Extreme Networked Systems: Large Self-Organized Networks of Tiny Wireless Sensors David Culler Computer Science Division U.C. Berkeley Intel Berkeley

8/8/2001EECS Visions2 Emerging Microscopic Devices CMOS trend is not just Moore’s law Micro Electical Mechanical Systems (MEMS) –rich array of sensors are becoming cheap and tiny Imagine, all sorts of chips that are connected to the physical world and to cyberspace! LNA mixer PLL baseband filters I  Q  Low-power Wireless Communication

8/8/2001EECS Visions3 Disaster Management Circulatory Net What can you do with them? Embed many distributed devices to monitor and interact with physical world Network these devices so that they can coordinate to perform higher-level tasks. => Requires robust distributed systems of hundreds or thousands of devices. Habitat Monitoring Condition-based maintenance

8/8/2001EECS Visions4 Getting started in the small 1” x 1.5” motherboard –ATMEL 4Mhz, 8bit MCU, 512 bytes RAM, 8K pgm flash –900Mhz Radio (RF Monolithics) ft. range –ATMEL network pgming assist –Radio Signal strength control and sensing –I2C EPROM (logging) –Base-station ready (UART) –stackable expansion connector »all ports, i2c, pwr, clock… Several sensor boards –basic protoboard –tiny weather station (temp,light,hum,prs) –vibrations (2d acc, temp, light) –accelerometers, magnetometers, –current, acoustics

8/8/2001EECS Visions5 A Operating System for Tiny Devices? Traditional approaches –command processing loop (wait request, act, respond) –monolithic event processing –bring full thread/socket posix regime to platform Alternative –provide framework for concurrency and modularity –never poll, never block –interleaving flows, events, energy management –allow appropriate abstractions to emerge

8/8/2001EECS Visions6 Appln = graph of event-driven components RFM Radio byte Radio Packet UART Serial Packet ADC Tempphoto Active Messages clocks bit byte packet Route map routersensor appln application HW SW Example: ad hoc, multi-hop routing of photo sensor readings

8/8/2001EECS Visions7 Pushing Scale

8/8/2001EECS Visions8 Re-explore networking Fundamentally new aspects in each level –encoding, framing, error handling –media access control –transmission rate control –discovery, multihop routing –broadcast, multicast, aggregation –active network capsules (reprogramming) –security, network-wide protection New trade-offs across traditional abstractions –density independent wake-up –proximity estimation –localization, time synchronization New kind of distribute/parallel processing

8/8/2001EECS Visions9 Larger Challenges Security / Authentication / Privacy Programming support for systems of generalized state machines –language, debugging, verification Simulation and Testing Environments Programming the unstructured aggregates Resilient Aggregators Understanding how an extreme system is behaving and what is its envelope –adversarial simulation Constructive foundations of self-organization

8/8/2001EECS Visions10 To learn more

8/8/2001EECS Visions11 Characteristics of the Large Concurrency intensive –data streams and real-time events, not command-response Communications-centric Limited resources (relative to load) Huge variation in load Robustness (despite unpredictable change) Hands-off (no UI) Dynamic configuration, discovery –Self-organized and reactive control Similar execution model ( component-based events) Complimentary roles (eyes/ears of the grid) Huge space of open problems...and Small