隨著無線行動通訊技術的演進，影像串流在這些年裡也進步了很多。然而因為行動裝置使用者通常一邊移動一邊播放串流影片，因此無線行動網路環境通常在可用頻寬上有很大的高低振盪。為了克服這種情況，我們提出了一個方法稱作「使用時間及地理位置進行頻寬估計方法之逐步自適性影音串流技術」，它是一組基於MPEG-DASH標準並適用於無線行動網路環境的自適性影音串流架構及控制方案。為了取得更好的用戶體驗(QoE)，本論文提出的方法在預測可用頻寬上考量到地理位置、日期及時段，並且在自適性串流控制方案上考慮了緩衝層級、最近下載的影像片段的品質、最近下載的影像片段的下載速率和預測可用頻寬來決定下一個要下載的影像片段的品質。本論文提出的方法已被實作出來，在客戶端上基於安卓(Android)系統，伺服器端則是基於Linux。本論文也展示了一個具代表性的通勤路徑的無線行動網路的可用頻寬分布，並揭露了該路徑具有高可用頻寬的同時在可用頻寬上也有著很大的高低振盪。使用本論文提出的方法進行的實驗展示了此方法在無線行動網路環境上的頻寬使用率、初始延遲時間、播放暫停次數、影像品質變動百分率、平均每影像片段的位元率變動、考量到播放暫停的平均位元率變動及位元率變動的標準差都有著效能改進。

With the advance of wireless mobile communication technologies, video streaming has advanced much more on these years. However, the wireless mobile networking environment usually suffers fluctuation in available bandwidth because mobile users usually keep moving and playing streaming video simultaneously. To overcome the situation, this work proposed a method called Stepwise Adaptive Streaming using Temporal-Geo Bandwidth Estimation (SASTGBE) used for the wireless mobile networking environment based on MPEG-DASH. To have better Quality Of Experience (QoE), the proposed method considers geo, date, and time concerns for estimating the available bandwidth in the future and the proposed adaptive streaming control scheme considers buffer level, video quality of the most recently downloaded segment, the downloading rate of the most recently downloaded segment and the estimated bandwidth to decide the video quality for the next downloaded segment. The proposed method has been implemented in the Android system for the client side and the Linux system for the server side. The experiments using SASTGBE in the real environment shown that SASTGBE has improvement in the performance of bandwidth utilization, initial delay time, suspended times, quality switch percentage, bitrate difference per segment, average bitrate difference considering suspending, and standard deviation of bitrate difference over the wireless mobile network.

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