An Improved Study on Video over TCP Based on Differential-Priority

• Main Authors: Chia-Hua Lan, 藍家驊
• Other Authors: Wen-Ping Lai
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/337y24

碩士 === 元智大學 === 通訊工程學系 === 104 === Nowadays the popularity of the Internet and the pervasion of Web-based applications have caused the domination of TCP-transport-protocol-based video streaming unicast/multicast and interactive communications. Since video streaming applications is more suitable to the UDP transport protocol in essence, it is necessary to re-evaluate the impacts of the feature difference of TCP (such as error detection and congestion control) on video transmission quality: (1) the unexpected delays of TCP-based video streaming during congestions from TCP’s retransmission mechanism; (2) the effect of TCP’s flow control with the congestion changes. This thesis proposes an improved design on video over TCP based on differential priority, including two design principles: (1) Video packets of different coding importance are assigned with different congestion window adjustment rates: a larger increasing rate is assigned to a video packet of higher importance during low congestion and a smaller decreasing rate to a video packet of less importance during heavy congestion. (2) Cancel the sending of low-importance video packets in a prioritized manner as the congestion level increases. Our simulation results show that the proposed design outperforms the existing ones in achieving better transmission quality, in particular from medium to heavy congestions.