多媒體封包在無線通道傳送經常會因為通道的衰退或壅塞造成封包遺失，使得在解碼端的畫質下降。在H.264中，可利用插入畫面內區塊，而在IEEE802.16e中可利用通道編碼，來克服解碼端品質衰退的問題。首先，我們建立出包含畫面內區塊更新率之位元率-失真模型與IEEE802.16e之端對端失真模型，並且利用這些模型以即時預測出畫面位元率和失真的變化，然後調適性地選擇出最佳之更新率及編碼調變之方式，使得在解碼端的畫質保持在最佳的表現。實驗結果顯示，採用我們所提出的調適性方式與固定方式相比，在解碼端有比較好的PSNR表現。

When multimedia packets are transmitted in wireless channels, they are often lost because of channel congestion or fading. This loss usually results in quality degradation of video. Intra macroblocks (MBs) in H.264 and channel coding in IEEE 802.16e can be exploited to combat this problem. We first establish a rate-distortion model with different intra MB refresh rates and an end-to-end distortion model of IEEE802.16e. These models then are employed to estimate bit rate and distortion in real time. Finally, we adaptively select the optimal refresh rate, code rate, and modulation to obtain the best video quality. Computer simulations show the PSNR of our proposed adaptive method is better than the method with a fixed setting.

[1] S. Wenger, “H.264/AVC over IP,” IEEE Trans. Circuits System Video Technology, vol. 13, pp. 645–656, July 2003.
[2] T. Wiegand, G. J. Sullivan, G. Bjøntegaard, and A. Luthra, “Overview of the H.264/AVC video coding standard,” IEEE Trans. Circuits System Video Technology, vol. 13, pp. 560–576, July 2003
[3] IEEE Standard for Local and metropolitan area networks, Part 16: air interface for fixed broadband wireless access systems, IEEE Std. 802.16-2004, 2004.
[4] H. Sari, G. Karam, and I. Jeanclaude, “Transmission techniques for digital terrestrial TV broadcasting,” IEEE Comm. Mag., vol. 42, pp. 100–109, Feb. 1995.
[5] R. Van Nee and R. Prasad, OFDM for Wireless Multimedia Communications, Norwood, MA: Artech House, 2000.
[6] IEEE Standard for Local and metropolitan area networks, Part 16: air interface for fixed broadband wireless access systems, Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, IEEE Std. 802.16e, 2005.
[7] H. Yaghoobi, “Scalable OFDMA physical layer in IEEE 802.16 WirelessMAN,” Intel Technology J., vol. 8, pp. 201-212, Aug. 2004.
[8] L. Liu, S. Zhang, X. Ye, Yin Zhang, “Error resilience schemes of H.264/AVC for 3G conversational video services,” IEEE int. conf. computer and information technology , pp.657-661, Sep 2005
[9] T. Stockhammer, M. Hannuksela, and T.Wiegand, “H.264/AVC in wireless
environments,” IEEE Trans. Circuits System Video Technology, vol. 13,
pp. 657–673, Jul 2003
[10] K. Stuhlmuller, N. Farber, M. Link and B. Girod, “Analysis of video transmission over lossy channels,” IEEE journal on selected Areas in communications, vol. 18, pp. 1012-1032, Jun 2000
[11] Z. He, J. Cai, and C. W. Chen, “Joint source channel rate-distortion analysis for adaptive mode selection and Rate control in wireless video coding,” IEEE Trans. Circuits System Video Technology, vol. 12, pp.511-523, Jun 2002
[12] Z. He, Y. Kim, and S. K. Mitra, “A novel linear source model and a unified rate control algorithm for H.263/MPEG-2/MPEG-4,” in Proc. Int. Conf. Acoustics, Speech, and Signal Processing, Salt Lake City, UT, May 2001.
[13] J. Ribas-Corbera and S. Lei, “Rate control in DCT video coding for low delay communications,” IEEE Trans. Circuits System Video Technology, vol. 9, pp.172–185, Feb 1999
[14] H. M. Hang and J.J. Chen , “Source model for transform video coder and its application. I. Fundamental theory,” IEEE Trans. Circuits System Video Technology,Vol.7, pp.:287 - 29, Apr 1997
[15] S. Shuguang, Y. Shengsheng and Z. Jingli, “An improved Basic-Unit layer Rate-Control scheme on H.264,” IEEE Int. Conf. Parallel and Distributed Computing, Applications and Technologies, pp.815–819, Dec. 2005
[16] E.Y. Lam and J.W. Goodman , “A mathematical analysis of the DCT coefficient distributions for images,” IEEE Trans. Image processing., vol. 9, pp.1661–1666, Oct. 2000
[17] R. Zhang, S. L. Regunathan, and K. Rose, “Video coding with optimal
inter/intra-mode switching for packet loss resilience,” IEEE journal on selected Areas in communications, vol. 18, pp. 966–976, Jun. 2000.
[18] Z. He and S.K. Mitra , “A unified rate-distortion analysis framework for transform coding,” IEEE Trans. Circuits System Video Technology, vol. 11, pp.1221–1236, Dec. 2001
[19] I. E. G. Richardson, H.264 And MPEG-4 Video Compression Video Coding For Next Generation Multimedia, Wiley, 2003, 1st ed
[20] G. L. Stüber, Principles of Mobile Communication, 2nd ed., Boston, MA: Kluwer Academic Publishers, 2001