System architecture directions for networked sensors

Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. They ca n be deeply embedded in the physical world and spread throughout our enviro nment like smart dust. The missing elements are an overall system architect ure and a methodology for systematic advance. To this end, we identify key requirements, develop a small device that is representative of the class, d esign a tiny event-driven operating system, and show that it provides suppo rt for efficient modularity and concurrency-intensive operation. Our operat ing system fits in 178 bytes of memory, propagates events in the time it ta kes to copy 1.25 bytes of memory, context switches in the time it takes to copy 6 bytes of memory and supports two level scheduling. The analysis lays a groundwork for future architectural advances.