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1、WirelessCommunicationNetworksoverTCP,ATMandLocationUpdateandPagingPoliciesENEE609AIndependentStudyTermReportEsinHaritaoglu1WirelessCommunicationNetworksoverTCPInrecentyears,avarietyofmobilecomputersequippedwithwirelesscommunicationdeviceshavebecomepopular.Thesecomputersuseapplicationsandprotocols,or
2、iginallydevelopedforwireddesktophoststocommunicateoverwirelesschannels.TCPisthemostwidelyusedtransportprotocolonthesecomputers,becauseitisspeci callydevelopedbyArpanetforreliabledatatrans-missionoverwirednetworks.AlongwithTCP,astandardlinklayerprotocolIP(InternetProtocol)isalsodevelopedbyArpanetandT
3、CP/IPisusuallyusedtogetherasastandardInternetProtocolSuite.AlthoughTCP/IPiscommonlyused,bothTCPandIPareindependentdi erenttypeofprotocolsandtheycanbeadaptedforusewithotherprotocols(e.gUDP/IP,TCP/MAC).SinceTCPisdevelopedspeci callyforwirednetworkswherethecongestionistheprimarycauseofpacketloss,itperf
4、ormswellandprovidesreliabledatadeliveryinthesenetworksbymeansofend-to-end
owcontrol,congestionanderrorcontrolmechanisms.However,theend-to-endperformanceofaTCPconnectioncansu ersigni cantdegradationinthepresenceofawirelesslinkbecausenetworkswithwirelesslinkandmobilehostsincursigni cantlossesduetohand
5、o sandcharacteristicsofwirelesstransmissionenvironment.ThiswirelessenvironmentviolatesmanyoftheassumptionsmadebyTCP,causingdegradedend-to-endperformance.TounderstandhowTCPperformancedegradesseverelyoverwirelesslinks,weshould rstlookattheend-to-end
ow,congestionanderrorcontrolmechanismsofTCP.1.1Relia
6、bleTransmissionControlProtocol(TCP)Atthelowestlevel,computercommunicationnetworksprovideunreliablepacketdelivery.Packetscanbelostwhentransmissionerrorsinterferewithdata,whennetworkhardwarefailsorwhennetworkbecometooheavilyloadedtoaccommodatetheloadpresented.Networksthatroutepacketsdynamicallycandeli
7、verthemoutoforder,deliverthemafterasubstantialdelayordeliverduplicates.Atthehighestlevel,applicationprogramsoftenneedtosendalargevolumesofdatafromonecomputertoanother.Usingunreliableconnectionlessdeli
