1. Copyright © 2012, MBL@CS.NCTU Road-Based Multipath Routing in Urban VANETs 都會區車輛隨意網路之多重路徑繞徑技術 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 © 2012, MBL@CS.NCTU Outline Introduction Related work Background Proposed road-based multipath routing Simulation and discussion Conclusion and Future work References 2

3. Copyright © 2012, MBL@CS.NCTU Introduction Vehicular Ad Hoc Networks (VANETs) consist of mobile vehicles (nodes), and each node moves arbitrarily and communicates with others by wireless links Wireless links would be broken frequently because of high mobility in VANETs In urban VANETs, each node moves in constrained areas independently 3

4. Copyright © 2012, 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 protocols which are node-centric The traditional node-centric view of the route leads to frequent broken routes in the presence of VANETs’ high mobility [3] 4

5. Copyright © 2012, MBL@CS.NCTU Introduction 5 Node-centric problem [3]

6. Copyright © 2012, MBL@CS.NCTU Introduction One alternative approach, geographical routing, is offered by geographical routing protocols, e.g., greedy– face–greedy (GFG) [4] and greedy other adaptive face routing (GOAFR) [5] Since dead end roads exist in Urban VANETs, geographical routing protocols do not always perform well 6

7. Copyright © 2012, MBL@CS.NCTU Introduction Geographical routing problem [3] 7

8. Copyright © 2012, MBL@CS.NCTU Introduction RBVT [3] proposed a road-based VANET routing protocol that leverages real-time vehicular traffic information to create road-based routing paths There are many single path routing protocols, which need to create a new route when a path breaks 8

9. Copyright © 2012, MBL@CS.NCTU Introduction Multipath routing creates many paths from sender to receiver If one route disconnects, sender can choose other routes to transfer packets Multipath routing can classify two types : node-disjoint routing and link-disjoint routing [6] 9

10. Copyright © 2012, MBL@CS.NCTU Introduction Node-disjoint routes (a) and link-disjoint routes (b) 10

11. Copyright © 2012, MBL@CS.NCTU Introduction In [7], the authors have proved node-disjoint multipath routing is better than link-disjoint multipath routing in terms of packet delivery ratio We propose a road-based multipath routing (RBMR), which is node-disjoint 11

12. Copyright © 2012, MBL@CS.NCTU Introduction We propose a road-based multipath routing (RBMR), which is node-disjoint –It focuses on establishing two fast routes from sender to receiver –It begins to send packets once a fast route is established –The slow route which is established later will be used if the first route is disconnected –To the best of our knowledge, there is no existing road-based multipath routing protocol 12

13. Copyright © 2012, MBL@CS.NCTU Related work Connectionless approach (CLA) [8] is a road-based single path routing protocol It records road segments instead of nodes Ad-hoc on-demand multipath distance vector routing (AOMDV) [9], which is link-disjoint, creates several paths from source to destination, and packets are sent after paths established 13

14. Copyright © 2012, MBL@CS.NCTU Related work NDMR [10] is a node-centric, node-disjoint multipath routing –It sends packets after creating one path, but it is a node-centric routing protocol, so the route is easy to be disconnected than that of the road-based routing protocol 14

15. Copyright © 2012, MBL@CS.NCTU Related work Routing method CLA [8] AOMDV [9] NDMR [10] RBMR (proposed) Path counts 1 ≧2≧2 2 2 Node- centric or Road-based Road- based Node- centric Road- based Node- disjoint or Link- disjoint - ( Single path routing ) Link- disjoint Node- disjoint Node- disjoint Obstacles considered YesNo Yes 15

16. Copyright © 2012, MBL@CS.NCTU Background Vehicle moving similarity [11] –Select neighbor nodes which have similar speeds with the sender as relay nodes –Vehicle moving similarity is reflected by Vehicle persistence score (VPS) 16

17. Copyright © 2012, MBL@CS.NCTU Background Vehicle persistence score (VPS) –VPS table entry [12] –ID: the neighbor’s identifier –position: the GPS coordinate (x, y), which stands for the neighbor’s position –road segment : where the neighbor is located –direction: the neighbor’s moving direction –VPS: the value used to reflect the neighbor’s stability 17

18. Copyright © 2012, MBL@CS.NCTU Background VPS maintains –When a node received a HELLO message from a neighbor, it searched its VPS table –If the neighbor’s ID can be found in the VPS table, the node increases the neighbor's VPS by 1 –If the neighbor’s ID can not be found in the VPS table, the node adds the neighbor’s information ( ID, position, road segment, direction, and VPS) to the VPS table, and initializes the node’s VPS to 1 18

19. Copyright © 2012, MBL@CS.NCTU Background An example of VPS table [11] (a) VPS values are initialized when receiving a HELLO message (b) VPS values are increased when receiving a HELLO message 19

20. Copyright © 2012, MBL@CS.NCTU Design approach - RBMR Two stages of the proposed road-based multipath routing (RBMR) –Route discovery stage –Data transfer stage 20

21. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage How a relay node handles RREQ 21

22. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage RREQ packet transfer 22 Steps: 1. S sends RREQ to A and C 2. C sends RREQ to A 3. A discards RREQ which gets from C 4. A sends RREQ to B and E 5. E sends RREQ to D 6. B sends RREQ to F and D 7. D discards RREQ which gets from B 8. F sends RREQ to D

23. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage Road segment ID recorded in the RREQ header 23

24. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage First, PATH1 is established from sender to receiver Second, PATH2 is established Third, PATH3 is established PATH2 will be discarded at receiver because the road segment A8 has been used 24

25. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage RREP returned PATH1 and PATH3 through the reverse road segment IDs 25

26. Copyright © 2012, MBL@CS.NCTU RBMR – Route discovery stage RBMR will send packets although only PATH1 is established PATH3 will be established later, and it will be used if PATH1 is disconnected 26

27. Copyright © 2012, 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 [12] road segment: used to choose relay nodes which located in the next road segment of the header direction : used to choose relay nodes which moved toward the receiver VPS: used to choose a relay node which has the highest score 27

28. Copyright © 2012, MBL@CS.NCTU RBMR – Data transfer stage Relay node is selected by VPS 28

29. Copyright © 2012, MBL@CS.NCTU Simulation and discussion Packet delivery ratio: the number of data packets received at the receiver divided by the number of data packets generated at the sender [11] Control overhead: when transferring a packet, how many control packets (including RREQ, RREP, RRER) need to send [11] End-to-end delay: the time taken for a packet to be transmitted (including RREQ, RREP) from sender to receiver [8] 29

30. Copyright © 2012, MBL@CS.NCTU Simulation and discussion Simulation settings [13][14] 30 ParameterValue Transmission range376 m MAC ProtocolIEEE 802.11p Network area1000 m x 1000 m Simulation time600 s Number of nodes30, 40, 50, 60, 70 Connection typeCBR Packet size512bytes Mobility modelVanetMobiSim Sender and receiver pairs10 Packet sending rate10 packet/sec Max. traffic lights10 Min. Speed8 m/s Max. Speed17 m/s Max. acceleration0.6 m/s 2 Normal deceleration0.5 m/s 2

31. Copyright © 2012, MBL@CS.NCTU Simulation and discussion Delivery ratio under different numbers of nodes 31

32. Copyright © 2012, MBL@CS.NCTU Simulation and discussion 32 Control overhead under different numbers of nodes

33. Copyright © 2012, MBL@CS.NCTU Simulation and discussion End-to-end delay under different numbers of nodes 33

34. Copyright © 2012, MBL@CS.NCTU Conclusion and Future Work We propose a road-based multipath routing (RBMR) protocol for Urban VANETs The proposed RBMR improves the delivery ratio by 9% 6%, and 15%, control overhead by 30%, 25%, and 19%, and end-to-end delay by 28%, 11%, and 7% compared with AOMDV, NDMR, and CLA, respectively Simulation results show that the proposed RBMR performs well on packet transferring in city environments than road-based single path and node-centric multipath routing protocols. 34

35. Copyright © 2012, MBL@CS.NCTU Conclusion and Future Work Create over two node-disjoint paths and select the most reliable path to transfer packets 35

36. Copyright © 2012, MBL@CS.NCTU References [1] C. E. Perkins and E. M. Royer, “Ad hoc on-demand distance vector routing,” in Proc. 2nd IEEE Workshop Mobile Comput. Syst. Appl., New Orleans, LA, Feb. 1999, pp. 90–100. [2] D. B. Johnson and D. A. Maltz, “Dynamic source routing in ad hoc wireless networks,” in Proc. Mobile Comput., vol. 353, no. 5, pp. 153–161, 1996. [3] Josiane Nzouonta, Neeraj Rajgure, Guiling (Grace) Wang, “VANET Routing on City Roads Using Real-Time Vehicular Traffic Information,” in Proc. IEEE Transactions on Vehicular Technology, pp. 3609-3626, 2009. [4] P. Bose, P. Morin, I. Stojmenovic, and J. Urrutia, “Routing with guaranteed delivery in ad hoc wireless networks,” in Proc. ACM Wirel. Netw., vol. 7, no. 6, pp. 609–616, Nov. 2001. [5] F. Kuhn, R. Wattenhofer, Y. Zhang, and A. Zollinger, “Geometric ad hoc routing: Of theory and practice,” in Proc. 22nd Annu. Symp. Principles Distrib. Comput., Boston, MA, Jul. 2003, pp. 63–72. [6] Xuefei Li; Cuthbert L, ”On-demand Node-Disjoint Multipath Routing in Wireless Ad hoc Networks,” in Proc. IEEE International Conference on Local Computer Networks, pp 419-420, 2004. [7] Xiaoxia Huang, Yuguang Fang,“ Performance Study of Node-Disjoint Multipath Routing in Vehicular Ad Hoc Networks”, in Proc. IEEE Transactions on Vehicular Technology, pp 1942-1950, 2009. [8] Y. H. Ho, A. H. Ho, and K. A. Hua, “Routing Protocols for Inter-Vehicular Networks: A Comparative Study in High-Mobility and Large Obstacles Environments, ” Computer Communications Journal - Special Issue on Mobility Protocols for ITS/VANET, 2008. [9] Mahesh K. Marina, Sami R. Das,”On-demand Multipath Distance Vector Routing in Ad Hoc Networks”, in Proc. Ninth International Conference on Network Protocols, pp 14-23, 2001. [10]Chang-Woo Ahn, “ A Node-Disjoint Multipath Routing Protocol Based on AODV in Mobile Ad Hoc Networks”, in proc. Seventh International Conference on Information Technology, pp828-833,2010. 36

37. Copyright © 2012, MBL@CS.NCTU References [11] Min Hsuan, Kuochen Wang,” A reliable routing scheme based on vehicle moving similarity for VANETs”, in Proc. IEEE Region 10 Conference on TENCON, pp 426-430,2011. [12] H.-F. Ho, K.C. Wang, Y.-L. Hsieh, “Resilient Video Streaming for Urban VANETs,” in Proceedings of the Seventh Workshop on Wireless Ad Hoc and Sensor Networks, 2011. [13] “The network simulator (NS2),” [Online]. Available: http://www.isi.edu/nsnam/ns/. [14] M. Fiore, J. Härri, F. Filali, and C. Bonnet, “Vehicular mobility simulation for VANETs,” in Proc. 40th Annual Simulation Symp., Mar. 2007, pp. 301-307. 37