A Multicast Routing Scheme for EfIcient Safety Message Dissemination in VANET

1. A Multicast Routing Scheme for EfIcientSafetyMessage Dissemination in VANET 指導教授：郭文興 學生：林詠軒

2. Abstract • VANET provide communication between vehicles. • CCWS is one of the safety applications in VANET • Provide a more efficient multicast routing scheme • Reduce unnecessary transmissions in adaptive transmission range • Make routing problem into minimum Steiner tree problem • Support various traffic conditions • Optimize the wireless channel utilization • Prioritize the receivers

3. Index Abstract I、 Introduction II、 Related work • Cooperative collision warning system • Interaction graph model • Delay-constrained minimum Steiner tree III、 Problem formulation

4. Index IV、 Obtaining inputs, parameters and functions using context information • Network modeling • Cost function • Delay function • Identifying the sender node • Identifying receiver nodes • Determining the delay constraint at each receiver node V、 Discussion VI、 Conclusion and future work Acknowledgment References

5. Introduction • VANET • V2V and V2I are standardize in IEEE 802.11p and are proposed in Wireless Access in Vehicular Environments (WAVE) • CCWS is one of applications in VANET • There are many conceptions and prototypes had been developed in prior research

6. Introduction • Routine and event safety messages can be utilized • Routine safety messages aka beacon messages • Event safety messages aka warning messages • Beacon： • Contain information such as position and speed • Provide advance warning of any possible collision • Warning messages： • Triggered by drastic change in vehicle state

7. Introduction • Abnormal vehicles • May endanger other vehicles • Sent warning messages to all endangered vehicles • Message propagation • Beyond the coverage area of original sender • Use multi-hop scheme • Transmit information by step node (different from host-client) • Timely dissemination can prevent multi-vehicle chain collision

8. Introduction Fig1: Illustration of multi-hop routing for warning messages

9. Introduction • Efficient safety communication protocols • Reduce channel-load • Reference [5] [7] [8] [9] • Reduce retransmissions • Don’t considerate the usage of beacon • No prior knowledge on receivers • Rebroadcast rules • Detect if others sent the same message

10. Introduction-solution • Send messages to relevant vehicles • Make problem into a well-known delay-constrained minimum Steiner tree (D-CMST) • Steiner tree • Reduce the length of the spanning tree • Can solve problem by existing algorithms • To find the sender node, endanger vehicles, life time of messages by beaconsfrom CCWS

11. Related work-CCWS • Including some apps • Forward collision warning • Lane change assistant • Intersection warning • Other depend on the situation awareness capability • Use at least one IEEE 802.11p DSRC/WAVE wireless device • Use an omni-directional antenna as cost-feasible option • State data • GPS, estimator and in-vehicle sensors

12. Related work-Interaction graph model • Regular condition • In highway traffic • All vehicles are: • Inside a region behind the sender • Behind the sender with same direction • Inside a predefined risk zone

13. Related work-Interaction graph model • From reference[11] • New solution: • Interact in a specific region and at a specific time

14. Interactive graph model • 𝓖(𝓥,𝓔) • 𝓥 represents vehicles • 𝓔 ⊆{<𝓋i,𝓋j>:𝓋i, 𝓋j ∈𝓥,𝓋i≠ 𝓋j} • Construct graph 𝓖 by vehicles 𝓥 with empty edges • Calculate the edge and added into the graph

15. Interactive graph model • Calculate the possibility of collision between two vehicles • Compare the distance to the collision position • Estimate the distance vehicle required to stop • 3 distinct cases • Following • Opposite • intersects

16. Delay-constrained minimum Steiner tree • Steiner tree also called least-cost multicast routing problem • Use near-optimal solution rather than optimal solution by heuristic • Heuristic is various

17. Problem formulation • Improve the use of channel • Reduce unnecessary transmission • Minimize the transmission range • e = <u,v>∈E • δ(v): V→R • delay • Δ(v): V→R • Delay constraint • R⊆V-{s} • receivers • V \ ( R ⋃ { s } ) • relay nodes

18. Problem formulation

19. Determining the delay constraint at each receiver node

20. Determining the delay constraint at each receiver node

21. Discussions • Existing D-CMST algorithms not designed for multicast routing • Need more modifications • Advantages • Applicability is various • Optimization of the wireless channel • Prioritization of the receivers

22. Conclusion and future work • Performance evaluation • Network simulator • Complete communication protocol • Reliability • Message encoding • Multiple sender • Transmission scheduling • Multichannel operation

23. References • [1] D. Jiang and L. Delgrossi, “IEEE 802.11p: Towards an international standard for wireless access in vehicular environments,” in Proc. of the IEEE Vehicular Technology Conference. IEEE, 2008, pp. 2036–2040. • [2] R. Sengupta, S. Rezaei, S. E. Shladover, D. Cody, S. Dickey, and H. Krishnan, “Cooperative collision warning systems: Concept definition and experimental implementation,” Journal of Intelligent Transportation Systems, vol. 11, no. 3, pp. 143 – 155, 2007. • [3] H.-S. Tan and J. Huang, “DGPS-based vehicle-to-vehicle cooperative collision warning: Engineering feasibility viewpoints,” IEEE Transac- tions on Intelligent Transportation Systems, vol. 7, no. 4, pp. 415–428, 2006. • [4] D. Jiang, V. Taliwal, A. Meier, W. Holfelder, and R. Herrtwich, “Design of 5.9 ghz DSRC-based vehicular safety communication,” IEEE Wireless Communications, vol. 13, no. 5, pp. 36–43, 2006. • [5] S. Biswas, R. Tatchikou, and F. Dion, “Vehicle-to-vehicle wireless communication protocols for enhancing highway traffic safety,” IEEE Communications Magazine, vol. 44, no. 1, pp. 74–82, 2006. • [6] S. Eichler, “Performance evaluation of the IEEE 802.11p WAVE com- munication standard,” in Proc. of the 66th IEEE Vehicular Technology Conference, 2007-Fall, pp. 2199–2203. • [7] E. Fasolo, A. Zanella, and M. Zorzi, “An effective broadcast scheme for alert message propagation in vehicular ad hoc networks,” in Proc. of the IEEE International Conference on Communications (ICC), vol. 9, 2006, pp. 3960–3965.

24. References • [8] Y.-T. Yang and L.-D. Chou, “Position-based adaptive broadcast for inter- vehicle communications,” in Proc. of the IEEE International Conference on Communications (ICC), 2008, pp. 410–414. • [9] S. Yu, M. Lee, and G. Cho, “An emergency message propagation method in highway traffic,” in Ubiquitous Computing Systems, ser. LNCS. Springer Berlin / Heidelberg, 2006, pp. 331–343. • [10] A. Boukerche, H. A. B. F. Oliveira, E. F. Nakamura, and A. A. F. Loureiro, “Vehicular ad hoc networks: A new challenge for localization- based systems,” Computer Communications, vol. 31, no. 12, pp. 2838– 2849, 2008. • [11] A. Sebastian, M. Tang, Y. Feng, and M. Looi, “Multi-vehicles interaction graph model for cooperative collision warning system,” in Proc. of the IEEE Intelligent Vehicles Symposium. Xi’an, China: IEEE, 2009. • [12] F. K. Hwang and D. S. Richards, “Steiner treeproblems,” Networks, vol. 22, no. 1, pp. 55–89, 1992. • [13] V. P. Kompella, J. C. Pasquale, and G. C. Polyzos, “Multicast routing for multimedia communication,” IEEE/ACM Transactions on Networking, vol. 1, no. 3, pp. 286–292, 1993. • [14] M. Parsa, Q. Zhu, and J. J. Garcia-Luna-Aceves, “An iterative algorithm for delay-constrained minimum-cost multicasting,” IEEE/ACM Transac- tions on Networking, vol. 6, no. 4, pp. 461–474, 1998. • [15] H. F. Salama, D. S. Reeves, and Y. Viniotis, “Evaluation of mul- ticast routing algorithms for real-time communication on high-speed networks,” IEEE Journal on Selected Areas in Communications, vol. 15, no. 3, pp. 332–345, 1997. • [16] X. Wang, J. Cao, H. Cheng, and M. Huang, “QoS multicast routing for multimedia group communications using intelligent computational methods,” Computer Communications, vol. 29, no. 12, pp. 2217–2229, 2006. • [17] A. Munaretto and M. Fonseca, “Routing and quality of service support for mobile ad hoc networks,” Computer Networks, vol. 51, no. 11, pp. 3142–3156, 2007.

25. Problem • Relay node • How to decrease coverage area • Channel using efficiency

26. NS2 簡介 • Ns 主程式 • 進行以tcl為語言的設定檔的模擬程序 • Tcl script • 描述模擬中所有變數 • 模擬結果 • Nam 可播放模擬動畫 • Tr模擬結果數據

27. NS2 簡介 • 分析數據工具：awk • 字串處理程式 • 程式碼類似C語言 • 可以與shell互動 • 逐行處理輸入之格式化資料 • 可將結果存至檔案

28. NS2簡介 • 呈現結果-gnuplot • 先使用awk取出需要的資訊（如座標） • 可將座標圖存成gif