A Hierarchical Scheme for Data Aggregation in Sensor networks

Bin Zhou*; Lek Heng Ngoh**; Bu Sung Lee*; Cheng Peng Fu*;*School of Computer Engineering Nanyang Technological University

**Networking Department Institute for Infocomm Research

IEEE International Conference Networks (ICON), 2004

Outline

Introduction Related work Hierarchical Scheme Performance Evaluation Conclusion

Introduction - background

Data transmission over sensor networksLocation-centric protocol

TTDD: Two-tier Data Dissemination in Large-scale Wireless Sensor Networks

Data –centric protocol Directed Diffusion for Wireless Sensor Networking

Introduction - motivation and goals

MotivationHierarchical scheme with enhancement on Dir

ected Diffusion

GoalsSave transmission energyHigher reliability

Related work

Title : Directed Diffusion for Sensor Networks Author : Chalermek Intanagonwiwat,

Ramesh Govindan, Deborah Estrin IEEE/ACM Transactions on Networking(2003

)

Related work – Directed Diffusion for Sensor Networks

Data-centric dissemination Request driven

Sinks place requests as interests Sources are eventually found and satisfy interests Intermediate nodes route data toward sinks

Reinforcement-based adaptation to the best path Repair

Interests and Gradients

Flooding Interest Gradient specifies both a data rate and a

direction in which to send events

Sink

SourceInterestGradient

Data Propagation

Data flows from the source to the sink along the gradient

Multipath delivery with probabilistic forwarding.

Multipath delivery with selective quality along different paths.

Sink

SourceDataGradient

Reinforcement

Reinforcement to single path delivery Selects an empirically low delay path

Sink

SourceDataGradient

Reinforcement

Multiple sources

Sink

Source DataGradient

Reinforcement

Source

Repair

Sink

Source

Sink

SourceDataGradient

Reinforcement

Related work – Directed Diffusion for Sensor Networks

AdvantageProvide robust, scalable and energy efficient

sensor data dissemination mechanism Shortcoming

Data aggregation is not optimal

Hierarchical scheme - overview

Hierarchy construction Attribute establishment Data aggregation Data distribution

Hierarchical scheme - Hierarchy construction

Flood interest message over sensor networks Each node (level N) knows about all its parents

and children (level N+2).

1 12 2

2

32 32

Level 0sink

Level 1

Level 2

Level 3source source

source

source source

source

Hierarchical scheme - Attribute establishment

When source has the appropriate data, it will send back the exploratory data.

Attribute : number of sources contained in the sub-tree rooted by the node

source source

source

22

2

3

3

source

Hierarchical scheme - Attribute establishment

Reinforcement message : parent informs its children about its own attribute

source

source

22

2

3

3

Hierarchical scheme - Data aggregation

A source receives the reinforcement, it sends out the data.

Child chooses the “alive” parent whose attribute is best.

source

source

22

2

3

3

source

Hierarchical scheme - Data distribution

With multiple sinks, each sink will have an individual hierarchical structure.

Every node stores the information of its parent and children for different sink interests.

source

Sink 1

Sink 2 Sink 3

1 2 3

2 3

3

1

2

Performance Evaluation

ns-2 50-250 nodes are randomly spread in a 160X160

m square field. Radio range : 40m 5 sinks and 5 sources Interest rate of sink : 1 event per 5 seconds Exploratory data rate of source :

1 event per 50 seconds Data rate of source : 2 event/s

Performance Evaluation

Performance Evaluation

Performance Evaluation

20% of the nodes fail randomly

Conclusion

Designed a hierarchical scheme for data aggregation in sensor networksenergy saving transmission efficiencyhigher reliability