Transpo
Download
1 / 35

Transpo rt Protocols in - PowerPoint PPT Presentation


  • 85 Views
  • Uploaded on

Transpo rt Protocols in. Wireless Sensor Networks. Kevin Mendes Lakehead University. Topics to be Covered. Trans p ort Protocol O bjectives Draw b acks of TCP in W SNs Design Guid e li n es ( Performa n ce Metrics ) Cong e stion Control & its Causes Loss Recove r y.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Transpo rt Protocols in' - senona


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

TransportProtocolsin

WirelessSensorNetworks

Kevin Mendes

Lakehead University


Topics to be covered
Topics to be Covered

  • TransportProtocol Objectives

  • Drawbacksof TCPin WSNs

  • DesignGuidelines (PerformanceMetrics)

  • CongestionControl & its Causes

  • LossRecovery


Trans p ort protocol o bjectives
TransportProtocol Objectives

  • Transportprotocolsare usedto:

    • Mitigatecongestion,

    • Reducepacketloss,

    • Providefairnessin bandwidthallocation,

    • Guaranteeend-to-endreliability.

  • Thetraditionaltransport protocols (i.e.,UDPandTCP) cannot be directlyimplementedfor WSNs

    • UDPdoesnotprovidedeliveryreliabilitythatisoftenneeded formanysensorapplications,

    • Nordoesitofferflow andcongestioncontrolthatcanlead to packetlossandunnecessaryenergyconsumption.


Draw b acks of tcp in w sns
Drawbacksof TCPin WSNs

  • Overheadassociatedwith TCP connection

  • establishment

  • Flow andcongestioncontrol mechanismsinTCP

    • Resultin unfairbandwidthallocationanddatacollections.

    • TCPassumesthatpacketlossisduetocongestion

    • TCPhasadegradedthroughputin wirelesssystems

  • TCPrelieson end-to-endretransmission

    • Consumesmoreenergyandbandwidththanhop-by-hop

  • retransmission.

  • TCPguaranteessuccessfultransmissionof packets

    • Isnotalwaysnecessaryforevent-drivenapplicationsin

  • sensornetworks.


Design guid e li n es
DesignGuidelines

  • In WSNsseveralnewfactors,canresultin congestion:

    • Convergentnature ofupstreamtraffic

    • Limited wirelessbandwidth

  • TworeasonsofpacketlossinWSNs:

    • Packet loss dueto congestioninintermediate nodes

    • Packet loss dueto bit-error rate(number of bit errors divided by the total number of transferred bits during a studied time interval)inwirelesschannel

  • TwomajorproblemsthatWSNtransport protocolsneedtocopewith:

    • Congestion

    • Packet loss.


Performa n ce metrics
PerformanceMetrics

  • TransportprotocolsforWSNsshouldprovide:

    • End-to-endreliability

    • End-to-endQoS

  • Performancemetrics:

    • Energy efficiency,

    • Reliability,

    • QoS

      • Packet-lossratio,

      • Packet-delivery

      • Latency

    • Fairness.


PerformanceMetrics: EnergyEfficiency

  • Sensornodeshave limitedenergy.

  • Transportprotocolsshouldmaintainhighenergy efficiency

    • Tomaximizesystemlifetime.

  • Forloss-sensitiveapplications,

    • Packetlossleadstoretransmission

    • Inevitableconsumptionofadditional batterypower

  • Therefore,severalfactorsneedtobecarefully

  • considered,

    • Numberofpacketretransmissions,

    • Distance(e.g.,hop)foreachretransmission,

    • Overheadassociatedwithcontrolmessages.


PerformanceMetrics: Reliability

  • ReliabilityinWSNscanbeclassifiedintothe

  • following categories:

    • Packet reliability:

      • Applicationsareloss-sensitiveandrequiresuccessful transmissionofall packetsorata certainsuccessratio.

    • Event reliability:

      • Applicationsrequireonly successfuleventdetection,but

  • notsuccessfultransmissionofallpackets.

    • Destination-relatedreliability:

      • Messagesmightneedtobe deliveredtosensornodes:

        • Thatarein aspecificsubarea

        • Thatareequippedwithaparticularsensortype.


PerformanceMetrics: QoSMetrics

  • QoSmetricsinclude:

    • Bandwidth,

    • Latencyor delay,

    • Packet-loss ratio.

  • Dependingontheapplication,thesemetricsor theirvariantscouldbeused forWSNs.

    • TargettrackingApplication:

      • Generatehigh-speeddatastreams

      • Requirehigherbandwidth

    • Fora delay-sensitiveapplication:

      • Mayalsorequiretimelydeliverydata.


PerformanceMetrics: Fairness

  • What if Sensornodesarescatteredinageographical

  • Area?

  • Many-to-oneconvergentnatureofupstream

  • traffic:

    • Itis difficult forsensornodesthatare farawayfrom thesinkto transmitdata.

  • Transportprotocolsneedtoallocate

  • bandwidthfairlyamongallsensornodes

    • Sink can obtaina fairamount of data fromall the sensor nodes.


Cong e stion control
CongestionControl

Closed-loopcontrol

feedback

Feedbackshouldbefrequent,butnottoomuchotherwisetherewillbeoscillations Cannotcontrolthebehaviorwith atimegranularitylessthanthefeedbackperiod


Ef f ect of cong e stion
EffectofCongestion

  • Packetloss

  • Retransmission

  • Reducedthroughput

  • Congestioncollapsedue to

    • Unnecessarilyretransmittedpackets

    • Undeliveredorunusablepackets


Con g estion control in the int e rnet
CongestionControlintheInternet

improving the efficiency of TCP/IP networks by reducing the number of packets that need to be sent over the network.

ActiveQueue Management(AQM)

TCPCongestionControl


Causes for congestion in w s ns
CausesFor Congestion in WSNs

  • Duetothepacket-arrivalrateexceeding

  • thepacket-servicerate.

    • Thisismorelikelytooccuratsensornodes

  • closeto thesink

  • Link-levelperformanceaspectssuchas:

    • Contention,

    • Interference,

    • Bit-errorrate.

    • Thistypeof congestionoccursonthelink.


Types of congestion in wsns
Typesof Congestionin WSNs

  • NodeLevel Congestion:

    • It isduetothepacket-arrival rateexceedingthepacket- servicerate.

    • Thisis morelikelytooccur at sensornodesclosetothe sink.

  • LinkLevel Congestion:

  • It aspects suchas contention,interference,and bit-errorrate.


Ef f ects of cong e stion in w sns
EffectsofCongestion in WSNs

  • Energy:

    • Wastethelimitednodeenergy

  • ApplicationQoS:

    • Degrade reliabilityandapplicationQoS

  • Buffer overflow

    • Larger queuingdelays

    • Higherpacket loss.

  • Degrade linkutilization.

  • ItresultsintransmissioncollisionsifCSMA,is

  • used

    • increases packet-servicetime

    • wastes energy.


Cong e stion control approac h es
CongestionControlApproaches

  • Therearetwogeneralapproachesto

  • controlcongestion:

    • Networkresourcemanagement:

      • triesto increasenetwork resource to mitigate congestion

    • Trafficcontrol:

      • impliesto control congestionthroughadjusting trafficrate atsource nodesor intermediates nodes


Traffic control metho d s
TrafficControlMethods

  • End-to-end:

    • Can imposeexact rate adjustment at each source node

    • Simplify the designat intermediatenodes

    • Itresults inslowresponseandrelieshighlyonthe

  • round-triptime (RTT).

  • Hop-by-hop:

    • Ithas fasterresponse.

    • Difficultto adjust thepacket forwardingrate at intermediate nodes

      • BecausepacketforwardingrateisdependentonMAC

  • protocolandcouldbe variable.


Cong e stion control parts
CongestionControlParts

  • Congestiondetection

    • Monitor buffer/queue size

    • Monitor channelbusy time, estimatechannel’sload

    • Monitor theinter-packet arrivaltime (data,ctrl)

  • Congestionnotification

    • Explicitcongestionnotificationinpacketheader,then broadcast (but then energy-consuming!)

  • RateAdjustment

    • Dynamic reportingrate dependingon congestionlevel

    • In-networkdatareductiontechniques(agressive

  • aggregation)oncongestion


Cong e stion detection
CongestionDetection

  • In TCP:

    • Congestionis observedat theendnodesbasedon atimeoutor redundantAcknowledgments.

  • In WSNs:

    • Proactivemethods are preferred.

  • Congestion indicators:

    • Queuelength

    • Packet service time

    • Theratioof packet servicetimeover packet

  • interarrivaltime


Cong e stion notification
CongestionNotification

  • Propagationofcongestioninformationfromthe

  • congested node

    • Totheupstreamsensornodes

    • Tothesourcenodesthatcontributetocongestion

  • Congestioninformation

    • CongestionNotification(CN)bit,

    • Ormoreinformationsuchasallowable datarate,orthe congestiondegree.

  • Disseminatingcongestioninformation:

    • Explicit

      • Usesspecialcontrol messagesto notifytheinvolvedsensor nodes of congestion

    • Implicit

      • Piggybackscongestioninformationin normaldata packets.


Rate adjustment
RateAdjustment

  • Uponreceivingacongestion indication,a

  • sensornodecanadjustitstransmissionrate.

  • If a singleCNbitisused:

    • AdditiveIncreaseMultiplicativeDecrease(AIMD)

  • If additionalcongestion informationis available:

    • Accuraterate adjustmentcanbe implemented


Loss recove r y
LossRecovery

  • Reasonsofpacket loss in wirelessenvironments:

    • Congestion

    • Biterror

    • nodefailure,

    • wrongoroutdatedroutinginformation,

    • Energydepletion.

  • How to overcomethisproblem:

    • Increasethesourcesendingrate

      • Workswellforguaranteeingevent reliability

      • Isnotenergyefficient

    • Introduceretransmission-basedlossrecovery.

      • Ismoreactiveandenergyefficient

      • Can be implementedat both thelinkand transportlayers.

        • Link-layerloss recoveryis hop-by-hop,whilethetransportlayer recoveryis usuallydoneend-to-end.


Loss detection and notification
LossDetection andNotification

  • Acommonmechanismis toincludea sequencenumberineachpacket header.

  • Thecontinuityofsequencenumbers can beusedtodetectpacketloss.

  • Lossdetectionandnotificationcanbe:

    • End-to-end

    • Hop-by-hop.


En d to end ap p roaches
End-to-EndApproaches

  • End-points(destinationorsource)are

  • responsibleforlossdetectionandnotification.

  • Drawbacks

    • Isnotenergy efficient.

      • Thecontrolmessageswould utilize areturnpath consistingofseveralhops

    • Control messagestravelthroughmultiplehops

      • Couldbe lostwitha highprobabilityduetoeitherlinkerror orcongestion.

    • Leads toend-to-endretransmissionsfor loss

  • recovery.


Ho p b y hop loss detection and notif i cation
Hop-by-hopLossDetectionand Notification

  • Intermediatenodesdetectandnotifypacket

  • loss.

  • Apairofneighboringnodesareresponsible

  • for lossdetection.

  • Is moreenergyefficient.

  • Twocategories:

    • Receiver-based

      • Receiverinferspacketlosswhenitobservesout-of- sequencepacketarrivals.

    • Senderbased

      • Senderdetectspacketlossoneitheratimer-basedor overhearingmechanism.


Metho d s to notify the sender
MethodstoNotify theSender

  • Specialcontrolmessages:

    • ACK(Acknowledgment)

    • NACK(NegativeACK)

  • PiggybackingACKinthepacket header

    • IACK(ImplicitACK) usingoverhearing

      • Avoids control messageoverhead

      • Moreenergyefficient.

      • Sensor nodesmusthavethecapabilitytooverhearthephysical

  • channel.

    • Isnotfeasiblewhen:

      • Transmissionis corrupt

      • Channelisnotbidirectional

      • Sensornodesaccess thephysicalchannelusingTimeDivision MultipleAccess(TDMA)-basedprotocols


Retransmission-BasedLoss Recovery

  • End-to-end

    • The source performsretransmission.

  • Hop-byhop.

    • Anintermediatenodethat interceptsloss notification searchesitslocalbuffer.

    • Ifitfinds a copy of thelostpacket, it retransmits the packet.

    • Otherwiseitrelayslossinformation upstreamto

  • otherintermediatenodes.


Comp a riso n s
Comparisons

  • End-to-end retransmission:

    • Thecachepointis thesourcenode.

    • Hasalongerretransmissiondistance

    • Allowsforapplication-dependentvariablereliabilitylevels

  • Hop-by-hopretransmission:

    • Thecachepointcouldbethepredecessornodeoftheloss point.

    • Ismoreenergy-efficient

    • Requiresintermediatenodestocachepackets.

    • Ispreferredif100percentpacketreliabilityis required

    • Cannotassuremessagedeliveryin thepresenceofnode

  • failure


Issues relat e d to hop b y hop retransmission
IssuesRelated toHop-by-hop Retransmission

  • Immediateretransmission

    • Retransmissioncanbe triggeredimmediatelyuponthe detectionofa packetloss.

    • Resultsin shorterdelay

    • Ifpacketlossiscausedbycongestionitcouldaggravatethe

  • congestionsituationandcausemorepacketlosses.

  • Distributed TCP Cache(DTC)

    • Giventhelimited memoryin sensornodes,packetsmayonly

  • needtobecachedatselectednodes.

    • Howtodistributecachedpacketsamongasetofnodes?

    • Itbalancethebufferconstraintsandretransmissionefficiency byusingprobability-basedselectionforcachepoints.


Design guidel i nes
DesignGuidelines

  • Severalfactorsmustbetaken into consideration:

    • Topology

    • Diversityofapplications

    • Trafficcharacteristics

    • Resourceconstraints

  • Transportprotocolscomponents

    • Congestioncontrol

    • Lossrecovery

  • Twoapproaches

    • Designseparateprotocolsoralgorithms,respectively,for congestioncontrolandlossrecovery.

    • Providescongestionandlosscontrolin an integratedway

    • Thejointuseofthesetwoprotocolsmayprovidethefull

  • functionalityrequiredbythetransportprotocolsforWSNs.


The existing transport protocols for wsns
TheExisting TransportProtocolsfor WSNS

  • ProtocolsforCongestionControl

    • CongestionDetectionandAvoidance(CODA)

    • Control andFairness (CCF)

    • PumpSlowlyFetch Quickly(PSFQ)

    • Priority-basedCongestionControlProtocol(PCCP)

    • Siphon

    • Adaptive Rate Control(ARC)

    • Trickle

  • ProtocolsforReliability

    • ReliableMulti-Segment Transport(RMST)

    • ReliableBurstyConvergecast(RBC)

    • Event-to-Sink ReliableTransport (ESRT)

    • GARUDA

  • ProtocolsforCongestionControlandReliability

    • Sensor TransmissionControlProtocol(STCP)


W s n con g estion con t rol prot o cols
WSNCongestionControlProtocols

  • CCF :

  • Packetservicetime

  • Implicit

  • Exact hop-by-hoprate adjustment

  • STCP:

    • Queuelength,

    • Implicitcongestionnotification,

    • AIMD-like end-to-endrate adjustment

  • Fusion:

    • Queuelength,

    • Implicitcongestionnotification,

    • Stop-and-starthop-by-hoprate

  • adjustment

  • CODA:

    • Queuelengthand channel status,

    • Explicitcongestionnotification,

    • AIMD-likeend-to-endrate

  • adjustment

  • PCCP:

  • Packetinterarrivaltime and packetservicetime,

  • Implicitcongestionnotification,

  • Exact hop-by-hoprate

  • adjustment

  • ARC:

  • Theevent if thepackets are successfully forwardedor not,

  • Implicitcongestionnotification,

  • AIMD-like hop-by-hoprate adjustment


References
References

A Survey of Transport Protocols for

Wireless Sensor Networks: Chong gang Wang and KazemSohraby, University of Arkansas

Link:http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01637930


Thank you
Thank You

  • Any Questions???


ad