Overview of Sensor Overview of Sensor NetworksNetworks

David CullerDavid Culler

Deborah EstrinDeborah Estrin

Mani SrivastavaMani Srivastava

Wireless Sensor NetworkWireless Sensor Network

►Result of Moore’s LawResult of Moore’s Law►Limited processing speed, storage Limited processing speed, storage

capacity, communication bandwidth, capacity, communication bandwidth, energy sourceenergy source

►Complex interaction between nodesComplex interaction between nodes►Easy deployment and maintenanceEasy deployment and maintenance

Wireless Sensor NetworkWireless Sensor Network

►Applications:Applications: Monitoring spaceMonitoring space Monitoring thingsMonitoring things Monitoring interaction of things with each Monitoring interaction of things with each

other and environmentother and environment

Environmental MonitoringEnvironmental Monitoring

► Monitoring redwood trees: UC BerkeleyMonitoring redwood trees: UC Berkeley

http

://w

ww

.sfg

ate.

com

Motion MonitoringMotion Monitoring

►Monitor motion, vibration, acoustic Monitor motion, vibration, acoustic emissions…etcemissions…etc

►Local processing with continuous Local processing with continuous communicationcommunication

►Signal processing with summary Signal processing with summary communicationcommunication

►Need for real-time interactions Need for real-time interactions between nodesbetween nodes

Embedded Network Embedded Network TechnologyTechnology

►Microprocessor: 1mW, 10MHzMicroprocessor: 1mW, 10MHz►Power source:Power source:

Solar cells: 10mW/cmSolar cells: 10mW/cm22 outdoor outdoor Mechanical: 100Mechanical: 100WW Battery: 1000mAhBattery: 1000mAh

►Memory:Memory: 10KB RAM10KB RAM 100KB ROM100KB ROM

Embedded Network Embedded Network TechnologyTechnology

►Microsensors: convert changes in Microsensors: convert changes in electrical characteristics into digital electrical characteristics into digital signalssignals

►Microelectromechanical systems Microelectromechanical systems (MEMS)(MEMS)

►MicroradiosMicroradios

iMEMS Accelerometer showingStructural beam and surroundingelectronics

Close up of iMEMS accelerationsensor

http

://w

ww

.ana

log.

com

TinyOSTinyOS

►Component-based, event-driven OSComponent-based, event-driven OS Interfaces: Commands and EventsInterfaces: Commands and Events Wiring: Modules and ConfigurationsWiring: Modules and Configurations

►Concurrency modelConcurrency model Executes one program onlyExecutes one program only Tasks and Event handlersTasks and Event handlers

Network Sensor PlatformsNetwork Sensor Platforms

►Mica motesMica motes Simple, Simple,

constrained constrained hardwarehardware

► Intel motesIntel motes Enhanced version Enhanced version

of Micaof Mica ARM processorsARM processors Bluetooth radiosBluetooth radios

http

://w

ww

.xbo

w.c

oht

tp://

ww

w.x

bow

.co

mm

http

://w

ww

.inte

l.co

http

://w

ww

.inte

l.co

mm

Network Sensor Platforms Network Sensor Platforms

►Stargate GatewayStargate Gateway 400MHz, Xscale processor400MHz, Xscale processor PCMCIA, CF card, Ethernet,PCMCIA, CF card, Ethernet,

Serial, JTAG, USB compatibleSerial, JTAG, USB compatible ““Used as points of aggregation, data Used as points of aggregation, data

storage, data fusion, and hosts for storage, data fusion, and hosts for higher-end sensors.”higher-end sensors.”

http

://w

ww

.xbo

w.c

oht

tp://

ww

w.x

bow

.co

mm

Self-organized NetworksSelf-organized Networks

►Organized as mesh networkOrganized as mesh network Routing is adaptive to changingRouting is adaptive to changing

environmentenvironment

►Dissemination and Data collectionDissemination and Data collection Epidemic protocolsEpidemic protocols Directed diffusion – interest pub/sub Directed diffusion – interest pub/sub

modelmodel DTN – reliable hop-by-hop deliveryDTN – reliable hop-by-hop delivery

Physical Layer

Link Layer

Packet Layer

Application

Power and BandwidthPower and Bandwidth

►Possible approachesPossible approaches Turn off radio when not neededTurn off radio when not needed Low powered component wakes up the Low powered component wakes up the

systemsystem Perform local processing and transmit Perform local processing and transmit

summarysummary Compression and schedulingCompression and scheduling

PrivacyPrivacy

►Data travels in unsecured mediumData travels in unsecured medium►Various attacks are possibleVarious attacks are possible►Access control to data is often Access control to data is often

importantimportant

ApplicationsApplications

►PinPtr: Shooter Localization in Urban PinPtr: Shooter Localization in Urban TarrainTarrain Ad-hoc acoustic WSNAd-hoc acoustic WSN Measures muzzle blastMeasures muzzle blast

and shockwaveand shockwave

htt

p:/

/dis

co.in

form

ati

k.u

ni-

htt

p:/

/dis

co.in

form

ati

k.u

ni-

kl.d

ekl

.de

VisionsVisions

►Sensors will become more pervasiveSensors will become more pervasive►Cost of sensors will continue to Cost of sensors will continue to

decreasedecrease►Energy will be harvested from Energy will be harvested from

environmentenvironment►Newer language / signal processing Newer language / signal processing

supportsupport

ReferencesReferences

► http://http://www.tinyos.netwww.tinyos.net► http://http://www.xbow.comwww.xbow.com► http://http://www.intel.com/research/exploratory/motes.htmwww.intel.com/research/exploratory/motes.htm► http://www.sfgate.com/cgi-bin/article.cgi?fhttp://www.sfgate.com/cgi-bin/article.cgi?f

=/c/a/2003/08/18/MN299322.DTL=/c/a/2003/08/18/MN299322.DTL► http://www.analog.com/Analog_Root/sitePage/mainSectionhttp://www.analog.com/Analog_Root/sitePage/mainSection

Content/0,2132,level4%253D%25252D1%2526ContentID%25Content/0,2132,level4%253D%25252D1%2526ContentID%253D7537%2526Language%253DEnglish%2526level1%253D2123D7537%2526Language%253DEnglish%2526level1%253D212%2526level2%253D%25252D1%2526level3%253D%25252D1,%2526level2%253D%25252D1%2526level3%253D%25252D1,00.html00.html

► http://www.cs.rutgers.edu/~rmartin/teaching/fall04/cs552/lehttp://www.cs.rutgers.edu/~rmartin/teaching/fall04/cs552/lectures/route-paradigms.pdfctures/route-paradigms.pdf

► http://www.cse.ogi.edu/~wuchi/Teaching/CSE506/papers/14http://www.cse.ogi.edu/~wuchi/Teaching/CSE506/papers/14/slides.ppt/slides.ppt

► http://disco.informatik.uni-kl.de/courses/moco/Applications/http://disco.informatik.uni-kl.de/courses/moco/Applications/Shooter_Loc_Computer.pdfShooter_Loc_Computer.pdf