The Transmission Control Protocol (TCP) represents the most deployed transport protocol used in the Internet so far. This popularity motivates its presence in wireless networks, including ad hoc networks. These networks are very promising since they make i
I.INTRODUCTION
Intoday’sworld,wirelessdevicesbecameanevidentpartofourlife.Thesedevicesmayprovideseamlessconnectivityinenvironmentswherewirednetworksarenotpossibleordesirable.Oneoftheemergingwirelesstechnologiesisadhocnetworks.Thesenetworksareattractivefornotdependingonany xedinfrastructuretocommunicate.Asaresult,researchesonadhocwirelessnetworkshavegainednon-negligiblepopularityinrecentyears.Adhocnetworksconsistofmobilehoststhatcommunicatewitheachotheroverawirelessmediumwithoutcentralcontrol.Theutilisationofthismediumdevelopsthehidden-nodeproblemandexposednodeproblemsthatareinvestigatedinmoredetailin[1].Inanadhocnetwork,thetopologymaychangeduetovariousmediumconstraints,forcingself-reconstructionadaptness.Becauseofthedistancelimit,multihoproutingisusedwherethepacketsareforwardedtowardsthenextnodealongaroutetothereceiver.Energyconsumptionisalsoaconcerninthesenetworksbecausethenodesaresupposedtobebatterypowered.TheIEEEproposedIEEE802.11asastandardMACprotocolforwirelessmultihopnetworks[2].Itde nesthelinkandphysicallayerspeci cations.ItminimizestheknownhiddennodeproblemusingalocalretransmissionstrategywithRTS/CTS(request-to-send/cleartosend)controlframes.Itworksef cientlyforscenarioshavingatmost3hops.Therefore,end-to-endcommunicationprotocolshavetodealwiththeproblemforthebestuseofnetworkbandwidth.ThepopularityoftheTCPintheInternetmotivatesitspresenceonthewirelessnetworks.SinceTCPwasdevelopedforwiredenvironments,ithasdistinctbehaviorinadhocnetworks.Inthesenetworks,TCPwillseeeverydroppedpacketasacongestionsign.Itwillreduceitssendingrate,whichmeanslessthroughput,moreretransmissionsandmorespentenergy.Packeterrorrateofthewirelesschannelsandlinkinterruptionsareotherreasonsforpacketlosses.TheinteractionbetweenTCPandtheIEEE802.11MACprotocolisoneofthemostchallengingtopicsintoday’swirelesscommunicationsystems.TCPNewrenoandTCPSACKaretwoimportant avorsofTCPprotocol.Theirfeaturesarequitedistinctthough.TCPNewrenousesanewfastrecoverymechanismforspeedinguptherecoveryfromlosses.TCPSACKhasareceiverthatgivesmoreinformationaboutthelostpacketstothesender.AsenderofTCPSACKusesthisfeatureforrecoveringquicklyinsituationinwhichmultiplepacketlosseswithinasinglewindowoccur.TCPSACKclaimtobeverygoodtodealwithapacketlossbecauseofitsselectiveacknowledgementstrategy.Nevertheless,addingextrainformationtobesentimplymorespentenergy.BothTCP avorsmayworkwiththedelayedacknowledgement(DA)option,whichmeansthatthereceiveracknowledgesonlyonepacketoutoftwotworeceived.Thisisexpectedtoreduceenergyconsumption.Theaimofthisworkistocharacterize,energyconsumption,numberofretransmissionsandthroughputforTCPNewrenoandTCPSACK avors,withandwithoutDelayedAcknowledgement(DA).Becauseofthetimelimit,wefocusedonthesetwotopical avors.Additionally,wedonotaddressmobilityrelatedissues,sincethegoalhereistoevaluatethebehaviorofTCPovertheIEEE802.11MACprotocol.