臺灣博碩士論文加值系統

本論文考量高壓縮效率的H.264視訊於無線網路802.11上的傳輸研究，利用即時從無線網路偵測的通道狀況參數，加上跨層的技術來達到以最小的能量消耗來改變視訊品質。在調整視訊品質(PSNR)的方法有二，方法一：改變位元率(bits rate)，即改變量化參數(QP)；方法二：改變基地台訊號雜訊比(SNR)，即改變移動端的發射功率(Pt)。這兩種方式都會影響能量的消耗，我們提出新的門檻值判斷方法來判斷使用方法一或是方法二能夠以較省電的方式，調整視訊達到指定的視訊品質(PSNR)。另外，針對這套在固定距離使用的門檻值判斷方法，延伸出可以在不同距離適應性調控策略，達到節省能耗提升移動無線攝影機的工作時間。根據我們論文所提出的方法在Foreman和Stefan視訊中能量可以降低16.58%~23.48%。

Video communication over wireless links using handheld devices is a challenging task due to the time-varying characteristics of the wireless channels and limited battery resources. Cross-layer technology plays a key role in video coding and communication systems, using this technology we can save power consumption effectively. In this paper, we consider two cross-layer parameters namely quantization Parameter (QP) of H.264 video codec in the application layer and wireless transmitting power in the physical layer for power saving in a H.264 based video surveillance system. This technique is based on the observation that a given video quality in the surveillance monitor can be achieved by either adjusting the QP (bit-rates) in video codec or adjusting the wireless transmitting power in the wireless video camera at different power consumption. We then derive a judgment technique to adjust either QP or transmitting power at lower energy cost for the same assigned video quality. Experiments on Foreman and Stefan sequences show that our method can save 16.58%~23.48% of energy.

中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 viii
第一章 緒論 1
1.1 研究背景 1
1.1.1 H.264 1
1.1.2 無線網路 2
1.2 研究問題 3
1.3 研究方法 4
1.4 論文主要貢獻 4
1.5 各章提要 4
第二章 背景 6
2.1 無線視訊通訊網路 6
2.2 802.11B無線網路 7
2.3 無線視訊IP網路協定 7
2.3.1 應用層(application layer) 8
2.3.2 傳輸層(transport layer) 11
2.3.3 網路層(network layer) 13
2.3.4 媒體存取控制層(media access control layer) 13
2.3.5 實體層(physical layer) 14
2.4 H.264視訊壓縮標準 14
2.4.1 H.264 視訊編碼層(video coding layer, vcl) 16
2.4.2 H.264 網路抽象層(network abstraction layer, nal) 18
2.5 有關無線視訊傳輸電池能量消耗的解決方法 18
第三章 H.264無線視訊品質調整之省電操作探討 21
3.1 H.264無線視訊監控的環境架構 21
3.2 實驗平台、實驗步驟與參數設定 22
3.2.1 實驗平台 22
3.2.2 實驗步驟 23
3.2.3 參數設定 24
3.3 問題描述 25
3.3.1 視訊品質與電池能量消耗關係分析 25
3.3.2 問題描述 27
3.4 依實驗數據所歸納出的調控方法 29
第四章 門檻值判斷與不同距離適應性調控策略 35
4.1 門檻值( )判斷方法 35
4.1.1 固定門檻值 35
4.1.2 適應性門檻值 41
4.2 不同距離適應性調控策略 43
4.2.1 監控介面與初始設定 47
4.2.2 調整視訊品質 49
4.3移動端電池能量消耗比較 54
第五章 結論與未來研究方向 61
參考文獻 62

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