本論文提出一套在多點跳躍隨意式網路上，針對即時影音串流的智慧型封包提早丟棄機制(I-EPD)，在多點跳躍的隨意式網路上傳送即時影音串流會遭遇到很多問題，因為各個中間節點的暫存佇列空間較小、無線網路的頻寬有限，且各個中間節點皆有可能因為移動或是裝置關機而造成傳送路徑的斷線，而當網路發生壅塞或是傳送路徑斷線時，即會造成中間節點的封包累積，當封包累積在中間節點時，因為即時影音串流的封包具有時效性，所以暫存在中間節點的封包可能會發生超過Jitter容忍度而產生過期的現象，暫存佇列中的過期封包就算可以傳送到接收端也將是無用的封包，而我們提出的I-EPD能夠在中間節點利用RTP標頭的Timestamp標籤以及利用RTCP量測到的RTT來判斷封包的即時性，並將暫存在代傳佇列中的過期封包丟棄，以更有效地利用中間節點的暫存佇列空間與無線網路頻寬，並提升即時影音串流的品質。
為了驗證我們提出機制的優越性，我們在Linux平台上實作I-EPD的機制，測試傳送不同Bit Rate的影片與不同路徑修復時間下，使用與未使用I-EPD的影響，並透過PSNR來驗證應用層影像畫面的改善情形，也可證明I-EPD確實能夠使中間節點的暫存佇列空間得到更有效的利用，並可避免因傳送過期封包而造成無線頻寬的浪費。

This thesis presents an intelligent early packet discard (I-EPD) for real-time video streaming over a multi-hop ad hoc network. In a multi-hop ad hoc network, the quality of transferring real-time video streams could be seriously degraded, since every intermediate node (IN) functionally like forwarding device does not possess large buffer and sufficient bandwidth. Even worse, a selected forwarding node could leave or power off unexpectedly which breaks the route to destination. Thus, a video packet temporarily buffered in intermediate nodes may exceed its time constraint when either a congested or failed link occurs; a stale video packet is useless even if it can reach destination after network traffic becomes smooth or failed route is reconfigured. In the proposed I-EPD, an IN can intelligently determine whether a buffered video packet should be discarded based on an estimated time constraint which is calculated from the RTP timestamps and the round trip time (RTT) measured by RTCP.
For the purpose of validation, we implement the I-EPD scheme on a Linux-based embedded system. We compare the quality of video streams under different bit rates and different route repair time. In addition, we use PSNR to validate the quality of pictures from the aspect of application layer. The experimental results demonstrate that with I-EPD buffer utilization on IN can be more effectively used and unnecessary bandwidth wastage can be avoided.

第一章 導論 1
1.1研究動機 1
1.2研究方向與方法 1
1.3章節介紹 3
第二章 Ad Hoc網路中的串流品質 4
2.1 MPEG-4與RTP 4
2.1.1 MPEG-4簡介 4
2.1.2 使用RTP傳送MPEG-4影音串流 5
2.2 改進影音串流品質的相關研究 6
2.2.1 使用RTCP提升串流品質 6
2.2.2 設定不同優先權 7
2.2.3 路徑管理機制 7
2.2.4 改進中間節點 8
2.2.4.1 允入控制機制 8
2.2.4.2 封包提早丟棄機制 8
2.2.5 其他改進串流品質的方式 10
2.3 比較不同的品質改進機制 10
2.4 本論文的影音串流改進機制 10
第三章 I-EPD架構與運作機制 12
3.1 中間節點的佇列滿載 12
3.2 Jitter與過期封包 13
3.2.1 Jitter的異常變化 13
3.2.2 判斷封包過期的方法 14
3.3 I-EPD運作方式 16
3.3.1 壅塞發生的情況 16
3.3.2 下游節點斷線的情況 20
3.3.3 I-EPD演算法 20
3.3.3.1 啟動I-EPD 20
3.3.3.2 I-EPD啟動後IN判斷封包的即時性 23
3.3.3.3 結束I-EPD機制 25
第四章 Linux實作與效能量測 26
4.1 Linux平台實作 26
4.1.1 中間節點新增的核心模組 26
4.1.2 伺服器端新增的部分 29
4.1.3 接收端新增的部分 30
4.1.4 背景資料流產生方式 32
4.2 實驗拓樸與設備 33
4.3 效能參數 35
4.4 實驗結果與分析 37
4.4.1 實驗參數設定 37
4.4.2 網路發生壅塞的情況 38
4.4.3 下游路徑斷線的情況 46
第五章 結論與未來工作 49
5.1 結論 49
5.2 未來工作 51
REFERENCES 53
附錄A 58
Index 59

[1] MPEG-4 Video Group, “MPEG-4 Overview-(V.21-Jeju Version),” ISO/IEC JTC1/SC29/WG11 N4668, Mar. 2002.
[2] Y. Kikuchi, T. Nomura, S. Fukunaga, Y. Matsui, and H. Kimata, “RTP Payload Format for MPEG-4 Audio/Visual Streams,” RFC 3016, Nov. 2000.
[3] Lihong Xu and Shuhua Ai, “A New Feedback Control Strategy of Video Transmission Based on RTP,” IEEE Conference on Industrial Electronics and Applications, pp.1-4, May 2006.
[4] M. Borri, A. Ferrarini, and M.L. Merani, “RTP-Primal: A New Congestion Control Scheme Suitable for Smooth Multimedia Delivery,” IEEE Wireless Communications and Networking Conference, pp.3752-3757, March 2007.
[5] Zhixiong Liu, Guiming He, and Zhensheng Liu, “An Adaptive Control Scheme for Real-time MPEG4 Video over Ad-hoc Networks,” International Conference on Wireless Communications, Networking and Mobile Computing, Vol. 2, pp.23-26, Sept. 2005.
[6] Shafqaat Ahmad, N .D Gohar, and Aatif kamal, “A Dynamic Congestion Control Mechanism for Real Time Streams over RTP,” International Conference on Advanced Communication Technology, Vol. 2, pp.961-966, Feb. 2007.
[7] Hamid Gharavi, “Control Based Mobile Ad-hoc Networks for Video Communications,” IEEE Transactions on Consumer Electronics, Vol. 52, Issue 2, pp.383-391, May 2006.
[8] Hsien-Po Shiang and Mihaela van der Schaar, “Multi-User Video Streaming Over Multi-Hop Wireless Networks: A Distributed, Cross-Layer Approach Based on Priority Queuing,” IEEE Journal on Selected Areas in Communications, Vol. 2, Issue 4, pp.770-785, May 2007.
[9] Haitao Wu, Yunxin Liu, Qian Zhang, Senior Member, and Zhi-Li Zhang, “SoftMAC: Layer 2.5 Collaborative MAC for Multimedia Support in Multihop Wireless Networks,” IEEE Transactions on Mobile Computing, Vol. 6, Issue 1, pp.12-25, Jan. 2007.
[10] Xu Chen, Sun Qiang, Zhang GuoAn, and Bao ZhiHua, “A Novel Framework for QoS Enhancement in Ad Hoc Network,” International Conference on Wireless Communications, Networking and Mobile Computing, pp.1-4, Sept. 2006.
[11] Wei Liu, Xiang Chen, Yuguang Fang, and John M. Shea, “Courtesy Piggybacking: Supporting Differentiated Services in Multihop Mobile Ad Hoc Networks,” IEEE Transactions on Mobile Computing, Vol. 3, Issue 4, pp.380-393, Oct.-Dec. 2004.
[12] Guillermo Diaz Delgado, Victor Carrascal Frias, and Monica Aguilar Igartua, “Video-streaming Transmission with QoS over Cross-Layered Ad hoc Networks,” International Conference on Software in Telecommunications and Computer Networks, pp.102-106, Sept. 2006.
[13] Shiwen Mao, Dennis Bushmitch, Sathya Narayanan, and Shivendra S. Panwar, “MRTP: A Multiflow Real-time Transport Protocol For Ad Hoc Networks,” IEEE Transactions on Multimedia, Vol. 8, Issue 2, pp.356-369, April 2006.
[14] Shiwen Mao, Shunan Lin, Shivendra S. Panwar, Yao Wang, and Emre Celebi, “Video Transport over Ad Hoc Networks: Multistream Coding with Multipath Transport,” IEEE Journal on Selected Areas in Comm., Vol. 21, Issue 10, pp.1721-1737, Dec. 2003.
[15] Kultida Rojviboonchai, Fan Yang, Qian Zhang, Hitoshi Aida, and Wenwu Zhu, “AMTP: A Multipath Multimedia Streaming Protocol for Mobile Ad Hoc Networks,” IEEE International Conference on Communications, Vol. 2, pp.1246-1250, May 2005.
[16] Masayuki Tauchi, Tetsuo Ideguchi, and Takashi Okuda, “Ad-hoc Routing Protocol Avoiding Route Breaks Based on AODV,” Proceedings of The 38th Hawaii International Conference on System Sciences, pp.322-329, Jan. 2005.
[17] Sergio Crisostomo, Susana Sargento, Pedro Brandao, and Rui Prior, “Improving AODV with Preemptive Local Route Repair,” International Workshop on Wireless Ad-Hoc Networks, pp.223-227, June 2004.
[18] Jing Feng and Huaibei Zhou, “A Self-Repair Algorithm for Ad Hoc On-Demand Distance Vector Routing,” International Conference on Wireless Communications, Networking and Mobile Computing, pp.1-4, Sept. 2006.
[19] Michael Pan, Sheng-Yan Chuang, and Sheng-De Wang, “Local Repair Mechanisms for On-Demand Routing in Mobile Ad hoc Networks,” The 11th Pacific Rim International Symposium on Dependable Computing, pp.1-8, Dec. 2005.
[20] Min-Gu Lee and Sunggu Lee, “QoS Support for Mobile Ad-Hoc Networks Based on a Reservation Pool,” IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing, pp.8-15, 2006.
[21] Jin Lian, Layuan Li, and Xiaoyan Zhu, “A Multi-constraint QoS Routing Protocol with Route-Request Selection Based on Mobile Predicting in MANET,” International Conference on Computational Intelligence and Security Workshops, pp.342-345, Dec. 2007.
[22] YuHua Yuan, Huimin Chen, and Min Jia, “ An Adaptive Load-balancing Approach for Ad Hoc Networks,” International Conference on Wireless Communications, Networking and Mobile Computing, Vol. 2, pp.743-746, Sept. 2005.
[23] Yang Xiao and Haizhon Li, “Local Data Control and Admission Control for QoS Support in Wireless Ad Hoc Networks,” IEEE Transactions on Vehicular Technology, Vol. 53, Issue 5, pp.1558-1572, Sept. 2004.
[24] Yaling Yang and Robin Kravets, “Contention-Aware Admission Control for Ad Hoc Networks,” IEEE Transactions on Mobile Computing, Vol. 4, Issue 4, pp.363-377, July-Aug. 2005.
[25] Ahmed Mehaoua, Raouf Boutaba, and Youssef Iraqi, “Partial Versus Early Packet Video Discard,” IEEE Global Telecommunications Conference, Vol. 1, pp.83-88, Nov. 1998.
[26] Maurizio Casoni and Jonathan S. Turner, “On the Performance of Early Packet Discard,” IEEE Journal on Selected Areas in Communications, Vol. 15, Issue 5, pp.892-902, June 1997.
[27] Kenji Kawahara, Koichiro Kitajima, Tetsuya Takine, and Yuji Oie, “Packet Loss Performance of Selective Cell Discard Schemes in ATM Switches,” IEEE Journal on Selected Areas in Communications, Vol. 15, Issue 5, pp.903-913, June 1997.
[28] Yonghwan Kim and San-qi Li, “Performance Analysis of Data Packet Discarding in ATM Networks,” Transactions on Networking, IEEE/ACM, Vol. 7, Issue 2, pp.216-227, April 1999.
[29] Pedro Cuenca, Antonio Garrido, Francisco Quiles, and Luis Orozco-Barbosa, “Performance Evaluation of Cell Discarding Mechanisms for the Distribution of VBR MPEG-2 Video over ATM Networks,” IEEE Transactions on Broadcasting, Vol. 44, Issue 2, pp.206-215, June 1998.
[30] Sheng-Tzong Cheng and Jian-Liang Lin, “Reliable Video Transmission Techniques for Wireless MPEG-4 Streaming Systems,” International Symposium on Dependable Computing, pp.248-258, Dec. 2006.
[31] Shihong Zou, Haitao Wu, and Shiduan Cheng, “A New Mechanism of Transmitting MPEG-4 Video in IEEE 802.11 Wireless LAN with DCF,” International Conference on Communication Technology Proceedings, Vol. 2, pp.1226-1229, April 2003.
[32] Mahasweta Sarkar, Supraja Gujral, and Sunil Kumar, “A QoS-Aware Medium Access Control Protocol for Real Time Traffic in Ad Hoc Networks,” IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, pp.1-5, Sept. 2007.
[33] Tien Pham Van, “Efficient Relaying of Video Packets over Wireless Ad hoc Devices,” IEEE Annual Wireless and Microwave Technology Conference, pp.1-5, Dec. 2006.
[34] Hyung Su Lee, Hee Young Youn, and Hye Dong Jung, “Packet Control Mechanism for Seamless Multimedia Streaming Service in Wireless Network,” International Conference Advanced Communication Technology, Vol. 3, pp.6-11, Feb. 2006.
[35] Rajiv Malik, Alka Munjal, and Shampa Chakraverty, “Adaptive Forward Error Correction (AFEC) based Streaming using RTSP and RTP,” International Conference on Telecommunications - International Conference on Internet and Web Applications and Services/Advanced (AICT-ICIW), pp.60-65, Feb. 2006.
[36] K. Ramakrishnan, TeraOptic Networks, S. Floyd, ACIRI, D. Black, and EMC, “The Addition of Explicit Congestion Notification (ECN) to IP Status of this Memo,” RFC 3168, Sept. 2001.
[37] Darwin Streaming Server - http://dss.macosforge.org/.
[38] VLC Media Player - http://www.videolan.org/.
[39] LIVE555 Streaming Media - http://www.live555.com/liveMedia/.
[40] Iperf - http://dast.nlanr.net/Projects/Iperf/.
[41] FFmpeg - http://ffmpeg.mplayerhq.hu/.
[42] JVT. Joint Scalable Video Model Reference Software. JSVM 9.8, Oct. 2007.