在動態環境中之點對點多媒體串流設計

Abstract

在本文中，我們考慮了在動態環境中點對點多媒體串流的問題，包括檔案提供者的選擇和從檔案提供者中聚集可用頻寬。為了選擇可靠的檔案提供者，我們考慮上載頻寬、存在時間、撥放失敗次數、候選的節點數多寡，提出一個合適的演算法來選擇檔案提供者。此外，由於從單一檔案提供者的上載頻寬，不能滿足一個檔案接收者的串流需求，所以需要從多個檔案提供者來協助下載檔案。為了從檔案提供者中聚集可用頻寬，我們設計一個影像片段配置演算法，以解決單一檔案提供者的頻寬無法滿足播放速率的問題。在我們提出的多媒體串流方法中，撥放時間的延遲和撥放失敗的機率將會進一步的分析來評估效能。由於多數使用者最為關心的是播放品質，所以在本研究中，也分析並檢驗播放時的失敗次數和流暢度。從模擬的結果中，可以看出我們能夠針對多媒體串流提出一個可靠且穩固的方法。尤其是在使用者頻繁進出的系統中，很明顯的，我們提出的方法對檔案接收者更有利。

In this thesis, we consider the problems of peer-to-peer media streaming in highly dynamic environments, including the peer selection and the aggregation of available bandwidth. To select reliable peers, we propose an adaptive peer selection algorithm based on the consideration of uplink bandwidth, life time, playback fault times, and the number of candidates for live broadcasting. In addition, the uplink bandwidth from one single sender cannot supply a streaming request alone so a receiver should download segments from cooperative senders. To aggregate the available bandwidth of multiple senders for streaming, we design a media segments assignment algorithm to resolve this problem. In the proposed media streaming scheme, the time delay of playback and the probability that playback faults happen are analyzed to evaluate the system performance. This study also examines playback pause times and stream quality on traced receivers since users are often concerned with the quality of playback. The simulation results show that our solution is reliable and robust for media streaming. Especially, if the peers join/leave the system frequently during media streaming, the benefits of the proposed schemes are obvious to receivers.