ATM網路上多媒體通訊之遲滯性服務品質控制

Abstract

隨著高速網路技術的進步,使得多元化媒體如聲音,視訊,以及資料的多媒 體通訊系統得以發展.為了要傳輸這些需要不同服務品質的各種訊務源,由 下層網路和終端系統所構成的多媒體通訊系統,必需根據不同的訊務源等 級,提供不同的服務品質保證.在此論文中,我們提出ATM網路上多媒體通訊 之遲滯性服務品質控制機制.首先,基於 Earliest-Due-Date (EDD)乃廣域 ATM網路上用於提供服務品質保證最具成效的定序法則之一,我們提出一可 行的系統架構並進行深入的效能分析,以促使EDD定序法則得以實際應用在 ATM網路上.其次,儘管下層網路可為多媒體通訊提供 end-to-end 遲滯保 證,支援各種多媒體應用的終端系統仍需致力於解決網路造成的遲滯振盪. 特別是在高速網路中,支援多媒體資料的多媒體通訊,通常需要影像能夠平 順播放以維持影像播放的連續性.為了要滿足這種需求,我們在接收端終端 系統提出一影像平順播放機制,稱之為影像平順器(Video Smoother),用於 即時影像播放的應用以維持一定的播放品質. The advance of high speed network technology has enabled the development of the multimedia communication systems supporting all conceivable media including voice, video, and data. For transporting such a diverse mix of traffic sources requiring different Quality Of Services (QOSs), multimedia communication systems consisting of the underlying networks and the end systems are demanded to provide QOS guarantees for different classes of traffic sources. This thesis aims at providing delay- basedQOS control mechanisms for multimedia communications through ATM networks. First, regarding the Earliest-Due-Date (EDD) as one of the most promising scheduling disciplines providing QOS guarantees in wide area ATM Networks, we propose a feasible implementation architecture and in-depth performance analysis for the realization ofthe EDD scheduling discipline. Second, while the underlying network provides the end-to-end delay guarantees for multimedia communications, resolutions of networkdelay jitters in end systems supporting diverse multimedia applications are highly essential. In particular, multimedia communications supporting multimedia data in high speed networks often require the smoothing of video playout to prevent potential playout discontinuity while still achieving satisfactory playout quality. To satisfy this need, in this thesis, we propose a novel video playout smoothing mechanism, called the Video Smoother, in receiving end systems to guarantee acceptable playout quality for real-time video applications.