Sensornets. A Building Block Approach to Sensornet Systems

Transcription

1 Sensornets A Building Block Approach to Sensornet Systems Dutata, P., Taneja, J., Jeong, J., Jiang, X., & Culler, D. University of California, Berkely April 9, 2012 Azfar Khandoker Ryan Miller

2 What is a sensornet? "...spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, humidity, motion or pollutants and to cooperatively pass their data through the network to a main location." (Wikipedia)

3 Background Traditionally: Tight coupling between embedded sensor networks and their applications Proposal: Goals Support prototype, platform, and production Two-layer hierarchy Modules Carriers

4 Goals Prototype - early modeling Platform - establish long-term capabilities Production - commercialization

5 Modules and Carriers Modules Building Block Approach Mote Carriers

6 Core Module Microcontroller IEEE radio Flash memory Small, inexpensive design Epic core module

7 Radio Early mote designs used a wide variety of radio interfaces New trend - IEEE standard "Wireless personal area networks (WPANs) are used to convey information over relatively short distances. Unlike wireless local area networks (WLANs), connections effected via WPANs involve little or no infrastructure. This feature allows small, power-efficient, inexpensive solutions to be implemented for a wide range of devices." Heile, R. F. (2003) New York, NY: The Institute of Electrical and Electronics Engineers, Inc.

8 Quiz Break Fluttershy wants to know, which of these is not a component of the core module? A. Microcontroller B. IEEE b Radio C. IEEE Radio D. Flash memory

9 Flash Dual RAM buffers Connection to MCU; two designs Same bus as Radio Different bus Write-protect line; two schools of thought Make flash write-protected Allow flash to be reprogrammed

10 Design Questions How should the microcontroller communicate with the radio? Serial Peripheral Interface (SPI) bus What form factor and connector interface should the module use? Perimeter Pads

11 Evaluation Radio wakeup time Epic: 629 ± 3 microseconds Telos: 619 ± 3 microseconds Sleep current (3V) Epic: 7 microamps Telos: 6 microamps Radio reception

12 Radio Reception Performance

13 Quiz Break Lyra wants to know, how does the MCU communicate with the flash memory? A. GPIO line B. SPI bus C. Capacitor

14 Peripheral Modules Modules: Core Storage USB

15 Prototyping "Try it and see" demonstrate important capability enable data collection reduce implementation risk through existence proof Development board

16 Prototyping "Try it and see" demonstrate important capability enable data collection reduce implementation risk through existence proof Development board Debugging

17 Discussion Reuse at the level of Computer-Aided Design (CAD) parts and schematics Reuse at CAD parts/schematic level Encourage greater reuse Little overlap in electronic parts between modules and carriers Module designs vs. carrier board designs

18 Quiz Break Rainbow Dash wants to know, what board was developed for debugging? A. Development board B. Interface board C. Breakout board

19 Application 1 Flying Robot Navigation Dartmouth (2005) Corke, P., Peterson, R., & Rus, D. (2005) Networked Robots: Flying Robot Navigation Using A Sensor Net. Robotics Research,

20 Application 1 TinyOS implementation ATMega128 CPU with 4K 4 MHz 50 Kbps RF tranceiver on every mote Instantaneous position calculated using: GPS position of helicopter: pi = (xi, yi) "Strongest" sensor position received so far

21 Application 1

22 Application 2 Sensornets and Security Sensornets typically use symmetric encryption Less computation, but More difficult key management Public Key Encryption for Sensornets

23 Application 2 Public Key Encryption for Sensornets Elliptic Curve Cryptography approach (2011) Rather than factoring large primes, use the curvature of random ellipses Wang, H., Sheng, B., Tan, C. C., & Li, Q. (2011) Public-key based access control in sensornet. Wireless Networks, 17,

24 Quiz Break Derpy wants to know, which factors might inhibit a sensornet's performance? A. Network congestion B. Microcontroller performance C. Limited memory D. All of the above

25 Conclusion Sensornets made up of motes Small, Inexpensive Wireless radio Low power consumption Motes face several design decisions Flash memory Radio capability Peripheral Modules

26 Conclusion Importance of Prototyping "Try it and see" attitude Development board Breakout board Sensornets have wide range of applications Navigation, Medical, Civil Engineering Overlap with other fields, such as security computer architecture algorithms

27 Questions? My Little Pony characters Hasbro, Inc.