パケットネットワークにおけるストリーミングメディアに対するパケット損失補償技術に関する研究

摘要

Media streaming over packet networks such as the Internet are increasingly becomingpopular with the development of the broadband networks. These streaming media require ahigher quality of service (QoS) compared to non real time media such as E-mail The mainfactor that degrades the QoS of streaming media is packet losses, and Forward Error Correction(FEC) is promising technique to recover them and improve QoS of streaming media. Therefore,the general objective of this dissertation is to provide packet loss recovery techniques based onFEC over packet networks in order to improve the QoS of streaming media.Streaming media can be categorized into live and on-demand types. First, an efficient FECmatrix structure is proposed to recover bursty packet losses for live streaming media. Theproposed matrix structure combines different FEC matrices with the small matrix size andchanges the loss-recovery ability dynamically according to the network congestion withoutdeterioration of the data transmission efficiency. It can improve both packet loss ratio and datatransmission efficiency compared to conventional FEC methods. Performance of the proposedmethod is evaluated and compared to the conventional methods.Second, the issues of adverse effects of FEC overheads are addressed and analyzed. Theresults show FEC overheads degrade QoS of streaming media with increase of the number ofstreaming sessions. In order to solve this problem, a novel packet loss recovery techniquesuitable for on-demand streaming media is proposed. It separates the FEC packets from theoriginal media packets and creates the FEC content consisting of the FEC packets. Then, itsends the FEC content to the receiver end using TCP before media streaming starts. Thus, thismethod can minimize the adverse effects of FEC overheads and can efficiently recover packetlosses for on-demand streaming media. Performance of the proposed method is evaluated andcompared to the conventional methods.Finally, distributed routing architecture to maintain streaming media quality is proposed torecover big bursty losses. Generally, when network failures or heavily congestions occur, reroutingis done in a network domain to cope with them. However, re-routing always causepacket losses and highly degrades QoS of streaming media. These losses are big bursty andtherefore, even the FEC matrix structure cannot recover them. In order to solve this, theproposed method distributes media and FEC packets among some transmission routes.Therefore, it can recover the big busty losses due to re-routing and provide network architecturewith no service outage for streaming media. Performance of the proposed method is evaluatedand compared to the conventional methods.