Measures of Dispersion and Variability: Range, QD, AD and SD
2006-06-24GVGrid-English-IWQoS2006
1. June,20,2006 IWQoS2006@Yale University 1 GVGrid: A QoS Routing Protocol for Vehicular Ad Hoc Networks Weihua Sun, Hirozumi Yamaguchi, Koji Yukimasa, Shinji Kusumoto Osaka University, Japan
2. June,20,2006 IWQoS2006@Yale University 2 Background Vehicular Ad Hoc NETworks (VANETs) Special type of MANETs which use vehicles as nodes VANETs are used for Local information propagation for safety driving & driving assistance (traffic jam, accident, parking, shops/restaurants information etc.) Extend wireless range of ISP base stations IN OUT Internet
3. June,20,2006 IWQoS2006@Yale University 3 Research Goal & Related Work Research goal to design a routing protocol to build a stable inter-vehicle route Existing work None of them uses vehicles’ movement characteristics
4. June,20,2006 IWQoS2006@Yale University 4 Our Proposal We propose a routing protocol called GVGrid on VANETs We consider that the following vehicles’ movement characteristics are important for stable routes Density A certain density brings lower relative speed Alternate nodes can be easily found when a route is broken Direction & Speed The same direction and similar speeds are better for link stability There are many vehicles on major streets – density is high, and directions & speeds are similar GVGrid establishes a route along major streets to achieve longer route lifetime
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6. June,20,2006 IWQoS2006@Yale University 6 Assumptions Each node is equipped with Same Ranged Wireless Device IEEE802.11, etc. Car Navigator (GPS + Digital Map) Accurate geographic information, and roads and direction information Grid Geographic region is divided into grids Grid size w is determined based on r so that node in every grid can communicate with nodes in neighboring grids Nodes exchange the following information by hello messages Position, Road, Direction and ID
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9. June,20,2006 IWQoS2006@Yale University 10 Route Lifetime Estimation Leader d’ calculates the Number of Disconnections per Time (NDT) of the candidate routes using the information in RREQs (1) (2) (3.1) (3.2) (3.3) d’ S S does not move d’ will leave from D Turn Turn & Signal Stop Signal stop
10. June,20,2006 IWQoS2006@Yale University 11 Route Maintenance Process We restore the original route when the route is broken because the original route is considered the best route based on the estimated route lifetime For this purpose, the grids of original driving route are memorized by all nodes on the route When the route is broken Exclude all nodes outside the original route Repair the route by nodes which remain on the route Select alternate nodes from the front grid if no node remains in the grid
11. June,20,2006 IWQoS2006@Yale University 12 Simulation setup X X Traffic simulator NETSTREAM (Toyota Central R&D Labs) Wave range: 200m Grid size: 70m Field size: 1,500m x 1,500m Route lengths: 500m 1,000m 1,500m 2,000m Node max speeds: 8.3m/s~16.6m/s Density: 720/km2 (3~6/grid), 240/km2 (1~2/grid) Message collision was not considered Propagation Model Basically only Line-of-Sight is considered Exceptionally, nodes nearby intersection within 30 meters can communicate with nodes in the same region
12. June,20,2006 IWQoS2006@Yale University 13 Implementation of GPCR (for Comparison Purpose) d2 d2 d1 d1 d1 d2 X <1> <2> <3> <4> <5> <6> An on-demand geographic routing protocol for VANETs[3] GPCR searches the network in the depth-first. greedy forwarding way When the route is broken, all links were disabled without repairing GPCR does not exploit vehicles’ moving characteristics to improve the route lifetime and stability of communication [3]C. Lochert, M. Mauve, H. Fusler, and H. Hartenstein. Geographic routing in city scenarios. ACM SIGMOBILE Mobile Computing and Communications Review, pages 69-72, 2005. o d w z x p q v y u s
13. June,20,2006 IWQoS2006@Yale University 14 Performance Metrics Route Lifetime The whole route’s lifetime shows the stability The longer route lifetime is better to provide a stable data transmission Link Lifetime The lifetime of node-to-node links shows the similarity of nodes’ movement Higher link lifetime can help the route’s stability Packet Delay and Route Connection Status Low packet delay and stable connection is important forhigh quality data transmission service
14. June,20,2006 IWQoS2006@Yale University 15 Ave. Route Lifetime (Dense) 10 The number of hops is more than 30. This is too far to maintain a stable network 8 GVGrid 6 Route Lifetime (s) 4 2 GPCR GVGrid shows good performance in short route length 1000 1500 2000 500 S- D Route Length (m)
15. June,20,2006 IWQoS2006@Yale University 16 Link Lifetime Distribution Link lifetime is very long in GVGrid because these links can be reused in maintenance process 30 25 Because GPCR does not repair the route, all links are disabled when the route is broken GVGrid 20 15 Link Lifetime (s) 10 GPCR 5 0 500 1000 1500 2000 S-D Route Length (m)
16. June,20,2006 IWQoS2006@Yale University 17 Packet Delay (distance=500m) 1000 GVGrid GPCR 800 Broken Broken 600 Delay (ms) Delay (ms) GVGrid broke 15 times GPCR broke 19 times 400 200 0 200 400 600 800 1000 0 200 400 600 800 1000 Timeline (s) Timeline (s) The delay of GVGrid is a little more than GPCR, because the number of hops of GVGrid is larger than GPCR Stable connection is important for high quality data transmission.
17. June,20,2006 IWQoS2006@Yale University 18 Conclusion We have proposed a QoS routing protocol GVGrid for VANETs GVGrid constructs a route along major streets, taking nodes toward the same direction as possible Through simulation results, we confirmed that GVGrid could provide high stability for high quality data transmission services Future work More accurate simulations in various maps, densities and mobility Make a network simulator inter-work with the traffic simulator to simulate the message collisions and so on
19. June,20,2006 IWQoS2006@Yale University 20 C : Signal cycle ρ: Ratio of the green light time in C θ: Probability that a node stays on the road after passes an intersection
