Protocols and Applications for Protocols and Applications for Wireless Sensor Networks Wireless Sensor Networks

(204525)(204525)

Ad hoc and Sensor NetworksAd hoc and Sensor Networks

Chaiporn Jaikaeochaiporn.j@ku.ac.th

Department of Computer EngineeringKasetsart University

Materials taken from lecture slides by Karl and Willig

Typical Wireless NetworksTypical Wireless Networks Base stations connected to wired Base stations connected to wired

backbonebackbone Mobile nodes communicate Mobile nodes communicate

wirelessly to base stationswirelessly to base stations

Ad hoc NetworksAd hoc Networks Networks without pre-configured Networks without pre-configured

infrastructureinfrastructure require no hubs, access points, base stationsrequire no hubs, access points, base stations are instantly deployableare instantly deployable can be wired or wirelesscan be wired or wireless

Initially targeted for military and Initially targeted for military and emergency applicationsemergency applications

wired multi-hop wirelesswireless

802.11 Ad hoc Mode802.11 Ad hoc Mode IEEE 802.11 already provides IEEE 802.11 already provides

support for ad hoc modesupport for ad hoc mode Computers can be connected Computers can be connected

without an access pointwithout an access point Only work with single hopOnly work with single hop

Possible Applications for Ad Possible Applications for Ad hoc Networkshoc Networks

ad ho

c

ad ho

c

Factory Floor Factory Floor AutomationAutomation

Disaster recoveryDisaster recovery Car-to-car communicationCar-to-car communication

Characteristics of Ad hoc Characteristics of Ad hoc NetworksNetworks Heterogeneity ― sensors, PDAs, laptopsHeterogeneity ― sensors, PDAs, laptops Limited resources ― CPU, bandwidth, powerLimited resources ― CPU, bandwidth, power Dynamic topology due to mobility and/or failureDynamic topology due to mobility and/or failure

Mobile Ad hoc Networks (MANETs)Mobile Ad hoc Networks (MANETs)

A

BC

Sensor NetworksSensor Networks Participants in the previous examples Participants in the previous examples

were devices close to a human user, were devices close to a human user, interacting with humansinteracting with humans

Alternative concept: Alternative concept:

Instead of focusing interaction on humans, Instead of focusing interaction on humans, focus on interacting with focus on interacting with environmentenvironment Network is Network is embedded embedded in environmentin environment Nodes in the network are equipped with Nodes in the network are equipped with

sensing sensing and and actuationactuation to measure/influence to measure/influence environment environment

Nodes process information and communicateNodes process information and communicate

Remotemonitoring

sensor fieldsensor field

Traditional SensorsTraditional Sensors

NetworkNetworkNetworkNetwork

Localmonitoring

Data loggersData loggers

sensor fieldsensor field

Wireless SensorsWireless Sensors Sensors communicate with data Sensors communicate with data

logger via radio linkslogger via radio links

radio linkRemote

monitoring

NetworkNetworkNetworkNetwork

Wireless Sensor NetworksWireless Sensor Networks Wireless sensors + wireless networkWireless sensors + wireless network Sensor nodes (motes)Sensor nodes (motes) deployed and forming an deployed and forming an

ad hoc networkad hoc network Requires no hubs, access pointsRequires no hubs, access points Instantly deployableInstantly deployable

Targeted applicationsTargeted applications Emergency responsesEmergency responses Remote data acquisitionRemote data acquisition

Sensor network

Sensor node/mote

InternetInternet

Gateway

Remotemonitoring

WSN PlatformsWSN Platforms Most are based on IEEE 802.15.4 Most are based on IEEE 802.15.4

(Wireless Low-Rate Personal Area (Wireless Low-Rate Personal Area Network)Network)

and many others…

WSN Application ExamplesWSN Application Examples AgricultureAgriculture

Humidity/temperatureHumidity/temperaturemonitoringmonitoring

Civil engineeringCivil engineering Structural responseStructural response Disaster managementDisaster management

Environmental sciencesEnvironmental sciences Habitat monitoringHabitat monitoring Conservation biologyConservation biology

WSN in Telemetry WSN in Telemetry ApplicationsApplications

Sensor field

Gateway

wireless sensor node

sensor sensor

GPRSGPRSNetworkNetwork

or Internetor Internet

GPRSGPRSNetworkNetwork

or Internetor Internet

InformationServer

Browser

Landslide MonitorLandslide Monitor Real deployment scenario…Real deployment scenario…

SourcesSources of data: Measure data, report them of data: Measure data, report them “somewhere”“somewhere” Typically equip with different kinds of actual sensorsTypically equip with different kinds of actual sensors

Sinks Sinks of data: Interested in receiving data from WSN of data: Interested in receiving data from WSN May be part of the WSN or external entity, PDA, gateway, … May be part of the WSN or external entity, PDA, gateway, …

Actuators (actors)Actuators (actors): Control some device based on : Control some device based on data, usually also a sinkdata, usually also a sink

Roles of Participants in Roles of Participants in WSN WSN

WSN = WASNWSN = WASN

Classifying Application Classifying Application TypesTypes Interaction patternsInteraction patterns between between

sources and sinks classify sources and sinks classify application typesapplication types Event detectionEvent detection Periodic measurementPeriodic measurement Function approximationFunction approximation Edge detectionEdge detection TrackingTracking

Deployment OptionsDeployment Options Dropped from aircraftDropped from aircraft

Random deploymentRandom deployment Well planned, fixedWell planned, fixed

Regular deploymentRegular deployment MobileMobile sensor nodes sensor nodes

Can move to compensate for Can move to compensate for deployment shortcomingsdeployment shortcomings

Can be passively moved around by Can be passively moved around by some external force (wind, water)some external force (wind, water)

Can actively seek out “interesting” Can actively seek out “interesting” areasareas

Maintenance OptionsMaintenance Options Feasible and/or practical to maintain Feasible and/or practical to maintain

sensor nodes?sensor nodes? Replace batteriesReplace batteries Unattended operationUnattended operation Impossible but not relevantImpossible but not relevant

Energy supplyEnergy supply Limited from point of deploymentLimited from point of deployment Some form of recharging / energy Some form of recharging / energy

scavengingscavenging

Characteristic Characteristic RequirementsRequirements Type of service of WSNType of service of WSN

Not simply moving bits like another networkNot simply moving bits like another network Rather: provide answers (not just numbers)Rather: provide answers (not just numbers) Geographic scoping are natural requirementsGeographic scoping are natural requirements

Quality of serviceQuality of service Fault toleranceFault tolerance Lifetime: node/networkLifetime: node/network ScalabilityScalability Wide range of densitiesWide range of densities ProgrammabilityProgrammability MaintainabilityMaintainability

Required MechanismsRequired Mechanisms Multi-hop wireless communicationMulti-hop wireless communication Energy-efficient operationEnergy-efficient operation

Both for communication and Both for communication and computation, sensing, actuating computation, sensing, actuating

Auto-configurationAuto-configuration Manual configuration just not an optionManual configuration just not an option

Collaboration & in-network processingCollaboration & in-network processing Nodes in the network collaborate towards Nodes in the network collaborate towards

a joint goala joint goal Pre-processing data in network (as Pre-processing data in network (as

opposed to at the edge) can greatly opposed to at the edge) can greatly improve efficiencyimprove efficiency

Required MechanismsRequired Mechanisms Data centric networkingData centric networking

Focusing network design on data, not Focusing network design on data, not on node identifies (id-centric on node identifies (id-centric networking)networking)

To improve efficiencyTo improve efficiency Locality Locality

Do things locally (on node or among Do things locally (on node or among nearby neighbors) as much as possiblenearby neighbors) as much as possible

Exploit tradeoffsExploit tradeoffs E.g., between invested energy and E.g., between invested energy and

accuracy accuracy

MANET vs. WSN - MANET vs. WSN - SimilaritiesSimilarities MANET – MANET – MMobile obile AAd hoc d hoc NetNetworkwork Self-organizationSelf-organization Energy efficiencyEnergy efficiency (Often) Wireless multi-hop(Often) Wireless multi-hop

MANET vs. WSN - MANET vs. WSN - DifferencesDifferences Equipment:Equipment: MANETs more powerful MANETs more powerful Application-specific:Application-specific: WSNs depend WSNs depend

much stronger on application much stronger on application specificsspecifics

Environment interaction:Environment interaction: core of core of WSN, absent in MANETWSN, absent in MANET

Scale:Scale: WSN might be much larger WSN might be much larger (although contestable)(although contestable)

Energy:Energy: WSN tighter requirements, WSN tighter requirements, maintenance issuesmaintenance issues

MANET vs. WSN - MANET vs. WSN - DifferencesDifferences Dependability/QoS:Dependability/QoS: in WSN, in WSN,

individual node may be dispensable individual node may be dispensable (network matters), QoS different (network matters), QoS different because of different applications because of different applications

Addressing:Addressing: Data centric vs. id- Data centric vs. id-centric networkingcentric networking

Enabling Technologies for Enabling Technologies for WSN WSN Cost reduction Cost reduction

For wireless communication, simple For wireless communication, simple microcontroller, system on chip, sensing, microcontroller, system on chip, sensing, batteriesbatteries

MiniaturizationMiniaturization Some applications demand small sizeSome applications demand small size ““Smart dust” as the most extreme visionSmart dust” as the most extreme vision

Energy scavengingEnergy scavenging Recharge batteries from ambient energy Recharge batteries from ambient energy

(light, vibration, …) (light, vibration, …)

ConclusionConclusion MANETs and WSNs are challenging MANETs and WSNs are challenging

and promising system conceptsand promising system concepts Many similarities, many differencesMany similarities, many differences Both require new types of Both require new types of

architectures & protocols compared to architectures & protocols compared to “traditional” wired/wireless networks“traditional” wired/wireless networks

In particular, application-specificness In particular, application-specificness is a new issueis a new issue

DemonstrationDemonstration

Sensor ModulesSensor Modules IWING-MRFIWING-MRF modules from modules from IWING LABIWING LAB

250 kbps 2.4GHz IEEE 802.15.4250 kbps 2.4GHz IEEE 802.15.4 12MHz Atmel ATMega328P microcontroller12MHz Atmel ATMega328P microcontroller Additional light and temperature sensorsAdditional light and temperature sensors

ScenarioScenario

Monitor stationMonitor station

Sensor nodes measuring light intensitySensor nodes measuring light intensity