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    Please use this identifier to cite or link to this item: https://nccur.lib.nccu.edu.tw/handle/140.119/38541


    Title: 基於群組模式下之大型網路語音會談系統
    A cluster-based transmission scheme for large scale VoIP conferencing
    Authors: 邵育晟
    Contributors: 連耀南
    邵育晟
    Keywords: 語音通話
    點對點
    Date: 2009
    Issue Date: 2010-04-09 14:49:27 (UTC+8)
    Abstract: 利用VoIP進行網路會談(VoIP Conference)在現今的社會已有越來越流行的趨勢，尤其是遠距離語音會議的應用方面，不但能節省費用，還能同時允許多人上線會談，但隨著上線人數的增加，網路的頻寬需求與連線數量相對倍增，通話延遲時間也因頻道擁塞而難以控制，此時會議的品質(QoS)往往大打折扣，網路的負擔也會大幅增加。現行的主要解決方案為選擇網路會議中處理能力較強的使用者設備，將來自個別說話者的聲音經過混音疊加後再轉送給其他使用者，再利用不同架構的multicasting tree廣播語音封包至所有成員，藉此減少網路頻寬與連線數量的負擔，達到增加同時說話人數的目的。但這些作法在使用者所在位置過於分散、遙遠時，仍然會造成許多節點無法達到所需的通話品質。
    本研究針對在大型網路語音會談中，與會人數過多造成通話品質不佳之問題，提出了解決方法，我們假設會議中大部份時間僅有一個說話者，首先為每位使用者加上靜音消除機制，只有發話者的封包直接送給其他所有與會人員，如此不但降低網路負擔，更可以刪除混音的需求，大幅降低傳輸時間，此外並以分群組（Cluster）的方式將位於同一地區的使用者分為同一群組，群組內以Full Mesh機制相連，如此便能建立一複雜度較小的MLDST (Minimum Loss Diameter Spanning Tree) 樹狀結構的multicasting tree用以廣播語音封包至所有成員，可以進一步控制傳輸時間及封包遺失率。我們根據使用者之間彼此的連線速度與實際距離來分群組，從群組中選出連線能力較佳的節點作為群組轉送點(Cluster Head)，透過此轉送點收到聲音後做群組內的發送，並藉由一個multicasting tree將封包在嚴格控制延遲時間及封包遺失率之下，將語音封包廣播至其他所有Cluster Head，以確保VoIP網路會議之品質。
    我們在PlanetLab這種實際網路的實驗平台上進行實驗，評估本方法的效能，實驗結果顯示我們的方法可以在與會人數達到20人時，仍能有效控制延遲時間在350ms左右，若利用Google雲端運算系統的協助，平均延遲時間將可減少50ms至70ms。由於PlanetLab上的電腦性能普遍不佳，我們預期本技術應用於實際網路時，可以增加與會人數。
    Reference: [1] S. Banerjee, B. Bhattacharjee, and C. Kommareddy, "Scalable application layer multicast", in Proc. of ACM SIGCOMM, Pittsburgh, PA, August 2002.
    [2] A. Bharambe, V. Padmanabhan, and S. Seshan, "Supporting Spectators in Online Multiplayer Games", in Proc. of HOTNETSIII, San Diego, November 2004.
    [3] Uyless Black, "VOICE OVER IP", New Jersey: Prentice Hall, 2000.
    [4] M. Castro, P. Druschel, A.-M. Kermarrec, A. Nandi, A. Rowstron, and A. Singh, "SplitStream: High-Bandwdith Multicast in Cooperative Environments", in Proc. of ACM SOSP 2003, New York, October 2003.
    [5] M. Castro, P. Druschel, A.-M. Kermarrec, and A. Rowstron, "SCRIBE: A large-scale and decentralized application-level multicast infrastructure", in Proc. of ACM SIGCOMM, San Diego, CA, August 2001.
    [6] Li-Chen Chi, "Echo Cancellation in Large-Scale VoIP conferencing", 2009.
    [7] Wei-Chung Chiu, "Quality Assurance of Streaming Data Dissemination over P2P Network", 2009.
    [8] Y. H. Chu, S. G. Rao, S. Seshan, and H. Zhang, "Enabling Conferencing Applications on the Internet using an Overlay Multicast Architecture", in Proc. of ACM SIGCOMM, San Diego, CA, August 2001.
    [9] B. Goode, "Voice over Internet Protocol (VoIP)", in Proc. OF THE IEEE, VOL.90, NO.9, Sep. 2002.
    [10] Xiaohui Gu, Z. Wen, Philip S. Yu, and Zon-Yin ShaeZhen, "peerTalk: A Peer-to-Peer Multi-Party Voice-Over-IP System", in Parallel and Distributed Systems, IEEE Transactions, April 2008.
    [11] Xiaohui Gu, Z. Wen, Philip S. Yu, and Zon-Yin ShaeZhen, "Supporting Multi-Party Voice-Over-IP Services with Peer-to-Peer Stream Processing", in Proc. of ACM Multimedia, Singapore, November 2005.
    [12] D. Kostic, A. Rodriguez, J. Albrecht, and A. Vahdat, "Bullet: High Bandwidth Data Dissemination Using an Overlay Mesh", in Proc. of ACM SOSP 2003, New York, October 2003.
    [13] J. Lennox and H. Schulzrinne, "A Protocol for Reliable Decentralized Conferencing", in NOSSDAV`03, Monterey, California, USA, June. 2003.
    [14] B. Li and H. Yin, "Peer-to-Peer Live Video Streaming on the Internet: Issues, Existing Approaches, and Challenges", in IEEE Communications Magazine, Toronto, Ont., Canada, June 2007.
    [15] M. Radenkosvic and C. GreenHalgh, "Multi-party Distributed Audio Service with TCP Fairness", in Proc. of ACM Multimedia, 2002, Juan-les-Pins, France, December 2002.
    [16] Google Talk, http://www.google.com/talk/intl/zh-TW/.
    [17] G.723, http://www.itu.int/rec/T-REC-G.723/e.
    [18] G.729, http://www.itu.int/rec/T-REC-G.729/e.
    [19] Mean Opinion Score, http://en.wikipedia.org/wiki/Mean_opinion_score.
    [20] Skype, http://www.skype.com.
    [21] The E-Model, http://www.itu.int/rec/T-REC-G.107.
    Description: 碩士
    國立政治大學
    資訊科學學系
    96753001
    98
    Source URI: http://thesis.lib.nccu.edu.tw/record/#G0096753001
    Data Type: thesis
    Appears in Collections:[Department of Computer Science ] Theses

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