這篇論文主要是在現有的IEEE 802.11e無線網路架構上，針對影像串流提出一個傳輸保護機制。在我們所提出的Cross-Layer Mapping Unequal Error Protection (CLM-UEP) 機制中，利用不等錯誤保護 (UEP) 方式針對影像資料的重要性給予不同等級的傳輸保護以對抗無線網路傳輸所造成的封包遺失，並結合動態跨層對應演算法 (Cross-Layer Mapping)，充分利用佇列空間以降低產生影像保護封包所引起的網路擁塞問題，進而達到改善影像在無線網路上的傳輸品質。利用階層式影像編碼技術的特性，將不同種類的影像封包在應用層 (Application Layer) 產生的重要性，予以不同等級的傳輸錯誤保護。接著當影像封包與保護封包往下傳輸至媒體存取控制層 (Media Access Control) 時，針對影像封包在編碼上的重要性，給予不同的佇列對映方式，提高重要的影像封包優先傳送機率，並且對目前網路負載的情形做動態的判斷，將不同重要性的影像與保護封包指派到最適合的佇列中，希望能藉此更有效地利用網路資源，以減少網路發生擁塞遺失 (congestion loss) 。透過實驗數據比較和分析顯示，我們所提出來的機制除了能有效對抗無線傳輸所造成的封包遺失，而且還可以有效利用佇列空間避免網路壅塞，並經由給予不同重要性的影像封包優先次序，改善影像傳輸的品質。

This thesis is mainly proposing a protection mechanism for video streaming over IEEE 802.11e wireless network. In the proposed Cross-Layer Mapping Unequal Error Protection (CLM-UEP) mechanism, the lost packets caused by wireless transmission are against by employing Unequal Error Protection (UEP) which gives differential level of transmission protection based on the significance of video coding. Moreover, our proposing CLM-UEP adopts an adaptive Cross-Layer Mapping algorithm to effectively utilizes queue space and reduce the network congestion. According to hierarchical video coding features, the CLM-UEP scheme generates differential amounts of redundant packets to different video frame types in the Application Layer. After that, in the Media Access Control layer, the video and redundant packets are mapped to proper AC queues with a dynamic mapping method based on video coding significance and network load to achieve the higher transmission priority to the more important video and redundant packets. The numerical results show that our proposed CLM-UEP mechanism improves the video transmission quality over IEEE 802.11e network by reducing the wireless transmission loss with UEP, but also avoiding network congestion with adaptive queue mapping.

[1] "YouTube, http://www.youtube.com/."
[2] "Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amedment 8: Medium Access Control (MAC) quality of Service Enhancements," IEEE Standard 802.11e, 2005.
[3] P. Agrawal, et al., "IP multimedia subsystems in 3GPP and 3GPP2: overview and scalability issues," 2008.
[4] Y.-F. Huang and C.-Y. Chiu, "Dynamically adjusting MPEG4 video streams based on network bandwidth," Multimedia Tools Appl., vol. 36, pp. 267-284, 2008.
[5] A. Kantarc "Streaming of scalable h. 264 videos over the Internet," Multimedia Tools and Applications, vol. 36, pp. 303-324, 2008.
[6] H. Luo, et al., "Video streaming over the internet with optimal bandwidth resource allocation," Multimedia Tools Appl., vol. 40, pp. 111-134, 2008.
[7] Z. Naor, "Multicast video streaming for 4G wireless networks: Research Articles," Wirel. Commun. Mob. Comput., vol. 7, pp. 173-185, 2007.
[8] H. Sun, et al., "An overview of scalable video streaming," Wireless Communications and Mobile Computing, vol. 7, pp. 159-172, 2007.
[9] Q. Li and M. Van Der Schaar, "Providing adaptive QoS to layered video over wireless local area networks through real-time retry limit adaptation," IEEE Transactions on Multimedia, vol. 6, pp. 278-290, 2004.
[10] H. Du, et al., "Research on adaptive FEC for video delivery over WLAN," presented at the Proceedings of the 5th International Conference on Wireless communications, networking and mobile computing, Beijing, China, 2009.
[11] C. Lin, et al., "A RED-FEC mechanism for video transmission over WLANs," IEEE Transactions on Broadcasting, vol. 54, pp. 517-524, 2008.
[12] C. Lin, et al., "An Enhanced Adaptive FEC Mechanism for Video Delivery over Wireless Networks," 2006, pp. 106-111.
[13] M. Elaoud and P. Ramanathan, "Adaptive use of error-correcting codes for real-time communication in wireless networks," 1998, pp. 548-555.
[14] H. Seferoglu, et al., "Rate distortion optimized joint ARQ-FEC scheme for real-time wireless multimedia."
[15] J. Shih and W. Tsai, "A new unequal error protection scheme based on FMO," Multimedia Tools and Applications, vol. 47, pp. 461-476, 2010.
[16] H. Ha and C. Yim, "Layer-weighted unequal error protection for scalable video coding extension of H. 264/AVC," IEEE Transactions on Consumer Electronics, vol. 54, pp. 736-744, 2008.
[17] E. Maani and A. Katsaggelos, "Unequal Error Protection for Robust Streaming of Scalable Video Over Packet Lossy Networks," IEEE transactions on circuits and systems for video technology, vol. 20, pp. 407-416, 2010.
[18] H. Wu, et al., "Adjusting forward error correction with temporal scaling for TCP-friendly streaming MPEG," ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP), vol. 1, pp. 315-337, 2005.
[19] C. Design, "Toward an improvement of H. 264 video transmission over IEEE 802.11 e through a cross-layer architecture," IEEE Communications Magazine, pp. 107-114, 2006.
[20] C. Lin, et al., "An adaptive cross-layer mapping algorithm for MPEG-4 video transmission over IEEE 802.11 e WLAN," Telecommunication Systems, vol. 42, pp. 223-234, 2009.
[21] P. Ferre, et al., "A video error resilience redundant slices algorithm and its performance relative to other fixed redundancy schemes," Signal Processing: Image Communication, 2010.
[22] M. Tsai, et al., "Concurrent multipath transmission combining forward error correction and path interleaving for video streaming," Computer Communications, 2010.
[23] "NS simulator http://nsnam.isi.edu/nsnam/index.php/Main_Page."
[24] "NS-2 simulator, http://hpds.ee.ncku.edu.tw/~smallko/ns2/ns2.htm."
[25] "YUV video sequences (QCIF),
http://www.tkn.tu-berlin.de/research/evalvid/qcif.html."
[26] "ffmpeg, http://ffmpeg.sourceforge.net/index.php."
[27] D. Jiang and L. Delgrossi, "IEEE 802.11p: Towards an international standard for wireless access in vehicular environments," 2008, pp. 2036-2040.