Dynamic Coverage Enhancement for Object Tracking in Hybrid

Sensor Networks

Computer Science and Information Engineering Department

Fu-Jen Catholic University

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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.

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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

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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

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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 fieldand request redundant mobile nodes

Mobile nodes dispatching decision

1

2 2

3

456 7

8

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Forming monitor region

Monitor region

Sensing circle

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Leader selection

Monitor region

grid head

leader

Sensor node

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Circle covering

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Static sensor nodes union

1010

Ray casting algorithm

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Information gathering

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1 1

2

Requirement for numberof mobile sensor nodesNumber of mobile sensor

nodes can support

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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.

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Conservation scheme

Monitor region

Guard region

Outer region

holes

Mobile node ex

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Prediction scheme

Monitor region

Guard region

Outer region

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Conservation scheme

Monitor region

Guard region

Outer region

back

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Mobile nodes dispatching

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3

1

2

1

1

2

2 1

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Requirement for numberof mobile sensor nodes

Number of mobile sensor nodes can support

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