Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.



Published on


Published in: Technology, Business
  • Be the first to comment

  • Be the first to like this


  1. 1. Performance Comparison of Three Location Service Algorithms for Vehicular Ad Hoc Networks Wan Chih Chang
  2. 2. Outline <ul><li>Intersection Location Service (ILS) </li></ul><ul><li>Grid Location Service (GLS) </li></ul><ul><li>Hierarchy Location Service (HLS) </li></ul>
  3. 3. DREAM Homezone <ul><li>The Distance Routing Effect Algorithm for Mobility </li></ul><ul><li>Uses flooding to spread position information </li></ul><ul><li>The capacity of the network is substantially decreased as a result of message flooding, especially in situations where the nodes make frequent position changes </li></ul><ul><li>Homezone does not require flooding </li></ul><ul><li>The homezone becomes empty, and some cars may get into situations where their default location servers are temporarily unavailable. </li></ul>
  4. 4. Grid Location Service (GLS) <ul><li>Divides the area of the entire ad hoc network into a hierarchy of squares forming a quad-tree. </li></ul><ul><li>Each node selects one node in each element of every levels of the quad-tree as a location server. </li></ul><ul><li>The density of location servers for a particular node is high in areas close to the node and become exponentially sparse as the distance to the node increases. </li></ul>
  5. 5. Hierarchy Location Service (HLS) <ul><li>Partitions the area of the ad hoc network into cells. </li></ul><ul><li>The cells are grouped into regions level by level. </li></ul><ul><li>A node uses a hierarchy of location servers to store its location information. </li></ul><ul><li>The problem of empty cells where location updates or requests may run into is solved by temporary servers through a handover mechanism to bridge the gap. </li></ul>
  6. 6. Intersection Location Service (ILS) <ul><li>Consistent Hashing </li></ul><ul><li>Query for Location </li></ul><ul><li>Dynamic Operation and Failure Recovery </li></ul><ul><li>Location Update </li></ul>
  7. 7. Consistent Hashing
  8. 8. Query for Location
  9. 10. Dynamic Operation and Failure Recovery <ul><li>Leaving the network </li></ul><ul><li>Joining the network </li></ul>
  10. 11. Location Update
  11. 12. First Simulation <ul><li>Table 1 : Parameters for the study of car speeds. </li></ul><ul><ul><li>Number of cars 80 </li></ul></ul><ul><ul><li>Area size (m2) 900x900 </li></ul></ul><ul><ul><li>Mean velocity (m/s) 10, 20, 30,40 </li></ul></ul><ul><ul><li>Velocity deviation (m/s) 5 </li></ul></ul><ul><ul><li>Pause time (s) 5 </li></ul></ul>
  12. 13. Query success ratio (QSR)
  13. 14. Second Simulation <ul><li>Table 2 : Parameters for the study of car speeds </li></ul><ul><ul><li>Number of nodes (cars) 20~80 </li></ul></ul><ul><ul><li>Area size (m2) 900x900 </li></ul></ul><ul><ul><li>Mean velocity (m/s) 40 </li></ul></ul><ul><ul><li>Velocity deviation (m/s) 5 </li></ul></ul><ul><ul><li>Pause time (s) 5 </li></ul></ul>
  14. 16. Third Simulation <ul><ul><li>The pause time at intersections to be uniformly distributed in the interval [0,5] s instead of a constant of 5 s. </li></ul></ul><ul><ul><li>The initial position of each car is set in a way such that its distance to the nearest intersection is uniformly distributed from [0,100] m instead of a constant of 0 m. </li></ul></ul><ul><li>All the simulation parameters are the same as those in Table 2 </li></ul>
  15. 18. Number of cars 80 Mean velocity (m/s) 10, 20, 30,40
  16. 19. Large Scale Simulations <ul><li>Table 3 : Parameters for the large scale simulations. </li></ul><ul><ul><li>Number of nodes 80, 180, 320 </li></ul></ul><ul><ul><li>Area size (m2) 900x900, 1350x1350, 1800x1800 </li></ul></ul><ul><ul><li>Mean velocity (m/s) 40 </li></ul></ul><ul><ul><li>Velocity deviation (m/s) 5 </li></ul></ul><ul><ul><li>Pause time (s) [0,5] </li></ul></ul><ul><ul><li>The number of intersections increases from 25 to 64 and 100 as the size of areas increases. </li></ul></ul><ul><ul><li>Both the size of cells in HLS and the size of order-one squares in GLS increase from 112.5x112.5 m 2 to 168.75x168.75 m 2 and 225x225 m 2 . </li></ul></ul>
  17. 20. The area size varying from 900x900 m 2 to 1350x1350 m 2 and 1800x1800 m 2
  18. 21. The area size of 1800*1800 m 2
  19. 22. Conclusion <ul><li>ILS, a location service algorithm that is designed to work in the city environments with streets and intersections. </li></ul><ul><li>increased success ratios under different network topologies. </li></ul><ul><li>ILS algorithm not only remains robust at high car speeds but also demonstrates higher scalability than the other two with respect to network size. </li></ul>
  20. 23. ~Thank you~