Copyright © 2011, 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

Copyright © 2011, Outline Introduction Background Design approach Simulation and discussion Conclusion References 2

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, Introduction 6

Copyright © 2011, 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

Copyright © 2011, Introduction 8

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, Introduction 13

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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, Background 21

Copyright © 2011, Background FMO type[9] 22

Copyright © 2011, 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

Copyright © 2011, 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

Copyright © 2011, Design approach – RBMR 25

Copyright © 2011, 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

Copyright © 2011, RBMR – Video encoding stage 27

Copyright © 2011, RBMR – Route discovery stage 28

Copyright © 2011, RBMR – Route discovery stage 29

Copyright © 2011, RBMR – Route discovery stage Block ID recorded in the RREQ header 30

Copyright © 2011, RBMR – Route discovery stage RREP is sent by the reverse block ID 31

Copyright © 2011, 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

Copyright © 2011, RBMR – Data transfer stage 33

Copyright © 2011, 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

Copyright © 2011, 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

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

Copyright © 2011, Simulation and discussion (cont.) Simulation settings for NS2 [11] 37 ParameterValue Transmission range250 m MAC ProtocolIEEE 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

Copyright © 2011, 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

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

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

Copyright © 2011, 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

Copyright © 2011, References 1) H. Hartenstein and K. P. Laberteaux, "A tutorial survey on vehicular ad hoc networks," Communications Magazine, IEEE, vol. 46, pp , )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, )S. Wenger, “H2.46/AVC over IP,” IEEE Trans. on Circuits and Syst. for Video Technol., vol. 13, no. 7, pp , )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, WIMOB IEEE, 2009, pp )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 )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, nd IFIP, )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 )F. Soldo, C. Casetti, C.-F. Chiasserini, P. Chaparro, “Streaming Media Distribution in VANETs,” in Proc, Global Telecommunications Conference, pp. 1-6,

Copyright © 2011, 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 , )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 , )“The network simulator (NS2),” [Online]. Available: 43