1. Dynamic Coverage Enhancement for Object Tracking in Hybrid Sensor Networks Computer Science and Information Engineering Department Fu-Jen Catholic University

2. 2 2 Motivation  Former research about target tracking often consider the data aggregation of target information, and relocate the target position.  We base on the target tracking research, to enhance the target tracking sensing quality by covering the holes appear in the sensor field.  The holes appearance in the sensor field is according to two factors : The deployment of sensor nodes is non-uniform. The sensor nodes ran out of energy.

3. 3 3 Environment description  Our routing problem is based on the GAF protocol, which divides sensor field into multiple grids ， and each grid has one head ， which can communicate to its neighboring head directly. Grid head

4. 4 4 Basic concept  When monitor region exists holes, we want to find sufficient mobile sensor nodes to cover these holes in the monitor region.  The scope of mobile sensor nodes request is mobile sensor’s maximum moving distance. Sensor field Mobile sensor nodes maximum moving distance. Request region

5. 5 5 Working flow When a target enters sensor field and has been detected Forming a monitor region in the sensor field Leader selection Coverage position decision Forming guard region and outer region in the sensor field and request redundant mobile nodes Mobile nodes dispatching decision 1 22 3 4567 8

6. 6 6 Forming monitor region Monitor region Sensing circle

7. 7 7 Leader selection Monitor region grid head leader Sensor node

8. 8 8 Circle covering

9. 9 9 Static sensor nodes union

10. 10 Ray casting algorithm

11. 11 Information gathering 3 11 2 Requirement for number of mobile sensor nodes Number of mobile sensor nodes can support

12. 12 Forming guard and outer region  Conservation scheme  Prediction scheme  both schemes divide the request region into monitor region, guard region, and outer region.  mobile nodes support rule : monitor region and guard region: it can only support the redundant mobile nodes. outer region : it can support all mobile nodes within the outer region.

13. 13 Conservation scheme Monitor region Guard region Outer region holes Mobile node ex

14. 14 Prediction scheme Monitor region Guard region Outer region

15. 15 Conservation scheme Monitor regionGuard regionOuter region back

16. 16 Mobile nodes dispatching 3 3 1 2 1 1 2 21 13 Requirement for number of mobile sensor nodes Number of mobile sensor nodes can support

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