1. Mica: A Wireless Platform for Deeply Embedded Networks Jason Hill and David Culler Presented by Arsalan Tavakoli

2. Requirements for Wireless Embedded Networks Platform Low power consumption Protocol processing must be optimized for ultra-low power consumption, not high data rates No reliance on pre-deployed infrastructure network Must be suited to wide-variety of applications

3. Conventional Wireless Platforms Cell Phones Expensive, single application, pre-deployed infrastructure Wireless Ethernet (802.11b) High power consumption Bluetooth Master-slave format with 8 max connections limits large, efficient deployments

4. Mica Platform Runs TinyOS operating system Facilitates cross-layer optimization through interconnected interfaces Does not require use of pre-defined protocols Minimal power consumption

5. Mica Sensor Node

6. Mica Architecture Diagram

7. Atmel Microcontroller Runs at 4 Mhz with 4 MIPS 128KB flash program memory 4KB static RAM One external universal asynchronous receiver transmitter (UART) One serial (SPI) port

8. TR1000 Radio Transceiver Communication rates up to 115 Kb/s Unobstructed communication range of approximately 200 feet Operating System: Controls radio transmission strength Can sense strength of the receive signal

9. Expansion Connector 51-pin Connector for attaching sensor boards to increase sensing capabilities: Temperature Barometric Pressure Magnetic Fields Light Passive Infrared Frequency (Motion) Acoustic

10. Other Components Coprocessor – Allows for wireless dynamic reprogramming DS2401 – Provides unique ID 4Mb External Flash – Stores data logs and temporarily holds program images Dc-Dc Boost Converter – Provides constant 3.3V power supply

11. TinyOS Operating System Designed at UC Berkeley specifically for sensor networks Event-based operating system Component-based structure allows application customization No blocking or waiting

12. Packet Transmission and Reception

13. Hardware Accelerators Buffer Accelerator Shared memory buffer between bit-parallel data path and bit-serial radio channel Synchronization Accelerator Captures exact timing of incoming packet (within one clock cycle) Information available to application software

14. RF Wake-Up Ultralow-power Network Wake-Up Signal Nodes turn off radios to conserve energy Wake-up call is long RF pulse Nodes wake up periodically to check for wake-up signal

15. Time Synchronization Primitive time synchronization scheme discussed Allows pair-wise synchronization Sender stamps packet as it is being transmitted Receiver stamps packet as it is received, and computes difference

16. Localization RF Signal Strength falls off with distance With knowledge of sender’s transmit power level, receiver can approximate distance Localization through acoustic pulses

17. Application Classes Applications with low-duty cycle, low data-rate, long latency, static topology, and long expected lifetime Applications with highly dynamic sense- and-control networks with high data- rates, latency limits, and highly mobile nodes