TTDD: A Two-tier Data Dissemination Model for Large-scale Wireless Sensor Networks

Ajit Pawar

ID: 2012H140035G

BITS PILANI KK BIRLA GOA CAMPUS

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Outline

Application scenario

Two-tier query and data forwarding

Grid Maintenance

Conclusion

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Application scenario

Excessive PowerConsumption

Increased WirelessTransmissionCollisions

State MaintenanceOverhead

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Challenges

Deployment in large scale Fully distributed without global knowledge

Large numbers of sources and sinks

Unexpected sensor node failures

Sink mobility Frequent location updates

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TTDD Basics

Sensor initiated

Grid formation

Source proactively builds a grid structure

Divides the plane into grid of cells

Each cell size a x a

Data announcement messages from source

Greedy Geographic forwarding

Every DN keeps the information about its

upstream DN

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Two –tier forwarding model

Two-tier forwarding model

Query and data forwarding

Trajectory forwarding

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Query n Data forwarding

Query forwarding

Sink broadcasts query within the cell

Selects the nearest dissemination node

Dissemination node forwards the same query towards sink

Query aggregation in case of more than one sink asks for the same data

Data forwarding

Follows the same path as query

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TTDD Basics

Source

Dissemination Node

Sink

Data Announcement

Query

Data

Immediate DisseminationNode

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Trajectory forwarding

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TTDD Multiple Mobile Sinks

Source

Dissemination Node

Data Announcement

Data

Immediate DisseminationNode

TrajectoryForwarding

Source2

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Grid Maintenance

Issues: Handle unexpected dissemination node failures

Efficiency

Solutions: Source sets the Grid Lifetime in Data

Announcement

DN replication: each DN recruits several sensor nodes from its one-hop neighbor, replicates the location of the upstream DN

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Grid Maintenance

When this dissemination node fails, messages from its downstream DN that needs data will stop at one of these recruited nodes

Grid maintenance is triggered on-demand by on-going query and data flows

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Grid Maintenance

Source

Dissemination Node

Data

Immediate DisseminationNode

X

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limitations

Sink mobility speed

Limit on the mobility of stimulus

Waste of resources in regions where sinks never roam, in case of Even Distribution

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Conclusion

Provides scalable and efficient data delivery to multiple mobile sinks

Exploit sensor nodes being stationary and location-aware

Construct & maintain a grid structure with low overhead

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Thank you

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