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    題名: H.264/AVC影像規格於IEEE 802.16網路環境中優先權等級指派之研究
    其他題名: The research of priority assignment for H.264/AVC video transmission in IEEE 802.16 networks
    作者: 李柏毅;Lee, Po-i
    貢獻者: 淡江大學電機工程學系碩士班
    李維聰;Lee, Wei-tsong
    關鍵詞: IEEE 802.16;H.264/AVC;服務品質;優先權指派;IEEE 802.16;H.264/AVC;QoS;Priority Assignment
    日期: 2007
    上傳時間: 2010-01-11 07:07:05 (UTC+8)
    摘要: 隨著無線網路技術的進步以及應用層面的擴展,除了檔案的傳輸、下載等基本的應用外,各式各樣的即時性服務也開始結合了無線網路的傳輸。使用者希望能夠在隨時隨地,不需利用有線傳輸的方式來得到影音的下載 或即時互動。這些應用包含了:視訊電話、視訊會議、數位電視及串流媒體播放等等,這些運用在頻寬有限的情況下,希望在即時性(Real time)和影像品質的取捨間做到兼顧的情況。基於這樣的需求,也就有越來越新穎的技術被提出。
    IEEE 802.16-2005中提出了五種等級傳送的機制,包括:非請求的頻寬分配 (UGS)、延伸即時可變速率服務(ERT-VR)、即時可變速率服務(RT-VR)、非即時可變速率服務(NRT-VR)、盡力式傳送(BE)。這五項服務等級的提出,也使得各種類的應用在傳輸時,可以依照其所對應的等級來送出資料,讓資料更適合用於無線網路中傳輸。
    而本論文在採用的多媒體壓縮技術-H.264/AVC,其定義了三種不同的Profile:Baseline Profile著重在視訊電話,視訊會議等偏重即時傳輸等服務類別,Main Profile重點則是電視的播放以及影像儲存的應用,而Extension Profile則是在串流媒體的播放上提供了較多的技術支援。H.264/AVC並且率先提出了網路提取層 (Network Abstraction Layer)的概念,影像在視訊編碼層(Video Coding Layer)完成編碼之後,移交到網路提取層中,而網路提取層會依視訊編碼層產生的編碼內容將其封裝近NAL units,並給予應有的標頭資訊。
    本研究的主要內容,就是透過這些標頭的參數定義,讓視訊編碼層的資料更適合網路內傳輸,依照其內容定義傳輸時的等級區別,讓即時的多媒體資料在放進無線網路傳輸之前的,先依照等級制度給予優先權的指派,之後再放入IEEE 802.16-2005中特別設計給即時資料傳輸的RT-VR中傳送。在無線網路頻寬有限的環境下,儘可能的將頻寬指派給重要性較高的資料傳輸,如此便達到分級傳送的目的。並在模擬中測試各等級的資料,在不同遺失率下的遺失情況。
    With the fast progress of the wireless networking technique and the extension of its application, lots of real-time services in addition to the transmission and downloading applications start to use the wireless network transmission. Those applications include video telephony, video conferencing, digital TV, streaming media application, etc, which should be considered with the trade-off between the real time and the image quality under the limited bandwidth. According to such demands, more and more novel techniques are proposed.
    There are five levels of transmission mechanism in IEEE 802.16-2005, including Unsolicited Grant Service (UGS), extended real time Polling-Variable Rate Service (ert-VR), real time Polling-Variable Rate Service (rt-VR), non real time Polling-Variable Rate Service (nrt-VR), and Best Effort (BE). With the presentation of these five service levels, the data will be transmitted according to corresponding levels, and will be more suitable in wireless transmission.
    This paper use H.264/AVC video transmission, which defines a set of three Profiles. Applications of the Baseline Profile include video telephony, video conferencing; applications of the Main Profile include television broadcasting and video storage; and the Extended Profile may be particularly useful for streaming media applications. H.264 proposes the idea of Network Abstraction Layer (NAL). The output of the encoding process of VCL data will be packeted into NAL units. The NAL will give the NAL units corresponding header information according the contents of the units.
    This main research is to make the data of VCL transmit in network better by the parameters of NAL headers. According to the designed levels, the real-time multimedia information will be assigned with the priority of the ranking before transmission, and then transmitted in RT-VR of IEEE 802.16-2005.
    In the circumstance with the finite bandwidth in wireless network, we try the best to assign the bandwidth to the transmission of data with higher priority for transmission ranking. We simulate the situations of the data in all ranks under different loss rate.
    顯示於類別:[電機工程學系暨研究所] 學位論文

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