Investigation On Control Mechanisms Of Video Stream Media QoS In Next Generation Network

With the development of Next Generation Network (NGN) and the widely application of broadband technology, a lot of multimedia information and real time application in Internet steadily increase. The NGN is becoming an integrated service network for multimedia, such as data, voice, image and real application etc, and especially the strong visual impression of video stream media application becomes one of the most important applications for people to enter the broadband network. NGN is required to provide good QoS support for these demonds. IP network which carries the NGN traffic, guarantees the QoS of IP network, will effectively ensure the QoS of NGN. However, traditional IP network can only provide "Best Effort" service and can't satisfy different network traffic quality requirements of multimedia applications or every kind of users. The video stream media QoS control mechanisms in NGN have become one of the research hotspots on networks in recent years.This thesis firstly analyses the development of video stream media and the QoS actuality of IP network which carries the traffic of NGN, and then points out the problems which should be solved in order to guarantee the QoS of IP network if the IP network serves as to the NGN. Two kinds of service models of QoS: IntServ and DiffServ which are defined by IETF, are discussed. Moreover, SLA (Service Level Agreement) for different level service is briefly introduced.Secondly, this thesis analyses the relating techniques of video stream media and introduces several video compression coding standards. MPEF-4 is chosen as the video compression coding standard of the investigation target for this thesis based on the comparison among many facets.Thirdly, this thesis studies the system structure of DiffServ model, analyses the functions of core router and edge router in DiffServ model, and investigates the control mechanisms of IP QoS in DiffServ, including the packet marking policies, the queue scheduling algorithms and the congested packet dropping mechanisms.Finally, based on the studies in the previous parts, this thesis analyzes the characteristics of MPEG-4 video frames;brings forward the QoS control mechanisms in the IP network which serves as the carrier of NGN;adds the PRI QoS control mechanisms into the frames of video stream in congested network based on DiffServ model;and uses SLA to implement different level of services for different request of QoS. The control mechanisms of viedo stream media QoS in NGN are simulated and evaluated by NS2.