The Platforms enabling Wireless Sensor Networks Hill, Horton, Kling, Krishnamurthy CACM, June 2004

Goals Explore the different sensor network platforms (4) Since these devices often work together in the real world, also explore their architectural similarities and core differences Recent progress in hardware and possible future capabilities

Platform Classes Not all nodes are the same! Tiered architecture. Consider an example: Advanced Security system. Includes: 1.Simple battery powered sensors for motion, window breakage etc. 2.Advanced sensors like cameras, acoustic, chemical sensors

Platform classes Simple sensors have a specific function and require long term battery operation Also – minimal processing and bandwidth requirements Complex Acoustic, Video etc require more computation and communication resources Often also require to be ‘plugged’ in

Platform classes A third sensor class is “Mini-Motes” Low cost security tags for asset management, personnel tracking etc Highly integrated and very inexpensive ‘Smart-dust’ Finally – One or more endpoints containing database or aggregation capabilities – Gateway nodes

Hierarchical deployment of platforms

Operating characteristics of the node classes

Examples Asset tags – Spec node (Berkley) General class sensing – Berkley motes (Mica2) High bandwidth sensing- iMote (Intel) Gateway – Stargate platform (Intel, Crossbow)

Architectural Differences A lot of similarity between the four classes despite significant capability differences This is because of the requirement that Network support is seamless and self configuring Core differences come from optimizations in power for certain classes of

Architectural Differences Major difference between sensors and more traditional computers/PDA’s is the emphasis on power management To manage power efficiently, each subsystem is powered individually TinyOS controls activity and power state of various subsytems.

Architectural Differences Sensor platforms give applications direct, fine grained control over the hardware Traditional stacks inefficient 3 pronged approach: - General purpose component framework that eliminates layering - Hardware func exposed to applications/middleware - Virtualization/ Abstraction to write sensor applications

Architectural Differences

Platform Roadmap Hardware Progression – Moore’s law insures increase in performance for a given power budget. Mica2 is 8 times more memory, bandwidth than its predecessor Rene for same cost New CMOS radios for low data rates, and using low power

Platform Roadmap Software and Interface standards determines what radio hardware to use Zigbee determines the content of messages

Conclusion Surveyed a variety of platforms. Realization that real networks employ a variety of these.