Presentation by: Drew Wichmann Paper by: Samer Hanoun and Saeid Nahavandi 1.

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Dynamic Route Construction for Mobile Collectors in Wireless Sensor NetworksPresentation by: Drew WichmannPaper by: Samer Hanoun and Saeid Nahavandi

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Wireless Sensor Networks (WSNs)

Set of small nodesDistributed in spaceMonitor conditionsBuilt with

Transceiver Microcontroller Sensor Energy source

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Power Consumption

Biggest Issue

Forwarding

Bottlenecking Unbalanced distribution

Solution Mobile Sinks

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Mobile Sinks

Mechanical data carrier Robot Unmanned Aerial Vehicle (UAV)

Physically approach sensorsRequires routes

Random Static Dynamic

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Problem Formulation

Assumptions Known locations Sensor nodes stationary Uniformly distributed Sleep when full Mobile collector▪ Sufficient energy▪ Sufficient memory

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Problem Formulation (Continued)

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Route Construction Algorithm

1. Build a fully connected graph G(V,E) of all sleeping sensors

2. Select a vertex r (center of sensing field) to be a root vertex

3. Compute a minimum spanning tree T for G from root r

4. Let L be the list of vertices visited in a DFS on T

5. Generate the Hamiltonian cycle H that visits the vertices in the order L

6. Follow the Hamiltonian cycle H as the constructed route

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Example

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Build connected graph

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Select root

Root r

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Compute Minimum Spanning Tree

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Create List

ABFGCDE

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Find Hamiltonian Cycle

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Follow Hamiltonian Cycle

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Simulation

Parameters 150 Sensors (uniformly distributed)

100m x 100m area

1 KB buffer

50000 time units

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Simulation Parameters (continued)

Events occur at centerRi = i * R1

R1 = 10msensingrangei =

[ baserate * (i-1) + 1, baserate * i ]

baserate = 2 seconds

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Results

20 different independent networksCompared with closest neighborMetrics

Sleeping Time Number of Sleeping Sensors Sleeping Time per Request Distance Travelled per Request

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Results

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Results

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Conclusion

No dependency on data generation rates

Minimize sleeping times

Better performance than closest neighbor

Shows effect of speed and number of collectors

Future work Cooperation between collectors Real-time requests