Video Conferencing System Based On SDN-enabled Layered Multicast

In recent years,with the continuous development of Internet communication technology,the researches and applications of the video conferencing system have gradually changed the traditional conference mode and brought profound changes to the human social life.The current multi-point video conferencing system is bridged by a device called multipoint control unit(MCU),which may cause a large consumption of network resources when the users increase,making the quality of video service difficult to guarantee.However,related researches of Scalable Video Coding(SVC)and Software Defined Network(SDN)provide new solutions for the dilemma of traditional video conferencing systems.Scalable video coding technology uses hierarchical coding and selective transmission as the main means to achieve scalability.The same video source can be encoded to different frame rate,resolution and quality levels for different channels and terminals to reduce the transmission cost.In order to optimize the network flow management,the new model of software-defined network separates the control plane of the traditional network equipment from data plane to make more effective use of network resources.In this thesis,a new video conferencing system architecture based on SDN-enabled layered multicast and correspondent multicast algorithms are proposed for the basic needs of video conference.The main work is as follows:Firstly,the realization principle of the system is expounded in detail.The overall structure of the system and the specific functions of each module are also designed and explained.Through the scalable video coding,the system implements layered multicast stream to satisfy conference users with different device capability.The SDN controller is responsible for monitoring network status and adjusting the layers of video stream dynamically.A conference manager is also designed to facilitate the conference management,which discards traditional Internet Group Management Protocol(IGMP)and professional equipment like MCU.Secondly,a layered multicast algorithm and corresponding dynamic adjustment algorithm are designed to realize the architecture.The appropriate path will be selected for each layer of the video according to the link information and video bit rate to maximize the usage of network bandwidth resources and improve the service quality to meet the dynamic QoS requirements of users.Finally,a large-scale simulation experiment is carried out in order to test the algorithm performance.A simple prototype system is also built for system function verification and network adaptive test.Experimental results show that the system can not only provide a flexible and controllable layered video multicast service but also reduce the network resource usage while guaranteeing the quality of a video conference.