Extreme Networked Systems: Large Self-Organized Networks of Tiny Wireless Sensors

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Extreme Networked Systems Large Self-Organized
Networksof Tiny Wireless Sensors

• David Culler
• Computer Science Division
• U.C. Berkeley
• Intel Research _at_ Berkeley
• www.cs.berkeley.edu/culler

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Emerging Microscopic Devices

• CMOS trend is not just Moores 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!

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What can you do with them?
Disaster Management

• Embed many distributed devices to monitor and
  interact with physical world
• Network these devices so that they can coordinate
  to perform higher-level tasks.
• gt Requires robust distributed systems of
  hundreds or thousands of devices.

Habitat Monitoring
Condition-based maintenance
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Getting started in the small

• 1 x 1.5 motherboard
• ATMEL 4Mhz, 8bit MCU, 512 bytes RAM, 8K pgm flash
• 900Mhz Radio (RF Monolithics) 10-100 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

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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

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Appln graph of event-driven components
Route map
router
sensor appln
application
Active Messages
Radio Packet
Serial Packet
packet
Temp
photo
SW
HW
UART
Radio byte
ADC
byte
Example ad hoc, multi-hop routing of photo
sensor readings
clocks
RFM
bit
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Pushing Scale
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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

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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

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To learn more

• http//www.cs.berkeley.edu/culler
• http//tinyos.millennium.berkeley.edu/
• http//webs.cs.berkeley.edu/
• http//ninja.cs.berkeley.edu/

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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