林風臺灣大學：資訊工程學研究所謝丞凱Hsieh, Chen-KaiChen-KaiHsieh2007-11-262018-07-052007-11-262018-07-052007http://ntur.lib.ntu.edu.tw//handle/246246/54135網路電視服務 (IPTV Service)利用寬頻IP網路來提供使用者電視服務。由於頻寬的限制，網路電視服務無法將所有頻道的數位內容廣播給使用者。當一個使用者切換至某一個頻道，而這一個頻道的內容尚未被傳輸至使用者端，此時會產生一段延遲時間，稱為頻道切換延遲時間。此外，當使用者在某一個頻道的數位內容尚未被傳輸到使用者端之前就切換至另一個頻道時，這些數位內容不會被使用者所收看，此種情況被稱之為數位內容遺失。本論文提出了動態頻道預先緩衝機制，稱之為 Dynamic Prebuffering Scheme (DPS)，來減短頻道切換時間及減少數位內容遺失的機率。我們使用了數學及模擬模型來評估動態頻道預先緩衝機制之效能。我們的研究顯示，透過稍微增加頻寬的消耗，DPS可顯著的減短頻道切換時間及減少數位內容遺失的機率。The Internet Protocol TeleVision (IPTV) service utilizes the broadband IP network to provide users TV applications. Due to bandwidth limitation, IPTV does not broadcast the contents of all channels to its users. When a user switches to a channel whose content has not been delivered to the user, a delay called channel zapping time for waiting the content of the switched channel incurs. Furthermore, when the user switches to another channel before the content is received, the content will not be watched by the user, which is referred to as content miss. This paper proposes a Dynamic Prebuffering Scheme (DPS) to reduce the channel zapping time and the content miss probability. Both analytic and simulation models are developed to investigate the performance of the proposed scheme. This study indicates that the DPS can significantly reduce the channel zapping time and the content miss probability by slightly introducing bandwidth consumption.Acknowledgement i Abstract v Contents vii List of Figures ix List of Tables xi 1 Introduction 1 2 The Dynamic Prebuffering Scheme 5 3 Analytic Model 8 3.1 Analysis for the Basic Scheme 11 3.2 Analysis for the DPS 14 4 Performance Evaluation 20 5 Conclusion 28 A Input Parameters 29 B Derivation of Tz,b and Tz,d 31 C Simulation Model 33523046 bytesapplication/pdfen-US頻道切換網路電視群播服務預先緩衝Channel ZappingIPTVMulticast ServicePrebufferthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54135/1/ntu-96-R94922071-1.pdf