1. KAIS T Sensor Deployment Based on Virtual Forces Reference: Yi Zou and Krishnendu Chakarabarty, “Sensor Deployment and Target Localization Based on Virtual Forces”, Department of Electrical and Computer Engineering, Duke University, IEEE INFOCOM 2003 2007. 10. 4 Hong Jae-Young

2. 2/18 Sensor Deployment Based on VFA Contents Introduction Related Prior Work Virtual Force Algorithm Simulation Results Conclusion

3. 3/18 Sensor Deployment Based on VFA Introduction The effectiveness of distributed sensor networks (DSN) Depends on the sensor deployment Coverage, communication cost, resource management Random deployment Practical for military applications Not always lead to effective coverage New sensor placement strategy Maximize the coverage for a given number of sensors Virtual Force Algorithm (VFA) as a sensor deployment of sensors Enhance the coverage after initial random placement of sensors

4. 4/18 Sensor Deployment Based on VFA Related Prior Work A variety of work for Sensor deployment problems A bidding Protocol for Deploying Mobile Sensor Sensor Deployment and Sensor Planning for Elusive Targets A priori knowledge about possible target No information about potential target Mobile Sensor Network Deployment Using Potential Field Each robot is a sensor node Expensive and a large amount of computation Coverage problems in wireless ad-hoc sensor networks Self-localization Sensor nodes are should be highly mobile and move frequently Radar and sonar coverage

5. 5/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (1/7) Basic assumptions After the initial random deployment, all sensor nodes are able to communicate with the cluster head The cluster head is responsible for executing the VFA and managing the one-time movement of sensors to the desired locations Basic idea of VFA Each sensor behaves as a “Source of force” for all other sensors Positive (Attractive) vs. Negative (Repulsive) Globally uniform sensor placement

6. 6/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (2/7) Sensor Detection Models Consider an n by m sensor field grid K sensor deployed in the random deployment stage Each sensor has a detection range r Let s i deployed at point (x i, y i ), any point P at (x, y) Binary Sensor Detection Model Probabilistic Sensor Detection Model r n m r r P (x, y)

7. 7/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (3/7) Virtual Forces Notation Let the total force action on sensor s i be denoted by Let the force exerted on s i by another sensor s j be denoted by Let total repulsive force on s i by Let total attractive force on s i by Virtual force calculation in the VFA Total force on s i,

8. 8/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (4/7) An example of virtual forces with four sensors If we assume that d 12 >d th, d 13 <d th, d 14 =d th, s 2 exerts an attractive force on s 1, s 3 exerts a repulsive force on s 1, s 4 exerts no force on s 1 If r e =0 then Binary sensor detection model Make d ij as close to 2r as possible

9. 9/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (5/7) Non-overlapped and overlapped sensor coverage areas Non-overlapped areaOverlapped area Non-overlapped area Minimize “wasted overlap” A few grid points are not covered by any sensor Overlapped area More sensors for grid coverage Therefore, adopt the Non-overlapped area Total Coverage area is

10. 10/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (6/7) If r e >0, r e is not negligible Probabilistic Sensor Detection Model Grid points are not covered with the same probability Necessary overlap sensor detection areas

11. 11/18 Sensor Deployment Based on VFA Virtual Force Algorithm : VFA (7/7) Coverage Evaluation Virtual Forces among sensors Move sensor virtually

12. 12/18 Sensor Deployment Based on VFA Simulation Results (1/5) Parameters A total of 20 sensors Random placement Detection radius as 5 unit (r=5) Large detection error as 3 unit (r e =3) 50 by 50 sensor field Pentium III 1.0GHz PC using MATLAB

13. 13/18 Sensor Deployment Based on VFA Simulation Results (2/5) Binary Sensor Detection Model

14. 14/18 Sensor Deployment Based on VFA Simulation Results (3/5) Binary Sensor Detection Model

15. 15/18 Sensor Deployment Based on VFA Simulation Results (4/5) Probabilistic sensor detection model

16. 16/18 Sensor Deployment Based on VFA Simulation Results (5/5)

17. 17/18 Sensor Deployment Based on VFA Conclusion Virtual Force Algorithm Practical approach for sensor deployment Advantages Negligible computation time Small amount of computation One time repositioning of the sensors Low-cost

18. 18/18 Sensor Deployment Based on VFA Questions & Comments Any Questions? Comments?