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SEEKER: An Adaptive and Scalable Location Service for Mobile Ad Hoc Networks

This paper presents the SEEKER location service, which aims to achieve high scalability, query accuracy, and success rate, as well as low protocol and maintenance overhead. It introduces the concept of adaptive location updates and discusses simulation results comparing SEEKER with other location services.

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SEEKER: An Adaptive and Scalable Location Service for Mobile Ad Hoc Networks

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  1. SEEKER: An Adaptive and Scalable Location Service for Mobile Ad Hoc NetworksJehn-Ruey Jiang and Wei-Jiun Ling Presented by Jehn-Ruey Jiang National Central University

  2. Outline • Introduction • Related Work • The SEEKER Location Service • Simulation Result • Conclusion NCU ACN Lab.

  3. Categories of Routing Protocols for MANETs • Topology-Based routing protocols: • AODV, DSR …etc • Position-Based routing protocols: • Each node knows its location via a GPS or the like • A source node knows the destination location • Routing via greedy forwarding or the like More Scalable NCU ACN Lab.

  4. Greedy Forwarding e D b c S a NCU ACN Lab.

  5. Location Service • Position-Based routing requires a location service to support : • location registration • location update • location query NCU ACN Lab.

  6. Problem • A good location service must have : • High scalability • High query accuracy and success rate • Low protocol overhead • Update and maintenance overhead • Query overhead • How to design a good location service? NCU ACN Lab.

  7. Outline • Introduction • Related work • The SEEKER Location Service • Simulation Result • Conclusion NCU ACN Lab.

  8. The Classification of Rendezvous-Based LocationServices NCU ACN Lab.

  9. Updates Queries Intersection Quorum-Based (XYLS) [Stojmenovic 1999] NCU ACN Lab.

  10. 27 23 63 99 75 91 17 33 2 87 62 12 32 74 55 79 98 8 56 4 43 26 23 12 23 81 31 28 23 23 23 23 Hierarchical-Based (GLS) [Li et al. @MobiCom 2000] 26, 31, 32, 74, 75, 79, 98 NCU ACN Lab.

  11. Region Home Region A A B Hash-Based (SLURP) [S.-C. M 2001] NCU ACN Lab.

  12. Outline • Introduction • Related Work • The SEEKER Location Service • Simulation Result • Conclusion NCU ACN Lab.

  13. SEEKER - Overview • Control overhead can be reduced by aggregate update • Adapt to mobility by adjusting the frequency of location updates to further reduce overhead: adaptive update • Goals: to achieve • High scalability • High query accuracy and success rate • Low protocol overhead NCU ACN Lab.

  14. SEEKER – Aggregate Update • Initial nodes send LOC packet (location update packet) periodically. • The initial node sets a virtual destination to deliver the LOC packet to. • The LOC packet is relayed by greedy forwarding until it reaches the terminal node. • The nodes in the path from the initial node to the terminal node serve as the location servers for all the nodes in the same row of regions. NCU ACN Lab.

  15. SEEKER – Location Update Terminal node Initial node : Self-selection by testing neighbors in the east and west Ex. If no node is to the west of a node, it will be the initial node to send LOC to the east Initial node Virtual destination NCU ACN Lab.

  16. SEEKER – Location Query Unicast Query-Request C Broadcast Query Request B Unicast Query-Reply A Broadcast Query Reply NCU ACN Lab.

  17. SEEKER - Adaptive Location Update • Observation: there is a tradeoff between update interval and query accuracy • Basic idea: let the terminal node calculate the average speed of nodes of each row • Procedures: • Calculate the average speed and transform it into the new update interval by the terminal node • Spread the new update interval to the terminal node’s neighbors • Spread the new update interval by LOC packets NCU ACN Lab.

  18. Define speed levels, ex: 2.5 m/s, 5.0 m/s, 7.5 m/s, 10.0 m/s, and 12.5 m/s Adopt ½ difference (1.25 m/s) to be interval boundaries Next update interval = Transmission range / Speed level m/s 1.25 2.5 5.0 10.0 12.5 0 7.5 200 (s) 100 (s) 50 (s) 30 (s) 25 (s) 20 (s) Update interval Range of Speed levels Transform Average Speed into Update Interval NCU ACN Lab.

  19. Procedure of Adaptive Location Update Hello packet A LOC Next update NCU ACN Lab.

  20. Outline • Introduction • Related Work • The SEEKER Location Service • Simulation Result • Conclusion NCU ACN Lab.

  21. Simulation Result • Simulation environment • Simulate by ns2 • Node density within 100 nodes/km2 • Random waypoint with speed 0~10 m/s • 300 seconds per simulation • Metrics • Control overhead (update + query) • QSR (Query Success Rate) • PDR (Packet Delivery Rate) NCU ACN Lab.

  22. Comparison • Up to 600 nodes • Compared with GLS and HIGH-GRADE • Bandwidth is 2Mbps • The performance of fixed update interval vs. adaptive update interval NCU ACN Lab.

  23. Update Overhead NCU ACN Lab.

  24. Query Overhead (reply excluded) NCU ACN Lab.

  25. Query Success Rate (QSR) NCU ACN Lab.

  26. Packet Delivery Rate (PDR) NCU ACN Lab.

  27. Outline • Introduction • Related Work • The SEEKER Location Service • Simulation Result • Conclusion NCU ACN Lab.

  28. Conclusion • SEEKER achieves comparably low control overhead by using aggregate update • Control overhead (esp. update overhead) can be further reduced by adaptive update • SEEKER achieves • comparably high scalability (2000 nodes) • comparably high query success rate • comparably high query accuracy • comparably low maintenance cost NCU ACN Lab.

  29. Thank you! Questions and Comments? NCU ACN Lab.

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