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研究生:鄭明宗
研究生(外文):Ming-Tsung Cheng
論文名稱:利用序號補償達成DCCP部分可靠性延伸
論文名稱(外文):DCCP Partial Reliability Extension with Sequence Number Compensation
指導教授:賴源正賴源正引用關係
指導教授(外文):Yuan-Cheng Lai
學位類別:碩士
校院名稱:國立臺灣科技大學
系所名稱:資訊管理系
學門:電算機學門
學類:電算機一般學類
論文種類:學術論文
論文出版年:2008
畢業學年度:96
語文別:英文
論文頁數:37
中文關鍵詞:封包擁塞控制協定(DCCP)多媒體應用重傳部分可靠性
外文關鍵詞:Datagram Congestion Control Protocol (DCCP)multimedia applicationretransmissionpartial reliability
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封包擁塞控制協定(Datagram Congestion Control Protocol, DCCP)具備擁塞控制機制及不可靠傳輸的特性,非常適合具及時性的多媒體應用。然而對某些應用而言,某些關鍵性封包的遺失恐會造成服務品質的大幅降低,因此若是能將遺失且具關鍵性的封包在其有效的時間內加以重傳,如此服務品質必能顯著提升。本論文在DCCP上提出由傳送端決定封包是否要重傳的partially reliable DCCP (PR-DCCP),由於無可靠機制的DCCP所使用的序號會持繼增加,即使重傳時也無法使用原始的序號,因此PR-DCCP使用封包序號補償來解決此問題,其概念為重傳之封包會附加一個差距值,如此receiver可利用序號及差距值來得到原始需重傳封包的序號。模擬結果顯示PR-DCCP在Decodable Frame Ratio(DFR) 與Useless Data Received Ratio(UDRR)上都優於其他傳輸層協定DCCP、SCTP、TCP、UDP。針對各種不同的影片,PR-DCCP的DFR可比DCCP增加1.9%~14.8%,而UDRR則可降低約86.8%~90.5%。
Datagram Congestion Control Protocol (DCCP), possessing congestion control and unreliable transmission, specially suits real-time multimedia applications. Nevertheless, losses of key packets will cause a substantial decline on quality of services (QoS) in some applications. This paper proposes a DCCP partial reliability extension (PR-DCCP) that can retransmit lost packets as needed. Since DCCP uses an incremental sequence number, the retransmitted packets cannot utilize their original sequence number. To solve this problem, PR-DCCP adopts sequence number compensation, which appends an offset to the retransmitted packet; thus the receiver can use the sequence number of this retransmitted packet and the attached offset so as to re-obtain the original sequence number. The simulation uses two performance metrics: Decodable Frame Ratio (DFR) representing QoS, and Useless Data Received Ratio (UDRR) representing the bandwidth waste. These are used to evaluate different transport protocols, namely, PR-DCCP, DCCP, SCTP, TCP, and UDP. Simulation results show that PR-DCCP has the better DFR and UDRR than other transport protocols in almost all cases. For various movies, a DFR of PR-DCCP is 1.2% - 12.4% higher than that of DCCP; while UDRR is lower by 73.2% - 85.1%. Furthermore, two reliability policies to determine which packets require reliability are investigated. Finally, the comparisons between PR-DCCP and PR-SCTP are examined.
摘要 I
Abstract II
誌謝 III
Table of Contents IV
List of Figures VI
List of Tables VII
Chapter 1. Introduction 1
Chapter 2. Background 4
2.1. DCCP Overview 4
2.1.1. DCCP Sequence Number 4
2.1.2. DCCP Option 5
2.1.3. Ack Vector Option 5
2.1.4. DCCP Operation 7
2.2. Partial Reliability 8
Chapter 3. Protocol Description of PR-DCCP 10
3.1. Data Structures of PR-DCCP 11
3.1.1. Sending Buffer 11
3.1.2. Retransmitted Packet Vector 12
3.1.3. Receiving Buffer 14
3.2. Sender’s Behavior 15
3.3. Receiver’s Behavior 20
3.4. An Example for PR-DCCP 21

Chapter 4. Simulation and Evaluation 24
4.1. Simulation Environment 24
4.2. Performance of Different Protocols 26
4.3. Different Videos 29
4.4. Reliability Policy 30
4.4.1. Policy by the Packet Lifetime 31
4.4.2. Policy by the Packet Significance 32
Chapter 5. Comparison with PR-SCTP 33
5.1. Differences between PR-DCCP and PR-SCTP 33
5.2. Performance Comparison between PR-DCCP and PR-SCTP 35
Chapter 6. Conclusion 36
Reference 37
[1]E. Kohler, M. Handley, S. Floyd, and J. Padhye, “Datagram Congestion Control Protocol (DCCP),” IETF RFC 4340, March 2006.
[2]E. Kohler, M. Handley, and S. Floyd, “Designing DCCP: Congestion Control Without Reliability,” SIGCOMM’06, September 2006.
[3]H. Wang, Y. Jin, W. Wang, J. Ma, and D. Zhang, “The Performance Comparison of PRSCTP, TCP and UDP for MPEG-4 Multimedia Traffic in Mobile Network,” ICCT 2003, April 2003.
[4]R. Stewart et al., “Stream Control Transmission Protocol (SCTP),” IETF RFC 2960, October 2000.
[5]R. Stewart, M. Ramalho, Q. Xie, M. Tuexen, and P. Conrad, “Stream Control Transmission Protocol (SCTP) Partial Reliability Extension (PR-SCTP),” IETF RFC 3758, May 2004.
[6]The Network Simulator - ns-2. http://www.isi.edu/nsnam/ns
[7]http://www.tkn.tu-berlin.de/research/trace/ltvt.html
[8]Z. Lifen, S. Yanlei, and L. Ju, “Performance Study of Transmitting MPEG4 over SCTP,” IEEE International Conference on Neural Networks & Signal Processing, December 2003.
[9]A. Ziviani, B. E. Wolfinger, J. F. Rezende, O. C. M. B. Duarte, and S. Fdida, “Joint Adoption of Qos Schemes for MPEG Streams,” Multimedia Tools and Applications, vol. 26, no. 1, pp. 59-80, May 2005.
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