以透過無線網路的影像串流而言會因無線網路的情況造成較大之影響，比如說所使用通道的頻寬限制或是網路頻寬的變化量情況等，可能會造成透過無線網路時用使用者裝置時播放的情況不很理想，從這一方面而言，當發生頻寬下降的情況下，一個較低畫質但是平滑的播放會比較高畫質可是會失真的情況要好，藉著這個推論，我們提出了一個機制Transmission-Rate Adapted Streaming Server (TRASS)，放在影像伺服器跟使用者裝置中間，以根據實際上的傳輸速率調整成適合的影像品質，以所提出的辦法中使用者裝置會回饋網路的狀況給Transmission-Rate Adapted Streaming Server (TRASS)，Transmission-Rate Adapted Streaming Server (TRASS)會藉由這些回饋調整影像到適合的品質，並且本篇提出了一個理論分析，接著在模擬時利用了兩種編碼方式MPEG-4 和 H.264/AVC來驗證當網路傳輸速率發生變化時本架構可有效的使在使用者端的視訊播放更順暢也有比較低的封包掉落率，當使用者的網路傳輸速率降低時，降低了導致使用者觀感變差的情況發生的機會。

Video streaming quality in a wireless communication network environment is largely affected by various network characteristics, such as a limited channel bandwidth and a variant transmission rate. The playback quality on User Equipments (UEs) may not be smooth when the service is delivered via a wireless environment. From the viewpoints of most video receivers, a smooth playback with a lower video quality may be more significant than a lagged or distorted playback with a higher video quality as the transmission rate degrades. Based on above, we sketch an adaptation agent - Transmission-Rate Adapted Streaming Server (TRASS), which is located between the original video server and UEs, to adaptively transform the streaming video based on the real transmission rate. In our proposed scheme, UEs would feed back their network access statuses to TRASS and then TRASS would deliver adaptive quality of video streams to UEs according to their feedbacks. The theoretical analysis and simulations using different video tracks encoded in MPEG-4 and H.264/AVC formats show that TRASS can help wireless streaming users get a smooth playback quality with a lower packet failure rate. With a low probability of receiving a worse quality of video, users’ Quality of Experience (QoE) can subsequently be raised.

[1] P. Soohong and J. Seong-Ho, "Mobile IPTV: Approaches, Challenges, Standards, and QoS Support," Internet Computing, IEEE, vol. 13, pp. 23-31, 2009.
[2] J. Asghar, et al., "Preserving Video Quality in IPTV Networks," Broadcasting, IEEE Transactions on, vol. 55, pp. 386-395, 2009.
[3] E. A. Jammeh, et al., "Interval Type-2 Fuzzy Logic Congestion Control for Video Streaming Across IP Networks," Fuzzy Systems, IEEE Transactions on, accepted for future publication, 2009.
[4] Z. Yingnan, et al., "High Performance Adaptive Video Services Based on Bitstream Switching for IPTV Systems," in Consumer Communications and Networking Conference, 2009. CCNC 2009. 6th IEEE, 2009, pp. 1-5.
[5] C. Bouras, et al., "Adaptive smooth multicast protocol for multimedia transmission: Implementation details and performance evaluation," International Journal of Communication Systems, vol. 23, pp. 299-333, 2010.
[6] O. B. Karimi and M. Fathy, "Adaptive end-to-end QoS for multimedia over heterogeneous wireless networks," Computers & Electrical Engineering, vol. 36, pp. 45-55, 2010.
[7] Z. Orlov, "Network-driven adaptive video streaming in wireless environments," in Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on, 2008, pp. 1-6.
[8] P. Jae-Young, "Context-Aware Streaming Video System for Vertical Handover over Wireless Overlay Network," Consumer Electronics, IEEE Transactions on, vol. 54, pp. 71-79, 2008.
[9] B. Xie and W. Zeng, "Fast Bitstream Switching Algorithms for Real-Time Adaptive Video Multicasting," Multimedia, IEEE Transactions on, vol. 9, pp. 169-175, 2007.
[10] J.-S. Leu and C.-W. Tsai, "Practical Design of a Proxy Agent to Facilitate Adaptive Video Streaming Service across Wired/Wireless Networks," Journal of Systems and Software , vo1. 82, issue 11, pp. 1916-1925, Nov. 2009.
[11] D. Chattopadhyay, et al., "Adaptive rate control for H.264 based video conferencing over a low bandwidth wired and wireless channel," in Broadband Multimedia Systems and Broadcasting, 2009. BMSB 2009. IEEE International Symposium on, 2009, pp. 1-6.
[12] K. Jinsul, et al., "IPTV Systems, Standards and Architectures: Part II - Heterogeneous Networks and Terminal-Aware QoS/QoE-Guaranteed Mobile IPTV Service," Communications Magazine, IEEE, vol. 46, pp. 110-117, 2008.
[13] “Network Simulator 2”, available on http://www.isi.edu/nsnam/ns/ 2010
[14]“EvalVid - A Video Quality Evaluation Tool-set”, available on http://www.tkn.tu-berlin.de/research/evalvid/ 2010
[15] ITU-T, Principles of a reference impairment system for video, ITU-T Recommendation P.930, 08/1996
[16] ITU-T, Methods for subjective determination of transmission quality, ITU-T Recommendation P.800, 1996
[17] J. Klaue, B. Rathke, A. Wolisz, “EvalVid - A Framework for Video Transmission and Quality Evaluation”, Proc. 13th Conference on Modelling Techniques and Tools for Computer Performance Evaluation, USA, Sept. 2003
[18] “FFmpeg”, available on http://ffmpeg.org/ 2010
[19] “H.264/AVC Software Coordination, The latest H.264/AVC reference software”, available on http://iphome.hhi.de/suehring/tml/ 2010