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

NCU ACN Lab.2ICS 2006 Outline Introduction Related Work The SEEKER Location Service Simulation Result Conclusion

NCU ACN Lab.3ICS 2006 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.4ICS 2006 Greedy Forwarding S a D b c e

NCU ACN Lab.5ICS 2006 Location Service Position-Based routing requires a location service to support : –location registration –location update –location query

NCU ACN Lab.6ICS 2006 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.7ICS 2006 Outline Introduction Related work The SEEKER Location Service Simulation Result Conclusion

NCU ACN Lab.8ICS 2006 The Classification of Rendezvous-Based Location Services

NCU ACN Lab.9ICS 2006 Quorum-Based (XYLS) [Stojmenovic 1999] Updates Queries Intersection

NCU ACN Lab.10ICS 2006 Hierarchical-Based (GLS) [Li et 2000] 26, 31, 32, 74, 75, 79,

NCU ACN Lab.11ICS 2006 Hash-Based (SLURP) [S.-C. M 2001] A A RegionHome Region B

NCU ACN Lab.12ICS 2006 Outline Introduction Related Work The SEEKER Location Service Simulation Result Conclusion

NCU ACN Lab.13ICS 2006 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.14ICS 2006 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.15ICS 2006 SEEKER – Location Update Initial 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 Virtual destination Terminal node

NCU ACN Lab.16ICS 2006 SEEKER – Location Query A B C Unicast Query- Reply Unicast Query- Request Broadcast Query Request Broadcast Query Reply

NCU ACN Lab.17ICS 2006 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: 1.Calculate the average speed and transform it into the new update interval by the terminal node 2.Spread the new update interval to the terminal node’s neighbors 3.Spread the new update interval by LOC packets

NCU ACN Lab.18ICS 2006 Transform Average Speed into Update Interval 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 Update interval Range of Speed levels (s) 50 (s) 30 (s) 25 (s) 20 (s) (s) m/s

NCU ACN Lab.19ICS 2006 Procedure of Adaptive Location Update A LOC Next update Hello packet

NCU ACN Lab.20ICS 2006 Outline Introduction Related Work The SEEKER Location Service Simulation Result Conclusion

NCU ACN Lab.21ICS 2006 Simulation Result Simulation environment –Simulate by ns2 –Node density within 100 nodes/km 2 –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.22ICS 2006 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.23ICS 2006 Update Overhead

NCU ACN Lab.24ICS 2006 Query Overhead (reply excluded)

NCU ACN Lab.25ICS 2006 Query Success Rate (QSR)

NCU ACN Lab.26ICS 2006 Packet Delivery Rate (PDR)

NCU ACN Lab.27ICS 2006 Outline Introduction Related Work The SEEKER Location Service Simulation Result Conclusion

NCU ACN Lab.28ICS 2006 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.29ICS 2006 Thank you! Questions and Comments?