Transmission range250 m MAC ProtocolIEEE 802.11 Network area1000 m x 1000 m Lane width5 m Number of vehicles30, 40, 50, 60, 70 Connection typeCBR Packet size1000 bytes Mobility modelVanetMobiSim Simulation time100 s

38. Copyright © 2011, MBL@CS.NCTU Simulation and discussion (cont.) Simulation settings for VanetMobiSim [4, 5] 38 ParameterValue Terrain Dimension1000 m x 1000 m Max. traffic lights6 Time interval between traffic lights change 10 s Number of Lanes2 Nodes (vehicles)30, 40, 50, 60, 70 Min. Speed8.1m/s Max. Speed16.9 m/s Length of vehicle5 m Max. acceleration0.6 m/s 2 Normal deceleration0.5 m/s 2

39. Copyright © 2011, MBL@CS.NCTU Simulation and discussion (cont.) Delivery ratio under different numbers of vehicles 39

40. Copyright © 2011, MBL@CS.NCTU Simulation and discussion (cont.) 40 Routing overhead under different numbers of vehicles

41. Copyright © 2011, MBL@CS.NCTU Conclusion We propose road-based multipath routing for Urban VANETs The proposed RBMR improves the delivery ratio by 7% and control overhead by 30% compared with AOMDV Simulation results show that the proposed RBMR performs well in city environments 41

42. Copyright © 2011, MBL@CS.NCTU References 1) H. Hartenstein and K. P. Laberteaux, "A tutorial survey on vehicular ad hoc networks," Communications Magazine, IEEE, vol. 46, pp. 164-171, 2008. 2)M.H. Wei, K.C. Wang, and I.L. Hsieh “A reliable routing scheme based on vehicle moving similarity for VANETs,” in Proc. IEEE TENCON, 2011. 3)S. Wenger, “H2.46/AVC over IP,” IEEE Trans. on Circuits and Syst. for Video Technol., vol. 13, no. 7, pp. 645-656, 2003. 4)N. Qadri, M. Altaf, M. Fleury, M. Ghanbari, and H. Sammak, "Robust Video Streaming over an Urban VANET," in Proc, International Conference on Wireless and Mobile Computing, Networking and Communications, 2009. WIMOB 2009. IEEE, 2009, pp. 429- 434. 5)N. N. Qadri, M. Fleury, and M. Ghanbari, "Approaching P2P communication in a vehicular ad hoc network," in IEEE 34 th Conference on Local Computer Networks, pp. 695-701 2009. 6)N. Qadri, M. Fleury, M. Altaf, B. R. Rofoee, and M. Ghanbari, "Resilient P2P multimedia exchange in a VANET," in Wireless Days (WD), pp. 1-6, 2009 2nd IFIP, 2009. 7)N. N. Qadri, M. Fleury, M. Altaf, and M. Ghanbari, "Multi-source video streaming in a wireless vehicular ad hoc network," Communications, IET, vol. 4, pp. 1300-1311. 8)F. Soldo, C. Casetti, C.-F. Chiasserini, P. Chaparro, “Streaming Media Distribution in VANETs,” in Proc, Global Telecommunications Conference, pp. 1-6, 2008. 42

43. Copyright © 2011, MBL@CS.NCTU References 9)W. Shu, P. Wang, A. Guo, X. Wang, F. Liu, “Enhanced GPSR using Neighbor-Awareness position Update and Beacon-assist Geographic Forwarding in vehicular ad hoc networks,” in proc, Intelligent Vehicles Symposium, pp. 1143-1147, 2009 10)J. Nzouonta, N. Rajgure, A. Guiling Wang, C. Borcea, “VANET Routing on City Roads Using Real-Time Vehicular Traffic Information,” in Transactions Vehicular Technology pp. 3609 - 3626, 2009 11)“The network simulator (NS2),” [Online]. Available: http://www.isi.edu/nsnam/ns/. 43