可靠的多點傳輸協定提供有效率以及可靠的傳輸給有此需求的軟體，而且壅塞控制的機制使得網路傳輸，可以調整傳送速率符合網路上可用的頻寬，並且公平地與目前盛行的網路傳輸方式,TCP, 分享網路頻寬，有許多的服務建構在可靠的多點傳輸的壅塞控制傳輸方式上面。隨著無線網路環境的增加，多點傳輸的服務對於一直增加的可存取網路資源行動裝置日益重要，但是，原本的可靠多點傳輸的壅塞控制會被無線網路中，較高的封包遺失率所影響，造成效能低落，本篇論文提出一個方法，叫做PGMCCW，用來減輕無線網路造成的封包遺失的影響；我們的方法可以分辨出在多點傳輸上無線網路所造成的封包遺失和壅塞所造成的封包遺失，並且在眾多接收端處於不同的網路環境的情況下，選擇適當的回饋資訊，正確地控制整個群組傳送的速率。詳細的演算法和步驟在接下來的章節一一詳述，而提出的方法模擬結果也驗證能有效地改進傳送的效能，在越來越普及的無線網路環境下，達到更佳的傳輸效率。

The reliable multicast protocol provides the efficient delivery and the reliability to the applications. Moreover, congestion control makes the transmissions adapt the sending rate to the available bandwidth and fairly share bandwidth with the popular traffic in the networks, TCP. There are many services built on the reliable multicast congestion control protocols. With the wireless networks increasing, the multicast services are more critical for the more mobile devices accessing the Internet. But the reliable multicast congestion control protocols are affected by the wireless high loss ratio to cause the low performance. This paper presents an approach, called PGMCCW, to alleviate the influence of the wireless losses. It can differentiate the wireless losses and the congestion losses on multicast and elect the proper feedback from the multiple receivers in the different networks. The detailed algorithm is described as the following chapters and the simulations demonstrate that this scheme is effective to improve the performance on the more popular wireless networks.

[1] Varshney, U., “The status and future of 802.11-based WLANs”, Computer, Volume: 36, Issue: 6, June 2003, Pages: 102 – 105.
[2] S. Floyd, V. Jacobson, C.-G. Liu, S. McCanne, and L. Zhang, “A Reliable Multicast Framework for LightWeight Sessions and Application Level Framing”, In Proc. of ACM SIGCOMM ''95, 1995.
[3] J. Nonnenmacher, E. Biersack, and D. Towsley, “Parity-based loss recovery for reliable multicast transmission”, In Proceedings of ACM SIGCOMM ''97, pages 289--300, Sept. 1997.
[4] J. Lin and S. Paul, “RMTP: A Reliable Multicast Transport Protocol”, In INFOCOM, pages 1414--1424, 1996.
[5] V. Jacobson, “Congestion Avoidance and Control”, Proc. ACM SIGCOMM ''88, pages 314--329, August, 1988.
[6] Stewart, R. and Metz, C, “SCTP: new transport protocol for TCP/IP”, Internet Computing, IEEE, Volume: 5, Issue: 6, Pages 64 -- 69, Nov.-Dec. 2001.
[7] B. Whetton, J. Conlan, “A Rate Based Congestion Control Scheme for Reliable Multicast”, Technical White Paper, Oct 1998.
[8] M. Handley and S. Floyd, “Strawman Specification for TCP Friendly (Reliable) Mulicast Congestion Control (TFMCC)”, proposed to the RM mailing list, November 1998.
[9] L. Rizzo, “pgmcc: A TCP-friendly Single-Rate Multicast Congestion Control Scheme”, ACM SIGCOMM 2000.
[10] R. Rejaie, M. Handley, and D. Estrin, “RAP: An end-toend rate-based congestion control mechanism for realtime streams in the Internet”, In Proceedings of INFOCOM, April 1999.
[11] H. Balakrishnan, V. N. Padmanabhan, S. Seshan, and R. H. Katz, “A comparison of mechanisms for improving TCP performance over wireless links”, IEEE/ACM Transactions on Networking (TON), Volume: 5, No. 6, pages 756--769, 1997.
[12] A. Bakre and B.R. Badrinath, “I-TCP: Indirect TCP for Mobile Hosts”, Proc. 15th Internationals Conference on Distributed Computing Systems, pages 136-143, May 1995.
[13] H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, “RTP: A Transport Protocol for Real-Time Applications“, IETF RFC 1889, January 1996.
[14] Jim Gemmell, Todd Montgomery, Tony Speakman, Nidhi Bhaskar, and Jon Crowcroft, “The PGM Reliable Multicast Protocol”, IEEE Network, January/February.
[15] Pragmatic General Multicast specification, URL: http://www.ietf.org/rfc/rfc3208.txt.
[16] Hari Balakrishnan, Srinivasan Seshan, Elan Amir and Randy H. Katz, “Improving TCP/IP Performance over Wireless Network” Proc. 1st ACM Int''l Conf. on Mobile Computing and Networking (Mobicom), Nov. 1995.
[17] Ramakrishnan K. K., Floyd S., "A Proposal to add Explicit Congestion Notification (ECN) to IP," Internet Draft, Work in progress, January 1999.
[18] Shi-Yang Chen, Eric Hsiao-Kuang Wu, and Mei-Zhen Chen, “A New Approach Using Time-Based Model for TCP-Friendly Rate Estimation”, IEEE International Conference on Communications, May. 2003.
[19] Eric Hsiao-kuang Wu, Meizhen Chen, “JTCP, Jitter-based for Wireless Networks”, accepted for IEEE Journal of Selected Area Communications.
[20] Koichi Yano and Steven McCanne, “The Breadcrumb Forwarding Service: A Synthesis of PGM and EXPRESS to Improve and Simplify Global IP Multicast”, ACM Computer Communication Review, Apr. 2000.
[21] H. Holbrook and D. Cheriton, “IP Multicast Channels: EXPRESS Support for Large-scale Single-source Applications”, In Proceeding of Sigcomm ’99, Cambridge, MA, September 1999.
[22] Koichi Yano and Steven McCanne, “A Window-based Congestion Control for Reliable Multicast based on TCP Dynamics”, ACM Multimedia, 2000.
[23] J. Byers, M. Luby, M. Mitzenmacher, and A. Rege, “A Digital Fountain Approach to Reliable Distribution of Bulk Data”, In Proceeding of Sigcomm ’98, Vancouver, Canada, September 1998.
[24] I. Rhee, N. Balaguru, and G. Rouskas, “MTCP: Scalable TCP-like Congestion Control for Reliable Multicast”, In Proceedings of IEEE INFOCOM, pages 1265--73, March 1999.
[25] NS-2 network simulator LBL URL: http://www.mash.cs.berkley.edu/ns.