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This presentation discusses the problem of matching data dissemination algorithms to application requirements. It explores various diffusion routing algorithms and evaluates their effectiveness in addressing application-specific needs. The conclusion highlights the benefits of geographically-scoped queries in larger networks.
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Matching Data Dissemination Algorithms to Application Requirements John Heidermann, Fabio Silva, Deborah Estrin Presented By: Bryan Wong
Outline • Introduction • Problem Description • Diffusion Routing Algorithms • Evaluation • Conclusion
Introduction • Data dissemination algorithms are application specific • Reduces communications costs by replacing communication with computation in the network • As number of protocols and sophistication of applications grows, choice of communication algorithm becomes a problem
Problem Description • How can diffusion address application-specific requirements?
Robustness Requirements • Applications must be robust to change: • Wireless links come and go • Nodes fail or move • How can communication be robust but also efficient for many different applications?
Application Requirements • Sensor network applications have different needs • Different traffic patterns (many-to-one, many-to-many, one-to-many, one-to-one) • Different data rates (fixed and variable, frequent and infrequent)
Solution • Match routing algorithms to application requirements
Multiple Diffusion Routing Algorithms • Two-Phase Pull Diffusion • One Phase Pull Diffusion • Push Diffusion • GEAR
Two-phase pull diffusion • Initial diffusion implementation • Periodically floods data sink’s interests and exploratory data
GEAR • Adds support for geographically scoped queries • If nodes know their locations, then geographic queries can influence data dissemination • Replaces network wide communication with geographically constrained communication
Push Diffusion • Reverses the roles in the publish/subscribe API • Floods only exploratory data messages
One-phase pull diffusion • Subscriber based system that avoids one of the two phases of flooding in two-phase pull • Only floods interests • No exploratory messages
Sample Applications • Push reduces message count by ~60% compared to two phase pull
Sample Applications • GEAR reduces message count by ~40%
Systematic Evaluation • One-phase pull is best with many sources, few sinks • Push works best with many sinks and few sources
Conclusions • The break even point between the two algorithms depends upon specific control message frequency as well as application data rates • For networks with more than a few dozen nodes, the benefits of geographically-scoped queries can outweigh other algorithmic choices
References • http://www.cens.ucla.edu/Education/RR_Posters/Research%20Review/015_Silva.pdf