OFDMA系統下之隨選品質可調性視訊群播機制; Quality on Demand SVC-Based Traffic Multicast Scheduling on OFDMA System

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題名:	OFDMA系統下之隨選品質可調性視訊群播機制;Quality on Demand SVC-Based Traffic Multicast Scheduling on OFDMA System
作者:	廖薏萍;Yi-Ping Liao
貢獻者:	通訊工程研究所
關鍵詞:	可調性視訊編碼;視訊群播;OFDMA;SVC;Video multicast
日期:	2011-01-15
上傳時間:	2011-06-04 16:07:03 (UTC+8)
出版者:	國立中央大學
摘要:	隨著無線網路技術的發展，及網路服務使用者人數的增加，視訊網路服務的需求愈來愈多，使用者對於視訊品質的要求也逐漸提升。因此近年來，IPTV服務和現場轉播節目愈來愈受歡迎，對於高品質視訊影像服務的需求，導致高傳輸效能的無線網路環境需求也相對的提高。這些網路服務均具有高頻寬需求及低延遲的限制。因此在頻寬資源有限的狀況下，視訊影像群播機制提供有效率的提供視訊影像服務給一群使用者。另一方面，無線網路環境下的通道狀況較不如有線網路穩定，合適的頻譜資源分配方式即成為重要的議題之一。本論文是架構在WiMAX 無線網路環之下，採用OFDMA技術來提供頻譜資源分配的彈性。視訊串流採用可調性視訊編碼(scalable video coding, SVC)將視訊串流編碼成一層base layer 及多層enhancement layers來提供影像傳送的彈性。除此之外，本系統使用forward error correction (FEC) 技術來修正影像資料傳送時的錯誤及保證視訊影像品質。本論文所提出的群播群組分配機制可將於同一視訊影像群播服務下的使用者切割成多個傳送群組，並根據各傳送群組的通道狀況和影像品質需來傳送視訊影像資料。另一方面，調整所使用的MCS (modulation and coding scheme)及視訊階層(video layers)的數量之機制，並配合FEC來達成最大傳輸效率的目標。系統根據使用者的通道狀況動態調整所使用的MCS，並計算所需的FEC冗餘數量和傳送的視訊階層數量。從模擬的結果可以看出我們所提出的頻譜資源分配機制能達到較高的傳送效率，且能減少頻譜資源的消耗。 With the development of wireless network technology and the rapid growth of users, more and more real-time video network services have been highly demanded. For example, the IPTV service and live program broadcast become more popular recently. The demand of high quality video services leads to the requirement of high performance wireless transport networks. The radio resource shall be arranged properly to meet the needs of above real time services. The delivery of video traffic through multicast is an effective way to achieve efficient radio resource utilization in wireless environment. As the radio condition is not as stable as the fixed lines, a good radio resource allocation scheme is one of the main issues to accomplish the above objective. The WiMAX network adopts the OFDMA technology to provide effective bandwidth allocation and high resource utilization of radio spectrum. Those features can provide the flexible resource arrangement for services with layered traffic. The video encoding technology, scalable video coding (SVC), is utilized to achieve high scalability of video transmission in the environment with changeable channel quality. This thesis studies the effective radio resource allocation of SVC traffic multicast for users with different quality requirements in OFDMA system. In addition, in order to correct possible errors occurring in such environment and ensure video quality, forward error correction (FEC) technology is incorporated with our proposed scheme for effective radio resource utilization. The proposed scheme divides a service multicast group into several delivery multicast groups according to channel conditions and quality requirements. The proposed MCS selection with FEC and video layers allocation mechanism aims to maximize the transmission efficiency with the adjustment of selected MCS for multicast transmission, number of video layers and size of FEC redundancies. It raises selected modulation and coding scheme (MCS) for transmission with the size of FEC redundancy, and allocates suitable number of SVC layers. The simulation results show that the proposed scheme can acquire high transmission efficiency and reduced the spectrum resource consumption.
顯示於類別:	[通訊工程研究所] 博碩士論文

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