overWiMedia UWB Networks
Jihyun Lee, Kyungshik Lim, Kwangil Lee, Junhee Park, Kyeong-Deok Moon · 2008
behavior oftheconventional TCP. Abstract-- TheWiMediaUWB technology isaviable solution toprovide highthroughput formultimedia streams infuture wireless multimedia homenetworks. Thequality ofexperience forhomeusers, however, couldnotbesatisfactory duetothe severe degradation oftheTCPthroughput caused bylateTCP ACK-clocking. Tosolve theproblem, wepropose across-layer FastTCPACK-Clocking (FTAC)scheme, whereanormalMAC ACK conveysa TCP ACK inbothcontention-based and reservation-based MAC protocols. WithFTAC,itisshownby simulation thattheutilization ofUWB linkbyTCP isgreatly enhanced andtheTCPthroughput approaches tothatofUDP, whichcouldbetheupperboundoftheutilization ofUWB links byhigher layers. I.INTRODUCTION Thereisagrowing demandforhigh-quality multimedia streaming services suchasHigh-Definition video streams in future wireless homenetworking environments(1). Oneofthe mostpromising technologies to support highwireless throughput above100MbpsisUltra-Wideband (UWB).The WiMediaAlliance(2) hasspecified aphysical-layer standard based onmultiband-OFDM withadata rate ofupto480Mbps anda fully distributed MediumAccessControl (MAC) protocol forUWB communication. Consumer electronic (CE) devices mightusecontention-based Prioritized Channel Access(PCA)forasynchronous traffic and/or reservation- based Distributed Reservation Protocol (DRP)forisochronous traffic. AsshowninSection III, inthestandard WiMedia UWB MAC withanaverage BERbetter than106oenvironment, the TCPthroughput isapproximately half oftheUDPthroughput. Thisinherently stemsfromtheTCPACK-clocking problem that TCPACK mustcompete withother traffics onthebasis ofcontention and/or reservation. Eventhough theWiMedia UWB links provide over100Mbps bandwidth forwireless homenetworking, theQoSexperienced byCEusers could not besatisfactory duetothebandwidth insufficiency caused by slowTCP ACK-clocking problem. In two or more neighboring UWB networks interconnected byahigh-speed homenetwork suchasHomePlug Audio/Video (HPAV), the situation could begetting worse. Inthis paper, wepropose a cross-layer design forFastTCPACK-Clocking (FTAC). The proposed scheme extends anormal MAC acknowledgement to convey aTCPACK sothat aUWB channel canbeusedby extended MAC ACKs andaccelerate theACK-clocking