應用於影像串流之可用頻寬偵測技術

Available Bandwidth Estimation Technology for Video Streaming

吳建明(Jian-Ming Wu)

指導教授 ： 朱元三

國立中正大學/工學院/電機工程學系/碩士(2014年)

摘要

由於近年來智慧型手機與平板電腦等行動裝置的便利性與普及性，加上無線網路技術的推陳出新，利用頻寬有限的無線網路在傳輸多媒體影像串流的服務愈趨普及，加上不同用戶端的網路可用頻寬不盡相同，因此頻寬偵測的機制是非常重要的，伺服器端利用頻寬偵測的資訊可讓用戶端達到高品質的服務。一個好的頻寬偵測機制需符合下列兩點：高準確性與低負擔性。準確的提供目前可用頻寬值以及不造成目前網路頻寬的額外負擔。

本論文提出自動頻寬偵測，可以封裝影像串流的檔案，做為探測封包傳送，故在實作上不需再傳送大量額外探測封包，以免造成網路負擔。自動頻寬偵測中提出的頻寬計算方法，可提升頻寬偵測的準確性，並針對在無線網路環境下不如有線環境穩定，往往會造成偵測結果的誤差，我們亦改善了此問題，最後實測得到，在有線網路環境下的頻寬誤差率為1.298%，無線網路環境下的誤差率為3.173%，相較於其他頻寬偵測工具準確。而且自動頻寬偵測僅造成少量的網路負擔，在30秒播放時間執行自動頻寬偵測1次的情形下期負載率為0.337%，偵測4次為1.463%，因此在播放多媒體影像串流時，進行自動頻寬偵測並不會造成影像延遲，亦不影響其流暢度。本論文的方法不管在有線網路環境或是在無線網路環境下，準確度與負載率皆優於其他頻寬偵測的工具。

關鍵字

可用頻寬偵測 ； IEEE 802.11

並列摘要

In recent years, the service of multimedia transmission becomes universal due to the rapid development of wireless networks. Smart phone and tablet PC become more and more popularization, bring more convenience to people. The transmission of video streaming service for wireless is becoming increasingly popular, and most have a compressed video stream into different specifications to meet users for different bandwidth demand. However, bandwidth detection mechanism is very important in the transmission of video streaming. Using the information of bandwidth detection will make the clients to be high-quality services. A good bandwidth detection mechanism should include the two following characters, accurate and no cost, which mean to provide available bandwidth accurately and fast detection without additional burden. The proposed bandwidth detection mechanism, which use the protocol of IEEE802.11 Wi-Fi. The proposed method is that encapsulate the video stream files become probing packet, in fact, it do not need any additional burden. It has advantage of both active and passive measurement of detection. In this paper, the method used to calculate the bandwidth of self-made, so you can upgrade the client bandwidth detection accuracy. For the easily packet loss of wireless network environment, the methods we adopted, avoid the large amount of error from bandwidth detection due to packet loss, it can improve the accuracy. Our methods are proved to be superior to other bandwidth detection tools in measured results.

並列關鍵字

available bandwidth estimation ； IEEE 802.11

參考文獻

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