利用迭代式三維馬可夫隨機場之無壓縮無線視訊傳輸系統的宏區塊非平等資料保護架構

A Macroblock Unequal Error Protection Scheme for Uncompressed Wireless Video Transmission Using Iterative 3D-MRF based Decoder

李柏希(Po-Hsi Lee)

指導教授 ： 葉丙成

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01651

摘要

由於能夠提供數Gbps大的無線網路傳輸頻寬57-66GHz高頻微波的發展，因此無壓縮的高解析度視訊傳輸成為了家用網路的一項受矚目應用。然而，在如此高的頻率之下，訊號波衰退的速率以及受到雜訊干擾的程度都大幅提升，因此如何在如此低訊噪比的傳輸通道進行傳輸顯得相當的重要。在本論文中，我們提出了一種在傳送端決定能量分配策略的非平等資料保護架構。我們提出的非平等資料保護架構是針對利用基於三維馬可夫隨機場模型的迭代無線視訊解碼系統所設計的，根據在一個位元層裡的不同宏區塊擁有不相同的空間和時間冗餘性，在發送端分配最佳的傳輸能量策略，以達到最佳的解碼品質。為了精準地分配傳輸能量，在傳送端我們也用了相似的馬可夫模型來預測每個宏區塊的資料冗餘性。接著進一步利用拉格朗日乘數法來解決在固定傳輸能量之下，最大化解碼品質的問題。模擬結果顯示，所提出的宏區塊非平等資料保護架構，根據影像的性質，或多或少提升了解碼的品質。我們也結合了位元層的非平等資料保護架構以及我們所提出的宏區塊資料保護架構。比較的結果顯示，所提出的宏區塊非平等資料保護架構在影像富含時間冗餘性時比起位元層的非平等資料保護架構表現較佳。

關鍵字

宏區塊 ； 非平等資料保護 ； 無線通訊 ； 視訊傳輸 ； 三維馬可夫隨機場

並列摘要

Due to the development of 57-66GHz millimeter-wave, which provides huge bandwidth and multi-Gbps transmission data rate, uncompressed high-definition video transmission is becoming an interesting application over wireless personal area networks (WPANs). However, mmWaves signals have more attenuation than conventional low frequency signals. Hence, wireless transmission under this low SNR condition become an issue. In this thesis, we proposed a unequal error protection (UEP) scheme which determines the power distributing policy according to the redundancy of a macroblock for iterative 3D-MRF based decoder. The 3D-MRF based source decoder utilizes the spatial and temporal redundancy for each macroblock split from a bit-plane. To allocate the transmission power accurately, the encoder estimates the decoded video quality using such MRF model to obtain spatial and temporal redundancy for all macroblocks before transmission. The optimal power allocation problem, which corresponds to maximizing video quality in term of peak-to-noise ratio (PSNR) is then solved by Lagrange multiplier. Simulation results show that the proposed macroblock UEP scheme enhances the decoded visual quality depending on the video properties and content. The bit-plane UEP scheme is also combined with our proposed macroblock UEP scheme. We observe that the proposed macroblock UEP performs better than bit-plane UEP when the transmission video is rich in temporal redundancy.

並列關鍵字

macroblock ； unequal error protection ； wireless communication ； iterative joint source-channel decoding ； Markov random fields

參考文獻

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