Monarch

Adaptive Sensor Network Architecture

Overview - what is Sensor Stack
Contact Person - Santashil PalChaudhuri
Publications - Papers
Talks - Selected Presentation Slides
Related Research - Past and current projects that have similar goals

Overview

Sensor networks have emerged as a promising tool for monitoring (and possibly actuating) the physical world, utilizing self-organizing networks of battery-powered wireless sensors that can sense, process and communicate. In sensor networks, energy is a critical resource, while applications exhibit a limited set of characteristics. Thus, there is both a need and an opportunity to optimize the network architecture for the applications in order to minimize resource consumed. The requirements and limitations of sensor networks make their architecture and protocols both challenging and divergent from the needs of traditional Internet architecture.

Many applications, such as large-scale collaborative sensing, distributed signal processing, and distributed data assimilation require sensor data to be available at multiple resolutions, or to allow fidelity to be traded-off for energy efficiency. I proposed the design of an adaptive cross-layered Sensor Network Architecture -- called COMPASS -- for enabling multi-scale collaboration and communication. COMPASS enables scalability, localization and resolution-tuning, while simplifying application design by providing communication abstractions. Together with a Rajnish Kumar, I characterized the unique design requirements for sensor network architecture and proposed SensorStack as a suitable architecture for sensor networks. SensorStack enables cross-layering using a notification service, adaptability of the protocols to application-specific needs and a communication abstraction for data-centric communication. I then designed routing, scheduling and synchronization protocols to take advantage of the cross-layering and adaptivity enabled by SensorStack.

I proposed a routing protocol, which is a hierarchical overlay to handle aggregation, dissemination, and multiple resolution. This self-organizing network hierarchy adapts to align with the data communication for increased efficiency. To simplify application design, I provide a set of Network Programming Interfaces to abstract the details of low-level communication and implement these interfaces efficiently in the network. For this multi-scale architecture, I then proposed a medium access scheduling protocol, which takes advantage of sensor network application characteristics - periodic nature of communication, limited communication abstractions, and fusion function techniques - to improve energy-efficiency. The scheduling uses a token-passing approach to provide collision-free neighborhoods for apriori known traffic, as well as provides contention-based access period for event-driven traffic. Then I provided a clock synchronization protocol which is adaptive to the need of the applications, by providing the synchronization specified by the applications at any specific time. I derived expressions to convert service specifications (maximum clock synchronization error and confidence probability) to actual protocol parameters (minimum number of messages and synchronization interval).

Publications

Talks

Related research