一個串流影片是由影像幀所組成的，這些影像幀可以被分類為重要程度不同的幾個類型。在這個研究裡，我們的目標是要藉由增進重要影像幀之成功傳輸率而去提昇使用者的經驗品質。我們的方法是設計在LTE-A的網路下，並且會依據重要程度的不同去分配不同的編碼方式給影像幀。問題公式化考慮在同一個圖像群組裡面之影像幀的類型、彼此參考的關係、以及串流中的順序，並考慮一些延遲限制以及物理的限制下，去最大化可以成功接收到的影片大小，然而此類問題是屬於MINLP (mixed integer nonlinear problem)，這類的問題在規模較大時是屬於NP-hard。因此我們提出一個演算法去決定每個影像幀的編碼以及配置，在結果模擬中，我們使用峰值訊噪比去量測我們方法的效能，實驗模擬結果顯示，我們方法的效能在相同資源情境以及充足資源情境下皆優於其他方法。

A stream of video is composed of frames, which can be categorized into frame types of different importance. In this research, we aim to improve the Quality of Experience (QoE) perceived by user via improving the rate of successful transmission for important video frames. Our method is designed for 4G LTE-A networks. Different modulation and coding schemes (MCSs) are assigned to frames based on the degree of the importance. The downlink radio resource scheduling problem is formulated with the considerations of frame type and reference relation between frames of the same group of picture (GOP). The formulation aims to maximize the average expected weighted successful transmission size, while considering the delay constraint for video frames. However, this formulation is a mixed integer nonlinear problem (MINLP), which is proved to be NP-hard. Therefore, we propose a heuristic algorithm to determine the transmission order and the MCS level for each video frame. In simulation, we measure Peak Signal Noise Ratio (PSNR) to evaluate the performance of our proposed method comparing to the methods proposed in existing literature. The evaluation shows that the PSNR value of the proposed method is higher than those of the conventional adaptive method 2.35 dB and 5.27 dB on average in the scenario with the same resources and in the sufficient bandwidth condition respectively.

[1] “Cisco visual networking index: Global mobile data traffic forecast update, 2013-2018.” White Paper, Cisco, Feb 2014.
[2] Video trace library. [Online]. Available: http://trace.eas.asu.edu/index.html
[3] The moving picture experts group (mpeg). [Online]. Available: http://mpeg.chiariglione.org/standards/mpeg-4/
[4] Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 12), 3GPP Std. TS 36.211, 2013.
[5] J. Zyren, “Overview of the 3gpp long term evolution physical layer,” Freescale Semiconductor, Tech. Rep., 2007.
[6] S. Arawvith and M.-T. Sun, “Mpeg-1 and mpeg-2 video standards,” Handbook of Image and Video Processing, 2000.
[7] Advanced Video Coding for Generic Audiovisual Services, Rec- ommendation H.264 and ISO/IEC 14496-10 (MPEG-4) AVC, International Telecommunication Union-Telecommun. (ITU-T) and International Standards Organization/International Electrotechnical Commission (ISO/IEC) Std. 14496-10, 2003.
[8] Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification, 3GPP Std. TS 36.321, 2011
[9] M. Ismail, W. Zhuang, and S. Elhedhli, “Energy and content aware multi-homing video transmission in heterogeneous networks,” IEEE Transations on Wireless Communications, vol. 12, pp. 3600–3610, July 2013.
[10] P. Bonami, M. Kilinc, and J. Linderoth, “Algorithms and software for convex mixed integer nonlinear programs,” Computer Sciences Department, University of Wisconsin-Madison, Tech. Rep., 2009.
[11] M. R. Garey and D. S. Johnson, Computers and intractability: A guide to the theory of np-completeness. W. H. Freeman and Company, 1979.
[12] R. Fourer, D. M. Gay, and B. W. Kernighan, AMPL: A Mathematical Programming Language. Brooks/Cole-Thomson Learning, 2003.
[13] P. Belotti, “Couenne: a users manual.” Lehigh University, Tech. Rep., 2009. [Online]. Available: http://www.coin-or.org/Couenne/
[14] J. C. Ikuno, M. Wrulich, and M. Rupp, “System level simulation of LTE networks,” in Proceedings of the IEEE Vehicular Technology Conference, Taipei, Taiwan, May 2010.
[15] FFmpeg. [Online]. Available: http://ffmpeg.org/
[16] S. H. Kang and A. Zakhor, “Packet scheduling algorithm for wireless video streaming,” in Proceedings of the Packet Video, April 2002.
[17] J. Klaue, B. Rathke, and A. Wolisz, “Evalvid - a framework for video transmission and quality evaluation,” in Proceedings of the 13th Conference on Modelling Techniques and Tools for Computer Performance Evaluation, USA, September 2003.
[18] J. Seppanen and M. Varela, “Qoe-driven network management for real-time over-the-top multimedia services,” in Proceedings of the IEEE Wireless Communications and Networking Conference, 2013.
[19] P. L. Callet, S. Moller, and E. A. Perkis. (2012) Qualinet white paper on definitions of quality of experience. [Online]. Available: http://www.qualinet.eu/images/stories/
[20] Methodology for the subjective assessment of the quality of television pictures, ITU-R Std. BT.500-10., 2000.
[21] Digital transport of one-way video signals - parameters for objective performance assessment, ANSI Std. T1.801.03-1996., 1996.
[22] A. Balasubramanian, L. Ma, A. Rapaport, W. Liu, G. Sternberg, and A. Zeira, “Intra-stream traffic differentiation and resource allocation for video teleconferencing in lte systems,” in Proceedings of the IEEE International Workshop on Multimedia Signal Processing, September 2013.
[23] J. Yoon, H. Zhang, S. Banerjee, and S. Rangarajan, “Muvi: A multicast video delivery scheme for 4g cellular networks,” in Proceedings of the ACM International Conferencem on Mobile Computing and Networking, 2012.
[24] A. Pande, V. Ramamurthi, and P. Mohapatra, “Quality-oriented video delivery over LTE using adaptive modulation and coding,” in Proceedings of the IEEE Global Telecommunications Conference, Dec 2011, pp. 1–5.
[25] J. Currie and D. I. Wilson, "OPTI: Lowering the Barrier Between Open Source Optimizers and the Industrial MATLAB User," Foundations of Computer-Aided Process Operations, Georgia, USA, 2012.