A Bidding Protocol for Deploying Mobile Sensors

1. A Bidding Protocol for Deploying Mobile Sensors Guiling Wang, Guohong Cao, Tom LaPorta The Pennsylvania State University IEEE, ICNP 03 발표자 : 권 영 진

2. Contents • Introduction • Voronoi diagram • Bidding protocol(key concepts, remained issues) • Performance evaluations • Conclusion A Bidding Protocol for Deploying Mobile Sensors

3. Introduction ( 1/2 ) • Mobile sensor • Problems : How to deploy mobile sensors efficiently? • “Three distributed self-deployment protocols” (Movement-Assisted Sensor Deployment, IEEE infocom 04) • Use only mobile sensor  Not cost-effective A Bidding Protocol for Deploying Mobile Sensors

4. Introduction ( 2/2 ) • “Bidding protocol” • Key idea : static sensor + mobile sensor Coverage holes : the area that sensor cannot cover • Static sensor : detection of coverage holes • Mobile sensor : heal of coverage holes Sensor circle Coverage holes Hole healing Static sensor Mobile sensor A Bidding Protocol for Deploying Mobile Sensors

5. Terminologies of Voronoi diagram • Voronoi cell • Voronoi diagram A Bidding Protocol for Deploying Mobile Sensors

6. Applying Voronoi diagram to Mobile sensor Put sensor on site points  Each sensor is responsible for the sensing task in Voronoi cells  Each sensor can examine the coverage hole locally sensor A Bidding Protocol for Deploying Mobile Sensors

7. Bidding protocol ( key concepts) ( 1/7 ) • Important questions • How to estimate coverage hole? • Which mobile sensor should move to the place? • Where should the mobile sensor move? • Bid ( for static sensor ) • estimated size of hole • Base price ( for mobile sensor ) • estimate of generated coverage hole after it leaves the current place A Bidding Protocol for Deploying Mobile Sensors

8. Bidding protocol ( key concepts) ( 2/7 ) • Bid Estimation( in Static Sensor ) • Farthest Voronoi vertex is the target location of mobile sensor • Bid is the area of the inner circle Healing of most largest hole Bid = π* ( d – sensing_range)2  relative size of coverage hole d A Bidding Protocol for Deploying Mobile Sensors

9. Bidding protocol ( key concepts) ( 3/7 ) • Base price evaluation( in mobile sensor ) • Initial value is 0 • The accepted bid is a new base price • Meaning of a bid and a base price Base price : estimate of upcoming hole Bid: estimate of healed hole A Bidding Protocol for Deploying Mobile Sensors

10. Bidding protocol ( key concepts) ( 4/7 ) Let’s put it all together ! Bidding protocol flows( round by round ) Construct Voronoi diagram Initialization Service advertisement Bidding Serving Termination A Bidding Protocol for Deploying Mobile Sensors

11. Bidding protocol ( key concepts) ( 5/7 ) • Service advertisement • Mobile sensor broadcasts their base price and location • Base price is set to zero initially • Bidding • Calculate bids and target location for the mobile sensor • Send bids to closest mobile sensor whose base price is lower than bids A Bidding Protocol for Deploying Mobile Sensors

12. Bidding protocol ( key concepts) ( 6/7 ) • Serving • Mobile sensor choose the highest bids and heal coverage holes • Accepted bids becomes new base price • Termination • If base price of all mobile sensor is higher than bids, then terminate A Bidding Protocol for Deploying Mobile Sensors

13. Bidding protocol ( key concepts) ( 7/7 ) Static sensor 40 sensors, 12 mobile sensors Mobile sensor 82% coverage 93% coverage at round 5 A Bidding Protocol for Deploying Mobile Sensors

14. Performance evaluations ( 1/3 ) • Evaluation methodology • Main cost • Number of sensor • Number of round • Environment • Ns-2 simulator • 40 sensors and 10 independent experiments • Some considerations • Trade off between cost and coverage • Cost ratio between the mobile sensor and the static sensor A Bidding Protocol for Deploying Mobile Sensors

15. Performance evaluations ( 2/3 ) Trade off The more mobile sensor are used, The better coverage is obtained But the sensor cost will be increased Random deployment : just use static sensor Bidding protocol : static sensor + mobile sensor VEC algorithm : mobile sensor Random deployment Bidding protocol VEC algorithm A Bidding Protocol for Deploying Mobile Sensors

16. Performance evaluations ( 3/3 ) A Bidding Protocol for Deploying Mobile Sensors

17. Conclusions • Voronoi diagram can be applied to a sensor network using a greedy heuristic method • Mixture of a static sensor and a mobile sensor can achieve a good balance between coverage and cost A Bidding Protocol for Deploying Mobile Sensors

18. Extra ( 1/4 ) • Duplicate healing A Bidding Protocol for Deploying Mobile Sensors

19. Extra ( 2/4 ) • Duplicate healing detection A Broadcast B Check if base price of A > base price of B If yes, run detection algorithm If detected, set base price of A to zero A Bidding Protocol for Deploying Mobile Sensors

20. Extra ( 3/4 ) • Detection Algorithm • Detecting threshold = π* ( dmin – sensing_range)2 dmin : Distance to closest neighbor IF ( detecting threshold < new base price || dmin < sensing_range ) THEN duplication occurs A Bidding Protocol for Deploying Mobile Sensors

21. Extra ( 4/4 ) Why Detecting threshold < New base price? A,Bis mobile sensor Nf ’s base price is calculated without consideration of Ne at Nf Detecting threshold < New base price dmin New base price of B Snapshot in the middle of round A Bidding Protocol for Deploying Mobile Sensors