Road-Based Multipath Routing in 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
Outline • Introduction • Related work • Background • Design approach • Simulation and discussion • Conclusion • References
Introduction • Vehicular Ad Hoc Networks (VANETs) consists of mobile nodes, and each node moves arbitrarily and communicates with others by multiple wireless links. • Wireless links would be broken frequently because of high mobility in VANET. • In urban VANET , each vehicle moves in constrained areas independently.
Introduction Ad-hoc on-demand distance vector(AODV)  and dynamic source routing(DSR)  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.
Introduction Node-centric problem .
Introduction One alternative approach is offered by geographical routing protocols, e.g., greedy–face–greedy (GFG) , greedy other adaptive face routing (GOAFR) . It can not always find the route to destination.
Introduction Geographical routing problem .
Introduction  proposed road-based VANET routing protocol that leverage real-time vehicular traffic information to create path. There are many single path routings, which need to create a new route when a path breaks.
Introduction Multipath routing creates many paths from sender to receiver. If one route disconnects, sender can choose other routes to transfer.  has proofed multiple path can improve the packet delivery ratio if there is no interference.
Introduction Multiple path can classify two types : node-disjoint and link-disjoint .
Introduction (a) Node-disjoint and (b) link-disjoint.
Introduction  has proofed node-disjoint is better than link-disjoint on packet delivery ratio.
Introduction • We propose a road-based multipath routing(RBMR) which is node-disjoint. • Improve the reliability of routing paths • Maintain a modified vehicle persistence score (VPS)  to determine the stability of a node
Related work On-demand multipath distance vector routing (AOMDV)  creates several paths from source to destination, and packets are sent after paths established.
Related work AOMDV has a “route cutoff” problem, which means some reverse paths would be ignored .
Related work  tries to solve route cutoff problem, But it transfers packets after all paths are created.
Related work  is a node-disjoint multipath routing. It sends packets after creating one path. but it is node-centric routing protocol, so the route is easy to disconnect than road-based routing protocol.
Background • Modified vehicle persistence score (VPS) • VPS table • VPS table entry<ID, position, road segment, direction, VPS>  • ID: the neighbor’s identifier • position: the GPS coordinate (x, y), which stands for the neighbor’s position • road segment : the neighbor is located • direction: the neighbor’s moving direction • VPS: the value used to select relay node
Background • VPS maintains • When node received a HELLO message , it searched its VPS table. • If the neighbor’s ID can be found in the VPS table, the node increasesneighbor's VPS by 1. • If identifier can not be found in the VPS table, the node adds the neighbor’s information to the VPS table, and initializes the node’s VPS to 1.
Background (a) VPS values are initialized when receiving a HELLO message (b) VPS values are increased when receiving a HELLO message An example of VPS table
Design approach - RBMR • Two stages of the proposed road-based multipath routing (RBMR) • Route discovery stage • Data transfer stage
RBMR – Route discovery stage How Relay node handles RREQ
RBMR – Route discovery stage RREQ packet transfers.
RBMR – Route discovery stage Road segment ID recorded in the RREQ header.
RBMR – Route discovery stage RREP returned through the reverse road segment IDs.
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  • 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 relay node which has the highest.
RBMR – Data transfer stage Relay node is selected by VPS.
Simulation and discussion Packet delivery ratio: the number of data packets received at receiver divided by the number of data packets generated at sender.
Simulation and discussion Routing overhead: when transferring a packet, how many control messages need to send.
Simulation and discussion Simulation settings for NS2 
Simulation and discussion Simulation settings for VanetMobiSim 
Simulation and discussion Delivery ratio under different numbers of nodes
Simulation and discussion Routing overhead under different numbers of nodes
Conclusion We propose road-based multipath routing for Urban VANETs. The proposed RBMR improves the delivery ratio by9% and control overhead by 30% compared with AOMDV and NDMR. Simulation results show that the proposed RBMR performs well in city environments.
References • 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. • D. B. Johnson and D. A. Maltz, “Dynamic source routing in ad hoc wireless networks,” Mobile Comput., vol. 353, no. 5, pp. 153–161, 1996. • JosianeNzouonta, NeerajRajgure, Guiling (Grace) Wang, “VANET Routing on City Roads Using Real-Time Vehicular Traffic Information,” IEEE Transactions on Vehicular Technology, pp. 3609-3626, 2009. • P. Bose, P. Morin, I. Stojmenovic, and J. Urrutia, “Routing with guaranteed delivery in ad hoc wireless networks,” ACM Wirel. Netw., vol. 7, no. 6, pp. 609–616, Nov. 2001. • 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. • XiaoxiaHuang, 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. • 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.
References • 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. • 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. • Bo Xue, Pinyi Ren, Shuangcheng Yan ,“Link Optimization Ad-hoc On-Demand Multipath Distance Vector Routing for Mobile Ad-hoc Networks,” in Proc. International Conference on Wireless Communications, Networking and Mobile Computing, pp 1-6,2009. • 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. • 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. • “The network simulator (NS2),” [Online]. Available: http://www.isi.edu/nsnam/ns/. • 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.