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A Traffic-light-based Reliable Routing Protocol for Urban VANETs
都會區車載隨意網路下基於紅綠燈之可靠繞徑技術指導教授:王國禎 博士 學生:張景喬
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
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Outlines
• Introduction• Background• Related work• Proposed Traffic-Light based Approach routing protocol• Simulation results• Conclusion• References
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Introduction
• Vehicular ad hoc network is a high mobility wireless ad hoc network.
• Due to a high mobility in VANETs, wireless links would be disconnected frequently .
• Routing paths may be very unstable at high mobility wireless ad hoc network
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Introduction (cont.)
• Topology changed frequently.
• Broken link causes throughput decreases, and packet delay increases.
• Highway safety, commercial advertisement, and Digital entertainment becomes popular issue recently.
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Related work - DSR
• DSR (Dynamic Source Routing)• Cached routing information• Main process:
– Route discovery– Route maintenance
• Once node receives RREQ, if the node has not seen it before, it adds themselves to the route and forward them.
• If there is any broken link happens due to the network topology changes, source node can issue another ROUTE REQUEST to find a new route.
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Related work - AODV
• AODV (Ad-hoc On-demand Distance Vector)• Source node broadcasts RREQ until the packets reach to
destination node or the intermediate nodes contain the route to the destination node.
• Once receiving RREQ packet, it replies back to the source by the route.
• Every node periodically broadcasts HELLO message to check a broken link.
• When a broken link is detected, RRER will be issued to the source node, then it issues new route discovery
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Related work - CLA
• CLA (Connectionless approach) Routing -Adapt the topology effectively -Do not need to maintain nodes routing table -The nodes are included in the Virtual Cell can relay data packets
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Proposed TLA routing
• TLA (Traffic Light based Approach) routing-When the vehicles stop at the red traffic lights, it is the best chance to forward the data between the vehicles.-Divide the network area into numbers of small “virtual area”.-Select a list of “Virtual Area” to be a route forwarding area between source and destination nodes.
Requirement:• GPS (Global Positioning System)• Digital Map• Sensor
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Proposed TLA Routing
Virtual Area ID set up:• Virtual Area ID Builds on intersection.
Reasons:1. The intersection must have traffic lights.2. The red lights turn on means the
vehicles must stop at the intersection3. It is the best chance to relay the packet messages 4. Reliable and stable, increases the packet delivery ratio
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Proposed TLA Routing
• Virtual Area ID set up S
D
A101A201
A301
A102
A103
A104
A105
A202
A203
A204
A302
A303
A304
A205A2b05
A305
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Proposed TLA Routing
Route Discovery:• Source node floods the RREQ message.• RREQ packet contains Source ID, Destination ID,
Sequence number, and Area record. • Area record contains the order of area IDs.• When Intermediate nodes receive duplicated RREQ, it
attaches the current area ID into area record and forward it.
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Proposed TLA Routing
Route Discovery:• Hop count is not larger than that of the first received
RREQ.• The destination node receives the RREQ:
1. records current area ID 2. records current node’s direction3. sends RREP back via the chosen routes
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Proposed TLA Routing
Data transmission:• Source node sends data according to the Area Record.• Area record includes the whole area IDs which present a route.
Data packet header includes:Source IDDestination IDRoute recordCurrent area ID
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Proposed TLA Routing
Data transmission:• An algorithm for a node C receives a data packet from
node B:1. If C node is a destination node, stop transmitting data
packet.2. If C node is not in the area IDs of the route record, stop
transmitting data packet.3. Otherwise, C node is in the range of area IDs, then delay
T (for listening other nodes’ transmission), if no nodes are transmitting, then C node transmit the data packet.
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Proposed TLA Routing
Delay time of packet transmission
• Where α is a maximum delay constant in m seconds• SPDn is the speed of node n• Distn is the distance between node n and the node m’s virtual
area center.• R is the random number between minimum R to maximum
R.
RDistSPDDELAYn
nn
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Proposed TLA Routing
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Evaluation Parameters
• Simulation Setting for GlomoSim [10]
Simulation Time 900sMobility Model VanetMobiSimTerrain Dimensions 1000*1000MAC Protocol 802.11Data Traffic Generation CBRPacket Size 512 ByteRadio Range 278m
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Evaluation Parameters
• VanetMobiSim[9] Parameters for Road Layouts
22
Simulation Time 900sMax Traffic lights 30Terrain Size 1000m*1000mMin. Speed 1 m/s (3.6km/hr)Max. Speed 15 m/s (54km/hr)Nodes (vehicles) 30, 50, 100, 200Max. acceleration 0.6 m/s2
Normal deceleration 0.5 m/s2
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Effect of Different Number of Nodes
30 50 100 2000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Effect of Different Number of Nodes
TLA(Proposed)CAM
Number of Nodes
Pack
et D
eliv
ery
Ratio
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Effect of Different Number of Nodes
30 50 100 2000
20
40
60
80
100
120
Effect of Different Number of Nodes
TLA(Proposed)CAM
Number of Nodes
End-
to-E
nd D
elay
(ms)
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Conclusion
• We propose a Traffic Light based routing protocol for urban VANETs.
• The proposed TLA improves the delivery ratio by 15% and the end-to-end delay by around 20ms
• Delivering packets to a node which are waiting for the red traffic light effectively improve the throughput (packet delivery ratio)
• Decrease the end-to-end delay by transmitting with stationary nodes
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References
[1] X. Fei, et al., "Performance Study of Live Video Streaming Over Highway Vehicular Ad Hoc Networks," in Vehicular Technology Conference, 2007. VTC-2007 Fall. 2007 IEEE 66th, 2007, pp. 2121-2125.[2] M. K. Marina and S. R. Das, "On-demand multipath distance vector routing in ad hoc networks," in Network Protocols, 2001. Ninth International Conference on, 2001, pp. 14-23.[3] Lee, S.-J.; Gerla, M.;“Split Multipath Routing with Maximally Disjoint Paths in Ad hoc Networks” in IEEE International Conference on Volume: 10, Digital, 2001, pp.3201 – 3205[4] V. K. Goyal, "Multiple Description Coding: Compression Meets the Network," IEEE Signal Processing Magazine, vol. 18, no. 5, pp. 74–94, Sept. 2001.[5] T.Wiegand, G.J. Sullivan, G. Bjøntegaard, A.Luthra: Overview of the H.264/AVC Video Coding Standard. IEEE Transactions on Circuits and Systems for Video Technology, Vol. 13, No. 7, July 2003
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References[6]A.H. Ho, Y.H. Ho, K.A. Hua. Connectionless approach to mobile ad hoc network in street environments, in: Proceedings of IEEE Intelligent Vehicles Symposium (IV 2005). Nevada, USA, 2005.[7]H. Fubler, J. Widmer, M. Kasemann, M. Mauve, H. Hartenstein,
Contention-based forwarding for mobile ad-hoc networks, Elsevier’s Ad-Hoc Networks 1 (4) (2003) 351–369.
[8] Y. Jiazi, et al., "Simulation and Performance Analysis of MP-OLSR for Mobile Ad Hoc Networks," in Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE, 2008, pp. 2235- 2240.[9] M. Fiore, J. Härri, F. Filali, and C. Bonnet, “Vehicular mobility simulation for VANETs,” in 40th Annual Simulation Symposium, March 2007, pp. 301-307.[10] X. Zeng, R. Bagrodia, and M. Gerla, “GloMoSim: A library for parallel simulation of large-scale wireless networks,” in 12th Workshop on Parallel and Distributed Simulations, May 1998, pp. 154-161.
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