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
path,isnotactivebecauseofthelackoftheenergy,alongerpathwillservetothepacket.Thelongerthetransporttime,thelessthethroughputandthemoretheenergyconsumption.Theenergyisoneofthemetricinvestigatedin[5].Theenergyconsumptionisinducedbythewell-knownhiddennodeproblemanditssolutionmechanisms.Theyarepresentedin[1].Accordingly,manystudieshavebeendedicatedtoanalyzeitscharacteristicsand/orproposenewroutingmethods(see,e.g.,[5]).Asmentionedin[6],duetothespatialreusepropertyof802.11[2],thenodesnotonlycommunicatebutalsointerferewithothernodes.
III.LESSONSLEARNT
Duringthestudy,weworkedwithdifferentutilitiesthatIdidnothavethechangetoworkwithbefore.TheLINUXasOS,Perlastextinterpreter,ns2asthesimulatorprogramandtheGnuplotasgraphdesigner.IalsotriedtowriteaprojectreportinEnglish,whichisnotobviousatall.WorkingwithLINUXwasnotonlyinterestingbutalsohard.Weworkedwithvariusshellcommands.Inordertoautomatethetasks,wewroteseveralscripts.Theirdevelopmentsarehardbutthenchangingtheparametersfordifferentexecutionsbecomeseasier.Ns2[7]isawell-knownanddevelopedsimulationprogram.Itwasusedtosimulatethedifferentscenarios.Isrequiresnotonlythens2commandsknowledgebutalsonetworkingconceptsknowledge.Forexample,becauseoftheheadersthatareaddedateverylevel,thephysicallayerdatathroughputvaluehastobebiggerthentheMAClayerthroughput.Whena letransferis nished,wehavetoclosetheoutput lesafterenoughtime.Thistimeisnecessarytosaveeveythingonthe les.Happilywedidnothaveinstallationproblems.Theonlyproblemwasthesizeofthetraces les.TheymightbebigenoughtomakeimpossibletoworkwithasinglePC.Aftercertainnumbersoftrace le,theusermighteasilyreachitsharddisklimit.Thatiswhyweerasedthetrace lesbetweeneachexecutionaftergettingthenecessaryinformation.Perlwasusedtoobtainthedesirabledatafromthetrace les.Therearedifferentpossiblewaystogetthesameinformation.Developingtheef cientonetakestimebecausewehavetohaveenoughexperienceonit.Becauseofthelackofthetime,andhavinglotstodo,onlyalittleintroductionsteponitwasdone.Inourcase,itwasusedtogettheenergyleftonthesendernodefromthetrace le.Besidestheuseofdifferenttools,westudiedthemainconceptsbehindadhocnetworks,asexplainedindetailonsectionII,andtheperformanceanalysisofTCPNewrenoandTCPSACKprotocolswithorwithoutDA.Theexperimentisrealizedviathreemetrics.Thoseareenergyconsumption,numberoftheretransmissionandthroughput.
IV.SIMULATIONSETUP
Weusedthens2[7]simulatortoperformourevaluation.Fig.2showsthescenariousedinoursimulations.Eachnodeis200metersapartfromitsclosestneighborsandthewirelessdatarateis2Mbps.Inthesimulator,theeffectivetransmissionrangeis250meterswhiletheinterferencerangeis550metersasrecommendedbytheIEEE802.11standard[2].Inallevaluations,thethroughputbwiscomputedasbw=seq 8