1 / 26

Localization With Mobile Anchor Points in Wireless Sensor Networks

Localization With Mobile Anchor Points in Wireless Sensor Networks. Kuo-Feng Ssu, Chia-Ho Ou, and Hewijin Christine Jiaju IEEE TRANSACTION ON VEHICULAR TECHNOLOGY MAY 2005. Outline. Introduction Mobile anchor points localization algorithm System environments and assumption

imogene-villarreal
Download Presentation

Localization With Mobile Anchor Points in Wireless Sensor Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Localization With Mobile Anchor Points in Wireless Sensor Networks Kuo-Feng Ssu, Chia-Ho Ou, and Hewijin Christine Jiaju IEEE TRANSACTION ON VEHICULAR TECHNOLOGY MAY 2005

  2. Outline • Introduction • Mobile anchor points localization algorithm • System environments and assumption • Localization scheme • Enhancements • Performance evaluations

  3. Introduction • The location information is useful for many application, like routing, target tracking… • localization schemes classified into • Range-based • Need node-to-node distances or angles for estimating locations • Have higher location accuracy but require additional hardware • Range-free

  4. Introduction (cont.) • localization schemes classified into • Range-based • Range-free • Do not need the distanceorangle information for localization • Cannot accomplish as high precision as the range-based, but provide an economic approach • This paper develops a range-free localization mechanism with mobile anchor • It can work with obstacle but sensor needed to determine signal strength

  5. System Environments and Assumptions • System environment • Two main assumptions: • Each mobile anchor point has a GPS receiver • Mobile anchor points are able to move

  6. Localization Scheme • The perpendicular bisector of any chord passes through the center of the circle LAB A B C LBC Endpoints of chord AB Center of Circle C C

  7. Beacon Point Selection • Each sensor node maintains beacon points list and visitor list T10 T9 When the life time is expired ( 3*beacon time interval), 1.add last point to beacon points list 2.Remove the id in visitor list When receive beacon sensor check its visitor list If has no id, add T1 to beacon point list If has id, extended the lifetime of the anchor T7 T5 T11 T8 T3 T12 T6 T1 T13 T4 T0 T2 T14 Sensor mobile Anchor T15 • Visitor list • (idk, lifetimek) T16 T17 T18 • Beacon information • Anchor ID • Location • timestamp Beacon points list (idk, locationk, timestampk) Mobile anchor’s communication range T19

  8. Location calculation • The intersection point of Lij and Ljk is the estimated location of the sensor L1 T7 L2 T1 T14 T17

  9. Enhancements- Beacon Scheduling • Mobile anchors broadcasting in this environment may cause collision • result incorrect beacon point • So the scheduling for broadcasting beacon messages is jittered Beacon interval = beacon interval + jitter time Randomly selected from [ 0, ( 0.01*beacon interval )]

  10. Enhancements- Obstacle Tolerance Node S would recorded the wrong beacon point

  11. Enhancements- Obstacle Tolerance2 • Usesignal strength The beacon point have different signal strength so don’t use it

  12. Enhancements- Chord Selection • Incorrect beacon points due to • Collision • Inappropriate beacon interval Sensor Beacon point Incorrect beacon point

  13. Enhancements- Chord Selection 2 • If the length of incorrect chord shorter, it make a bigger location error • A threshold (λ) for the length of a chord is used

  14. Analysis- Localization Accuracy Sensor Beacon point

  15. Analysis- Localization Accuracy Incorrect beacon point Incorrect sensor location

  16. Analysis- Localization Accuracy Shorter chord Long chord

  17. Performance Evaluation • Normal Environment • Sensor field = 100 * 100m2 • 319 sensor nodes were randomly deployed • When all sensor nodes obtained their locations, the simulation was terminated • Two schemes were evaluated for performance comparisons • Centroid and Constraint

  18. Centroid and Constraint • Centroid Anchor A Anchor B Sensor S Anchor C

  19. Sensor S Anchor A Centroid and Constraint (cont.) • Constraint Sensor S Anchor A

  20. Location Error (m) periodical random Beacon interval Simulation Results- Beacon Scheduling • Compares randomized and periodical broadcasting schemes Beacon interval = beacon interval + jitter time

  21. Simulation Results- Chord Selection • Location error fell down rapidly with the chord selection increase increase

  22. Simulation Results- Radio Range • Larger range , reduce more execution time Each sensor had to obtain 200 beacon message for localization Only three appropriate beacon points were needed

  23. Simulation Results- Moving Speed • Faster moving speed, reduced more execution time steady reduce

  24. Simulation Results- Number of Anchor • Our scheme achieved the best performance Increasing the number of anchor helped to reduce the execution time and beacon overhead

  25. Simulation Results- Obstacle Tolerance

  26. Conclusion • Several enhancements can improve performance • Chord selection • Randomized beacon scheduling • Advanced beacon point selection • Our mechanism outperformed two previous range-free localization schemes

More Related