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Chapter 1:Chapter 1:IntroductionIntroduction

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Internet, Internet, Satellite, UAVSatellite, UAV

Sink

Sink

TaskManager

WIRELESS SENSOR NETWORK (WSN) ARCHITECTUREWIRELESS SENSOR NETWORK (WSN) ARCHITECTURE

I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cayirci, “Wireless Sensor Networks: A Survey”, Computer Networks (Elsevier) Journal, March 2002.

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CHARACTERISTICS OF WSNsCHARACTERISTICS OF WSNs Envisioned to consist of very large number of nodes, Envisioned to consist of very large number of nodes,

often in the order of thousandsoften in the order of thousands Nodes need to be close to each otherNodes need to be close to each other Densities as high as 20 nodes/mDensities as high as 20 nodes/m33

Asymmetric flow of information, from sensor nodes to Asymmetric flow of information, from sensor nodes to sinksink

Communications are triggered by queries or eventsCommunications are triggered by queries or events Limited amount of energy (in many applications, it is Limited amount of energy (in many applications, it is

impossible to replace or recharge)impossible to replace or recharge)

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CHARACTERISTICS OF WSNsCHARACTERISTICS OF WSNs Mostly static topologyMostly static topology Low costLow cost, size, and weight per node, size, and weight per node Prone to failuresProne to failures More use of broadcast communications instead of More use of broadcast communications instead of

point-to-pointpoint-to-point Nodes do not have a global ID such as an IP addressNodes do not have a global ID such as an IP address The security, both on physical and communication The security, both on physical and communication

level, is more limited than in classical wireless level, is more limited than in classical wireless networks networks

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DIFFERENCES FROM AD-HOC DIFFERENCES FROM AD-HOC NETWORKSNETWORKS

Number of sensor nodes can be several orders of magnitude Number of sensor nodes can be several orders of magnitude higherhigher

Sensor nodes are densely deployed and are prone to failuresSensor nodes are densely deployed and are prone to failures

The topology of a sensor network may change frequently due The topology of a sensor network may change frequently due to node failure and node mobilityto node failure and node mobility

Sensor nodes are limited in power, computational capacities, Sensor nodes are limited in power, computational capacities, and memoryand memory

May not have global ID like IP addressMay not have global ID like IP address

Need tight integration with sensing tasksNeed tight integration with sensing tasks

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Power UnitPower Unit ANTENNAANTENNA

Sensor ADCSensor ADCProcessorProcessor

MemoryMemoryTransceiverTransceiver

Location Finding SystemLocation Finding System MobilizerMobilizer SmallSmall Low powerLow power Low bit rateLow bit rate High density High density Low cost (dispensable)Low cost (dispensable) AutonomousAutonomous AdaptiveAdaptive

SENSING UNIT PROCESSING UNIT

Sensor Node HardwareSensor Node Hardware

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Sensor Node HardwareSensor Node Hardware Two main componentsTwo main components

Base (Processor + Transceiver)Base (Processor + Transceiver)

Sensor BoardSensor Board

Base + Sensor Board(s) = Sensor NodeBase + Sensor Board(s) = Sensor Node

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25 lb, 19.5 x 5.5 x 16 inch

~ 64 W

~ $6K (today)

160 KB Floppies

16-256 KB RAM

4.77 MHz

Original IBM PC (1981)

0.5 oz, 2.25 x 1.25 x 0.25 inch

~14 mW

~ $125

512 KB Flash

128 KB RAM

8 MHz

MICAZ Mote (2005)

Sensor Node FeaturesSensor Node Features

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Sensor Motes TimelineSensor Motes Timeline

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Rockwell WINS

Smart Dust

JPL Sensor Webs

Dust

Examples for Sensor NodeExamples for Sensor Nodess

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MICA Mote

Rene Mote

weC Mote

Dot MoteExamples for Sensor NodeExamples for Sensor Nodess

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Current Platforms: 1st GenerationCurrent Platforms: 1st Generation Mica2DOT (2003)Mica2DOT (2003)

16Kb program mem16Kb program mem RFM TR1000 (CSMA/ASK)RFM TR1000 (CSMA/ASK) Lightweight and small Lightweight and small

Mica2 & Cricket platform (2003)Mica2 & Cricket platform (2003) 128Kb program mem128Kb program mem ChipconCC1000 (CSMA/FSK)ChipconCC1000 (CSMA/FSK) 40Khz Ultrasounders (Cricket only)40Khz Ultrasounders (Cricket only)

MicaZ (2004) & Telos (2005)MicaZ (2004) & Telos (2005) 802.15.4/Zigbee stack802.15.4/Zigbee stack Spread Spectrum radio handles multipath betterSpread Spectrum radio handles multipath better Integrated antenna (Telos only) Integrated antenna (Telos only)

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Current Platforms: 2nd GenerationCurrent Platforms: 2nd Generation Imote (2003) & Imote2 (2007)Imote (2003) & Imote2 (2007)

Higher processing powerHigher processing power

Bluetooth & 802.11 capable (Imote2 only)Bluetooth & 802.11 capable (Imote2 only)

Stargate (2005) & Stargate 2.0 Stargate (2005) & Stargate 2.0

Pentium class processor Pentium class processor

Linux OS => easy development (C/C++)Linux OS => easy development (C/C++)

Higher processing capabilities => energy intensiveHigher processing capabilities => energy intensive

802.11 capable802.11 capable

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SENSOR NODE FEATURESSENSOR NODE FEATURESProcessing and StorageProcessing and Storage

Feature Imote (2003)

Mica2 (2003)

MicaZ (2004)

Telos (2005)

Stargate (2005)

Imote2

(2009)

Speed [MHz] 12 8 8 8 400 13-416*

Flash [kB]

(Program)

512 128 128 48 32,000 32,000

Serial Flash [kB]

(Measurement data)

N/A# 512 512 1024 N/A# N/A#

SRAM / EEPROM / SDRAM ‡ [kB]

(Configuration)

64 4 4 10 64,000 256-32,000 ◊

* Multiple processor speed levels# Imote, Stargate, and Imote2 use a single Flash for program and measurement data‡ Imote, Imote2, and Telos use SRAM; Mica2 and MicaZ use EEPROM; Stargate uses SDRAM◊ Imote2 will have different versions, SRAM changes accordingly

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SENSOR NODE FEATURESSENSOR NODE FEATURESCommunication and PowerCommunication and Power

FeatureFeature Imote (2003)Imote (2003) Mica2 (2003)Mica2 (2003) MicaZ (2004)MicaZ (2004) Telos (2005)Telos (2005) ImoteImote22

Radio FrequencyRadio Frequency 2.4 GHz2.4 GHz 300-900MHz300-900MHz 2.4 GHz2.4 GHz 2.4 GHz2.4 GHz 2.4 GHz2.4 GHz

DataRate [kb/s]DataRate [kb/s] 720720 1515 250250 250250 250 (720 250 (720 ΔΔ

/11,000 /11,000 ••))

Power Power

CarrierSense/Rx./Tx.CarrierSense/Rx./Tx. [mA][mA]

15 / 24 / 2415 / 24 / 24 8 / 10 / 278 / 10 / 27 8 / 20 / 188 / 20 / 18 1 / 20 / 181 / 20 / 18 40/20/1840/20/18

PowerSleep PowerSleep [mA][mA]

1-250 1-250 @@ 1919 2727 66 1-100 1-100 @@

Radio RangeRadio Range 32 ft (10 m)32 ft (10 m) 500 ft (150m)500 ft (150m) 300 ft (100m)300 ft (100m) 400 ft (125m)400 ft (125m) 100ft (30m)100ft (30m)

Power sourcePower source AA BatteryAA Battery 2xAA2xAA 2xAA2xAA 2xAA2xAA 3xAAA3xAAA

Δ With external Bluetooth adapter• With external WLAN adapter@ Different sleep levelsStargate communication and power properties depend on the connected module (Mica2,MicaZ sensors or Stargate communication and power properties depend on the connected module (Mica2,MicaZ sensors or WLAN)WLAN)Stargate powered by 5-6V DC or A/C adaptorStargate powered by 5-6V DC or A/C adaptor

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MICAz PlatformMICAz Platform Microprocessor: Atmel ATmega128LMicroprocessor: Atmel ATmega128L

7.3728 MHz clock7.3728 MHz clock 128 kB of Flash for program memory128 kB of Flash for program memory 4 kB of SRAM for data and variables4 kB of SRAM for data and variables 2 UARTs (Universal Asynchronous Receive 2 UARTs (Universal Asynchronous Receive

and Transmit)and Transmit) Serial Port Interface (SPI) busSerial Port Interface (SPI) bus Dedicated hardware I2C busDedicated hardware I2C bus

Radio: Chipcon’s CC2420 (IEEE 802.15.4)Radio: Chipcon’s CC2420 (IEEE 802.15.4) 250 kbit/s250 kbit/s

External serial flash memory: 512 KbExternal serial flash memory: 512 Kb xbow estimates > 100000 samplesxbow estimates > 100000 samples

51-pin expansion connector51-pin expansion connector Eight 10-bit analog I/OEight 10-bit analog I/O 21 general purpose digital I/O21 general purpose digital I/O

User interface: 3 programmable LEDsUser interface: 3 programmable LEDs Powered by two AA batteries Powered by two AA batteries

1850 mAh capacity1850 mAh capacity

Logger Flash

ATMega128LcontrollerAnalog I/ODigital I/O

Freq. Tunable Radio

51-Pin

Exp

ansio

n C

on

nec

tor

Antenna

MMCX connector

LE

Ds

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Telos PlatformTelos Platform

RobustRobust USB interfaceUSB interface Integrated antenna (30m-125m)Integrated antenna (30m-125m) External antenna capability External antenna capability

(~500m)(~500m)

High PerformanceHigh Performance 10kB RAM, 48 KB ROM10kB RAM, 48 KB ROM 12-bit ADC and DAC 12-bit ADC and DAC

(200ksamples/sec)(200ksamples/sec) Hardware link-layer encryptionHardware link-layer encryption

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Telos PlatformTelos Platform Single board philosophySingle board philosophy

Robustness, Ease of use, Lower CostRobustness, Ease of use, Lower Cost Integrated Humidity & Temperature sensorIntegrated Humidity & Temperature sensor

Uses 802.15.4Uses 802.15.4 CC2420 radio, 2.4 GHz, 250 kbpsCC2420 radio, 2.4 GHz, 250 kbps

Motorola HCS08 processorMotorola HCS08 processor Lower power consumption, 1.8V operation, faster wakeup Lower power consumption, 1.8V operation, faster wakeup

timetime 40 MHz CPU clock, 10K RAM; 48K Flash40 MHz CPU clock, 10K RAM; 48K Flash 50m indoor; 125m outdoor ranges50m indoor; 125m outdoor ranges

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SunSPOT PlatformSunSPOT Platform Microprocessor: 32 bit ARM920T coreMicroprocessor: 32 bit ARM920T core

180 MHz clock180 MHz clock 512 kB of Flash for program memory512 kB of Flash for program memory 4 MB of Flash for data4 MB of Flash for data USB ConnectionUSB Connection

Radio: Chipcon’s CC2420 (IEEE 802.15.4)Radio: Chipcon’s CC2420 (IEEE 802.15.4) 250 kbit/s250 kbit/s

3.7V rechargeable 720 mAh lithium-ion battery3.7V rechargeable 720 mAh lithium-ion battery

Software: Squawk VMSoftware: Squawk VM

Fully capable J2ME CLDC 1.1 Java VM with OS Fully capable J2ME CLDC 1.1 Java VM with OS functionalityfunctionality

VM executes directly out of flash memoryVM executes directly out of flash memory

Device drivers in JavaDevice drivers in Java

Automatic battery managementAutomatic battery management

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SENSOR NETWORKS FEATURESSENSOR NETWORKS FEATURES APPLICATIONS: APPLICATIONS: Military, Environmental, Health, Home, Space Exploration, Military, Environmental, Health, Home, Space Exploration, Chemical Processing, Volcanoes, Mining, Disaster Relief…. Chemical Processing, Volcanoes, Mining, Disaster Relief….

SENSOR TYPES:SENSOR TYPES: Seismic, Low Sampling Rate Magnetic, Thermal, Visual, Infrared, Acoustic, Seismic, Low Sampling Rate Magnetic, Thermal, Visual, Infrared, Acoustic, Radar…Radar…

SENSOR TASKS:SENSOR TASKS: Temperature, Humidity, Vehicular Movement, Lightning Condition, Temperature, Humidity, Vehicular Movement, Lightning Condition, Pressure, Soil Makeup, Noise Levels, Presence or Absence of Certain Types of Pressure, Soil Makeup, Noise Levels, Presence or Absence of Certain Types of Objects, Mechanical Stress Levels on Attached Objects, Current Characteristics Objects, Mechanical Stress Levels on Attached Objects, Current Characteristics (Speed, Direction, Size) of an Object ….(Speed, Direction, Size) of an Object ….

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Sensor TypesSensor Types LightLight

ThermopileThermopile UltravioletUltraviolet IRIR Visible LightVisible Light Color sensorsColor sensors

MagneticMagnetic SoundSound

UltrasoundUltrasound AccelerometerAccelerometer TemperatureTemperature PressurePressure HumidityHumidity Touch sensorsTouch sensors 2.25 in

Microphone

Accelerometer

Light TemperatureSounder

Magnetometer

1.25 in

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Manufacturers of Sensor NodesManufacturers of Sensor Nodes Millenial Net (www.millennial.net)Millenial Net (www.millennial.net)

iBean sensor nodesiBean sensor nodes Ember (www.ember.com)Ember (www.ember.com)

Integrated IEEE 802.15.4 stack and radio on a single chipIntegrated IEEE 802.15.4 stack and radio on a single chip Memsic (http://www.memsic.com)Memsic (http://www.memsic.com)

Mica2 mote, Micaz, Dot mote and Stargate PlatformMica2 mote, Micaz, Dot mote and Stargate Platform Intel ResearchIntel Research

Stargate, iMoteStargate, iMote Dust IncDust Inc

Smart DustSmart Dust Cogent Computer (www.cogcomp.com)Cogent Computer (www.cogcomp.com)

XYZ Node (CSB502) in collaboration with ENALAB@YaleXYZ Node (CSB502) in collaboration with ENALAB@Yale Mote ivMote iv – Telos Mote – Telos Mote

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Manufacturers of Sensor NodesManufacturers of Sensor Nodes In-Q-TelIn-Q-Tel provides distributed data collection solutions with sensor network provides distributed data collection solutions with sensor network

deploymentdeploymenthttp://www.in-q-tel.com/http://www.in-q-tel.com/

ENSCO Inc.ENSCO Inc. invests in wireless sensor networks for meteorological applications invests in wireless sensor networks for meteorological applicationshttp://www.ensco.com/http://www.ensco.com/

EMBEREMBER provides wireless sensor network solutions for industrial automation, provides wireless sensor network solutions for industrial automation, defense, and building automationdefense, and building automationhttp://www.ember.comhttp://www.ember.com

H900 Wireless SensorNet System(TM),H900 Wireless SensorNet System(TM), the first commercially available end-to-end, the first commercially available end-to-end, low-power, bi-directional, wireless mesh networking system for commercial sensors low-power, bi-directional, wireless mesh networking system for commercial sensors and controls is developed by the company called Sensicast Systems. The company and controls is developed by the company called Sensicast Systems. The company targets wide range of commercial applications from energy to homeland securitytargets wide range of commercial applications from energy to homeland securityhttp://www.sensicast.comhttp://www.sensicast.com

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Manufacturers of Sensor NodesManufacturers of Sensor Nodes The The MemsicMemsic (formerly Crossbow) wireless sensor products (formerly Crossbow) wireless sensor products

and its environmental monitoring and other related industrial and its environmental monitoring and other related industrial applications of such as surveillance, bridges, structures, air applications of such as surveillance, bridges, structures, air quality/food quality, industrial automation, process control are quality/food quality, industrial automation, process control are introduced. introduced. http://www.memsic.comhttp://www.memsic.com

Japan's Japan's Omron CorpOmron Corp has two wireless sensor projects in the has two wireless sensor projects in the US that it hopes to commercialize in the near future. Omron's US that it hopes to commercialize in the near future. Omron's Hagoromo Wireless Web Sensor project consists of wireless Hagoromo Wireless Web Sensor project consists of wireless nodes equipped with various sensing abilities for providing nodes equipped with various sensing abilities for providing security for major cargo-shipping ports around the worldsecurity for major cargo-shipping ports around the worldhttp://www.omron.comhttp://www.omron.com

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Manufacturers of Sensor NodesManufacturers of Sensor Nodes Millennial NetMillennial Net builds wireless networks combining sensor interface endpoints and builds wireless networks combining sensor interface endpoints and

routers with gateways for industrial and building automation, security, and telemetry routers with gateways for industrial and building automation, security, and telemetry

http://www.millennialnet.comhttp://www.millennialnet.com

CSEMCSEM provides sensing and actuation solutions provides sensing and actuation solutions http://www.csem.ch/http://www.csem.ch/

Dust Inc.Dust Inc. develops the next-generation hardware and software for wireless sensor develops the next-generation hardware and software for wireless sensor networks networks http://www.dust-inc.comhttp://www.dust-inc.com

Silicon Labs Silicon Labs designs sensors used in medical, automotive, industrial, and military designs sensors used in medical, automotive, industrial, and military applications to cost-effective designs for handheld consumer appliances, barcode applications to cost-effective designs for handheld consumer appliances, barcode readers, and wireless computer input devices readers, and wireless computer input devices http://www.silabs.com http://www.silabs.com

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Manufacturers of Sensor NodesManufacturers of Sensor Nodes MelexisMelexis produces advanced integrated semiconductors, sensor ICs, and produces advanced integrated semiconductors, sensor ICs, and

programmable sensor IC systems. programmable sensor IC systems. http://www.melexis.comhttp://www.melexis.com

ZMDIZMDI designs, manufactures and markets high performance, low power mixed designs, manufactures and markets high performance, low power mixed signal ASIC and ASSP solutions for wireless and sensor integrated circuits.signal ASIC and ASSP solutions for wireless and sensor integrated circuits.http://www.zmdi.comhttp://www.zmdi.com

ChipconChipcon produces low-cost and low-power single-chip 2.4 GHz ISM band produces low-cost and low-power single-chip 2.4 GHz ISM band transceiver design for sensors. transceiver design for sensors. http://www.chipcon.comhttp://www.chipcon.com

ZigBee AllianceZigBee Alliance develops a standard for wireless low-power, low-rate devices. develops a standard for wireless low-power, low-rate devices. http://www.zigbee.comhttp://www.zigbee.com