WMNL Sensors Deployment Enhancement by a Mobile Robot in Wireless Sensor Networks Ridha Soua, Leila Saidane, Pascale Minet 2010 IEEE Ninth International Conference on Networks (ICN) (31%)

Outline  Introduction  Definition of the Problem  Goals  Assumptions  The Proposed Solution  Performance Evaluation  Conclusion

Introduction  WSN deployment  Full coverage (Monitoring Quality)  Minimal number of sensor nodes (cost)  Random Deployment  Coverage Hole  A large number of sensor nodes (hardware cost)

Introduction  Mobile Sensors  Mobility overcomes hole problem  Hardware Cost  Robot Deployment  Regularly deploy static sensor nodes  Easy to obtain full coverage by using minimal number of static sensors  Low hardware cost  Easy and Simple

Definition of the Problem

Goals  This paper proposes a Sensors Deployment Enhancement by a Mobile Robot mechanism for  improve sensing coverage  connectivity of monitored area

Assumptions  Our contribution makes the following assumptions:  Homogenous sensor nodes are randomly deployed in a wide sensor field. One hop communication is used for data transmission and multi hop communication for distant sensors.  The number of sensors is quite sufficient to cover the target field.  Each sensor has no motion capability.  Each sensor is aware of its location, using GPS or another technique.  Each sensor node is aware of its available energy.  The communication range is at least twice of the sensing range.

The Proposed Solution 1.Grid construction Process 2.Grid head selection 3.Discovery and initialization 4.Selection of redundant sensors 5.Healing the coverage holes

The Proposed Solution 1.Grid construction Process Grid construction process

The Proposed Solution 2.Grid head selection  existence of holes  redundant sensors based on their locations

The Proposed Solution 3.Discovery and initialization The Hungarian method

The Proposed Solution 4.Selection of redundant sensors  The robot must fill its stock with redundant sensors to place them in grids that suffer from sensor’s lack without exceeding robot’s capacity.  In this section the problem we focus on is similar to a well known combinatory optimization problem, the Knapsack problem.  We want to maximize the gain and meet the condition :  The robot sorts the list of redundant grids and choose the most efficient redundant grids until having its stock full.

The Proposed Solution 5.Healing the coverage holes  Execution of Kruskal algorithm c b d a e c b d a e a b c e d

Experimental Evaluation SimulatorCastalia (version 2.0) Sensor nodes55,120,400,650 Area 20m × 20m to 100m × 100m Sensing range r s 8m

Experimental Evaluation  Moving distances

Experimental Evaluation  Moving distances

Experimental Evaluation  Coverage quality

Conclusions  This paper addressed the problem of redeploying sensors in a target field to maximize the sensing coverage.  Our approach must optimize the motion of a mobile robot in the target field on which the sensors are deployed so that holes are healed and field’s coverage and connectivity are achieved.

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