1. June,20,2006IWQoS2006@Yale University1 GVGrid: A QoS Routing Protocol for Vehicular Ad Hoc Networks Weihua Sun, Hirozumi Yamaguchi, Koji Yukimasa, Shinji Kusumoto Osaka University, Japan

2. June,20,2006IWQoS2006@Yale University2 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 Internet IN OUT

3. June,20,2006IWQoS2006@Yale University3 Research Goal & Related Work  Research goal to design a routing protocol to build a stable inter- vehicle route  Existing work Broadcast UMB[7], RBM[8], MDDV[10] VANETs Data dissemination to every node Routing CarNet[14], GPCR[3] VANETs Point-to-point communication Road structure is considered None of them uses vehicles ’ movement characteristics

4. June,20,2006IWQoS2006@Yale University4 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

5. June,20,2006IWQoS2006@Yale University5 Protocol GVGrid Overview  GVGrid establishes a stable network route between 2 fixed regions 1.GVGrid selects a network route along major streets 2.Nodes toward the same direction are preferred

6. June,20,2006IWQoS2006@Yale University6 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

7. June,20,2006IWQoS2006@Yale University7 Route Discovery Process (1/2)  Find all route candidates that follow driving routes from S to D 1.S sets a forwarding zone 2.S sends a RREQ message to a node in every neighboring grid 3.Each node forwards the RREQ message in the same way Road and node information is added when RREQ is forwarded S D

8. June,20,2006IWQoS2006@Yale University8 Neighbor Selection Strategy in RREQ Forwarding  Only one node is selected in a neighboring grid A node on the same street is selected prior to the others If there are multiple nodes, a node with the same direction is selected If there is no such a node, a node on the crossing street is selected u v w x X y zq

9. June,20,2006IWQoS2006@Yale University9 Route Discovery Process (2/2)  Confirm the best route from plural candidates 1.Node d ’ with the smallest ID in grid D becomes the “ leader ” node 2.Node d ’ calculates the best route from the information included in RREQs By estimating route lifetime 3.Node d ’ transfers RREP to S via the selected route to confirm it S D d’d’

10. June,20,2006IWQoS2006@Yale University10 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) S d’d’ S does not move d ’ will leave from D Signal stop TurnTurn & Signal Stop

11. June,20,2006IWQoS2006@Yale University11 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 1.Exclude all nodes outside the original route 2.Repair the route by nodes which remain on the route 3.Select alternate nodes from the front grid if no node remains in the grid

12. June,20,2006IWQoS2006@Yale University12 Simulation setup  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/km 2 (3~6/grid), 240/km 2 (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 X X

13. June,20,2006IWQoS2006@Yale University13 Implementation of GPCR (for Comparison Purpose)  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. d1 d2 d1 d2 d1 d2 X d s u v w x y z o p q

14. June,20,2006IWQoS2006@Yale University14 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 for high quality data transmission service

15. June,20,2006IWQoS2006@Yale University15 Ave. Route Lifetime (Dense) GVGrid GPCR S- D Route Length (m) Route Lifetime (s) The number of hops is more than 30. This is too far to maintain a stable network 100015002000 10 8 6 4 2 500 GVGrid shows good performance in short route length

16. June,20,2006IWQoS2006@Yale University16 Link Lifetime Distribution GPCR GVGrid S-D Route Length (m) Link Lifetime (s) Because GPCR does not repair the route, all links are disabled when the route is broken Link lifetime is very long in GVGrid because these links can be reused in maintenance process 30 25 20 15 10 5 0 500100015002000

17. June,20,2006IWQoS2006@Yale University17 Packet Delay (distance=500m) GVGridGPCR Delay (ms) Timeline (s) Broken 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. GVGrid broke 15 timesGPCR broke 19 times 1000 800 0 200 400 600 200400600800100002004006008001000

18. June,20,2006IWQoS2006@Yale University18 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,20,2006IWQoS2006@Yale University19 Thank You For Your Attention

20. June,20,2006IWQoS2006@Yale University20  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