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  1. 1. June,20,2006<br />IWQoS2006@Yale University<br />1<br />GVGrid: A QoS Routing Protocol for Vehicular Ad Hoc Networks<br />Weihua Sun, Hirozumi Yamaguchi,<br />Koji Yukimasa, Shinji Kusumoto<br />Osaka University, Japan<br />
  2. 2. June,20,2006<br />IWQoS2006@Yale University<br />2<br />Background<br />Vehicular Ad Hoc NETworks (VANETs)<br />Special type of MANETs which use vehicles as nodes<br />VANETs are used for<br />Local information propagation for safety driving & driving assistance (traffic jam, accident, parking, shops/restaurants information etc.)<br />Extend wireless range of ISP base stations<br />IN<br />OUT<br />Internet<br />
  3. 3. June,20,2006<br />IWQoS2006@Yale University<br />3<br />Research Goal & Related Work<br />Research goal<br />to design a routing protocol to build a stable inter-vehicle route<br />Existing work<br />None of them uses vehicles’ movement characteristics<br />
  4. 4. June,20,2006<br />IWQoS2006@Yale University<br />4<br />Our Proposal<br />We propose a routing protocol called GVGrid on VANETs<br />We consider that the following vehicles’ movement characteristics are important for stable routes<br />Density<br />A certain density brings lower relative speed<br />Alternate nodes can be easily found when a route is broken<br />Direction & Speed<br />The same direction and similar speeds are better for link stability<br />There are many vehicles on major streets – density is high, and directions & speeds are similar <br />GVGrid establishes a route along major streets to achieve longer route lifetime<br />
  5. 5. June,20,2006<br />IWQoS2006@Yale University<br />5<br />Protocol GVGrid Overview<br />D<br />S<br />D<br />a<br />c<br />b<br />S<br /><ul><li>GVGrid establishes a stable network route between 2 fixed regions</li></ul>GVGrid selects a network route along major streets <br />Nodes toward the same direction are preferred<br />
  6. 6. June,20,2006<br />IWQoS2006@Yale University<br />6<br />Assumptions<br />Each node is equipped with<br />Same Ranged Wireless Device<br />IEEE802.11, etc.<br />Car Navigator (GPS + Digital Map)<br />Accurate geographic information, and roads and direction information<br />Grid<br />Geographic region is divided into grids<br />Grid size w is determined based on r so that node in every grid can communicate with nodes in neighboring grids<br />Nodes exchange the following information by hello messages<br />Position, Road, Direction and ID<br />
  7. 7. June,20,2006<br />IWQoS2006@Yale University<br />7<br />Route Discovery Process (1/2)<br />D<br />S<br />Find all route candidates that follow driving routes from S to D<br />S sets a forwarding zone<br />S sends a RREQ message to a node in every neighboring grid<br />Each node forwards the RREQ message in the same way<br /><ul><li>Road and node information is added when RREQ is forwarded </li></li></ul><li>June,20,2006<br />IWQoS2006@Yale University<br />8<br />Neighbor Selection Strategyin RREQ Forwarding<br />Only one node is selected in a neighboring grid<br />A node on the same street is selected prior to the others<br />If there are multiple nodes, a node with the same direction is selected<br />If there is no such a node, a node on the crossing street is selected<br />w<br /><22><br /><02><br /><12><br />x<br />u<br />z<br />q<br /><11><br />v<br /><01><br /><21><br />X<br />y<br /><00><br /><10><br /><20><br />
  8. 8. June,20,2006<br />IWQoS2006@Yale University<br />9<br />Route Discovery Process (2/2)<br />D<br />S<br />Confirm the best route from plural candidates<br />Node d’ with the smallest ID in grid D becomes the “leader” node<br />Node d’ calculates the best route from the information included in RREQs<br /><ul><li>By estimating route lifetime</li></ul>Node d’ transfers RREP to S via the selected route to confirm it<br />d’<br />
  9. 9. June,20,2006<br />IWQoS2006@Yale University<br />10<br />Route Lifetime Estimation<br />Leader d’ calculates the Number of Disconnections per Time (NDT) of the candidate routes using the information in RREQs<br />(1)<br />(2)<br />(3.1)<br />(3.2)<br />(3.3)<br />d’<br />S<br />S does not<br />move<br />d’ will leave<br />from D<br />Turn<br />Turn &<br />Signal Stop<br />Signal stop<br />
  10. 10. June,20,2006<br />IWQoS2006@Yale University<br />11<br />Route Maintenance Process<br />We restore the original route when the route is broken<br />because the original route is considered the best route based on the estimated route lifetime<br />For this purpose, the grids of original driving route are memorized by all nodes on the route<br />When the route is broken<br />Exclude all nodes outside the original route<br />Repair the route by nodes which remain on the route<br />Select alternate nodes from the front grid if no node remains in the grid<br />
  11. 11. June,20,2006<br />IWQoS2006@Yale University<br />12<br />Simulation setup<br />X<br />X<br />Traffic simulator NETSTREAM (Toyota Central R&D Labs)<br />Wave range: 200m<br />Grid size: 70m<br />Field size: 1,500m x 1,500m<br />Route lengths: 500m 1,000m 1,500m 2,000m<br />Node max speeds: 8.3m/s~16.6m/s<br />Density: 720/km2 (3~6/grid), 240/km2 (1~2/grid)<br />Message collision was not considered<br />Propagation Model<br />Basically only Line-of-Sight is considered<br />Exceptionally, nodes nearby intersection within 30 meters can communicate with nodes in the same region<br />
  12. 12. June,20,2006<br />IWQoS2006@Yale University<br />13<br />Implementation of GPCR (for Comparison Purpose)<br />d2<br />d2<br />d1<br />d1<br />d1<br />d2<br />X<br /><1><br /><2><br /><3><br /><4><br /><5><br /><6><br />An on-demand geographic routing protocol for VANETs[3]<br />GPCR searches the network in the depth-first. greedy forwarding way<br />When the route is broken, all links were disabled without repairing<br />GPCR does not exploit vehicles’ moving characteristics to improve the route lifetime and stability of communication<br />[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.<br />o<br />d<br />w<br />z<br />x<br />p<br />q<br />v<br />y<br />u<br />s<br />
  13. 13. June,20,2006<br />IWQoS2006@Yale University<br />14<br />Performance Metrics<br />Route Lifetime<br />The whole route’s lifetime shows the stability<br />The longer route lifetime is better to provide a stable data transmission<br />Link Lifetime<br />The lifetime of node-to-node links shows the similarity of nodes’ movement<br />Higher link lifetime can help the route’s stability<br />Packet Delay and Route Connection Status<br />Low packet delay and stable connection is important forhigh quality data transmission service<br />
  14. 14. June,20,2006<br />IWQoS2006@Yale University<br />15<br />Ave. Route Lifetime (Dense)<br />10<br />The number of hops is more than 30. This is too far to maintain a stable network<br />8<br />GVGrid<br />6<br />Route Lifetime (s)<br />4<br />2<br />GPCR<br />GVGrid shows good performance in short route length <br />1000<br />1500<br />2000<br />500<br />S- D Route Length (m)<br />
  15. 15. June,20,2006<br />IWQoS2006@Yale University<br />16<br />Link Lifetime Distribution<br />Link lifetime is very long in GVGrid because these links can be reused in maintenance process <br />30<br />25<br />Because GPCR does not repair the route, all links are disabled when the route is broken<br />GVGrid<br />20<br />15<br />Link Lifetime (s)<br />10<br />GPCR<br />5<br />0<br />500<br />1000<br />1500<br />2000<br />S-D Route Length (m)<br />
  16. 16. June,20,2006<br />IWQoS2006@Yale University<br />17<br />Packet Delay (distance=500m)<br />1000<br />GVGrid<br />GPCR<br />800<br />Broken<br />Broken<br />600<br />Delay (ms)<br />Delay (ms)<br />GVGrid broke 15 times<br />GPCR broke 19 times<br />400<br />200<br />0<br />200<br />400<br />600<br />800<br />1000<br />0<br />200<br />400<br />600<br />800<br />1000<br />Timeline (s)<br />Timeline (s)<br />The delay of GVGrid is a little more than GPCR, because the number of hops of GVGrid is larger than GPCR<br />Stable connection is important for high quality data transmission.<br />
  17. 17. June,20,2006<br />IWQoS2006@Yale University<br />18<br />Conclusion<br />We have proposed a QoS routing protocol GVGrid for VANETs<br />GVGrid constructs a route along major streets, taking nodes toward the same direction as possible<br />Through simulation results, we confirmed that GVGrid could provide high stability for high quality data transmission services<br />Future work<br />More accurate simulations in various maps, densities and mobility<br />Make a network simulator inter-work with the traffic simulator to simulate the message collisions and so on<br />
  18. 18. June,20,2006<br />IWQoS2006@Yale University<br />19<br />Thank You For Your Attention<br />
  19. 19. June,20,2006<br />IWQoS2006@Yale University<br />20<br />C : Signal cycle<br />ρ: Ratio of the green light time in C <br />θ: Probability that a node stays on the road after passes an intersection<br />