Introduction to Wireless Sensor Networks 1 Wireless Sensor

Introduction to Wireless Sensor Networks 1

Wireless Sensor Networks (WSNs) • Many simple nodes with sensors deployed throughout an environment Sensing + CPU +Radio = Thousands of Potential Applications Ref. [Introduction_1] p. 102 - 105 2

WSN Applications • Indoor/Outdoor Environmental Monitoring – Habitat Monitoring – Structural Monitoring – Precision Agriculture • Triggered Events – Detection/Notification • Military Applications – Battlefield Surveillance • Health Monitoring Ref. [Introduction_1] p. 102 - 105 3

Some Existing Applications • Create a macroscope – Deployed on Redwood Trees – Great Duck Island – Tracking zebra – Monitor volcanic eruptions 4

• • Operational Challenges of Wireless Sensor Networks Energy Efficiency Limited storage and computation Low bandwidth and high error rates Errors are common – Wireless communication – Noisy measurements – Node failure are expected • Scalability to a large number of sensor nodes • Survivability in harsh environments • Experiments are time- and space-intensive Ref. [Introduction_1] p. 102 - 105 5

Characteristics of Wireless Sensor Networks • Limited in – – – Energy Computation Storage Transmission Range Bandwidth • Characteristics – – Self-organize Random Deployment Cooperating Local Computation Ref. [Introduction_1] p. 102 - 105 6

Enabling Technologies Embed numerous distributed devices to monitor and interact with physical world Embedded Network devices to coordinate and perform higher-level tasks Networked Exploit collaborative Sensing, action Control system w/ Small form factor Untethered nodes Sensing Tightly coupled to physical world Exploit spatially and temporally dense, in situ, sensing and actuation 7

Hardware Constraints • Power, size, and cost constrained – Small memory – Slow clock cycles of microcontroller 8

One Example Sensor Node - Mica. Z Mote • • Developed at UC Berkeley Fabricated by Crossbow Inc. Integrated Wireless Transceiver CPU – MPR 2400, based on Atmega 128 L – 8 MHz • Memory – 4 KB of primary memory (SRAM) – 128 KB of program space (ROM) – 512 KB Flash Memory • Transmit Data Rate – 250 kbps • Transmission Range – Outdoor: 75 m – 100 m – Indoor: 20 m - 30 m • Frequency Band – 2. 4 GHz http: //www. xbow. com/Products/pr oductdetails. aspx? sid=164 9

I/O Sub-System • The I/O subsystem interface consists of a 51 -pin expansion connector eight analog lines, eight power control lines, three pulse-width-modulated lines, two analog compare lines, four external interrupt lines, an I 2 C-bus from Philips Semiconductor, an SPI bus, a serial port, a collection of lines dedicated to programming the microcontrollers. [hardware_1] Page 17 expansion connector – – – – – 10

One Example Sensor Board - MTS 310 http: //www. xbow. com/Products/pr oductdetails. aspx? sid=177 11

One More Example of Sensor Board MTS 400/420 • Besides the functions of MTS 300, it mainly adds GPS functionality • Example GPS Reading – http: //firebug. sourceforge. net/gps_tests. htm http: //www. xbow. com/Products/pr oductdetails. aspx? sid=177 12

Hardware Setup Overview 13

Programming Board (MIB 520) http: //www. xbow. com/Products/pr oductdetails. aspx? sid=227 14

Telos. B • http: //www. xbow. com/Products/productdetails. aspx? sid=252 15

Telos. B Architecture • [Energy_1]: Figure 2 16

Typical WSN Platforms Ref: [Tiny. OS_1]: Table 1 17

One Proposed WSN Functional Layer Decomposition • Ref: Fig. 1. 1 of J. Polastre Dissertation: http: //www. polastre. com/papers/polastre-thesisfinal. pdf 18

Architecture to Build WSN Applications • Ref: Fig. 2. 1 of J. Polastre Dissertation: http: //www. polastre. com/papers/polastre-thesis-final. pdf 19