Research On The Key Technologies Of Efficient Streaming Distribution In The Mobile Internet Environment

Mobile Intnenet is the combination of mobile networks and Internet services; it expects to use the all-IP network structure to integrate cellular mobile communication system with broadband generalized radio access network and traditional Internet, and to provide abundant Internet services to mobile users through heterogenerous networks. With the fast development of wireless access technologies and streaming services during the past few years, more and more mobile users hope to enjoy streaming services anytime anywhere. This has highly promoted the boom of mobile streaming technology, which has become the focus of attention of the industry and academia circles. However, the large scale of mobie users, the mobility of terminal and the heterogeneity of access networks have brought huge challenges to the design of mobile streaming systems and mobile streaming delivery technologies, while the existing solutions cannot cope with these challenges. Hence, how to efficiently distribute streaming in mobile Internet is a problem worth in-depth study, and it has great meaning for the construction of large-scale mobile streaming system and the improvement of its service performance.The main object of this paper is to design a mobile streaming delivery architecture in the heterogeneous mobile Internet environment, and to achieve efficient delivery in this architecture. For this purpose, two problems need to be considered. Firstly, how to support heterogeneous mobile users connected through heterogeneous access networks, while ensuring high quality of streaming delivery from hardware level? Secondly, how to settle the problem of user expierenence decreasing caused by user mobility and heterogeneity of access networks and terminals, while ensuring high quality of streaming services from software level?Facing these two problems, this dissertation makes efforts and contributions in the following aspects.(1) We propose a mobile streaming delivery architecture within the heterogeneous integration environment. This architecture combines IP Multimedia Subsystem (IMS) and Content Delivery Network (CDN) and leverages their advantages to support heterogeneous networks and terminals, and meet the high quality requirement of streaming services.(2) We propose a client-driven QoS-oriented server selection scheme to solve the problem of service quality decrease caused by user mobility. This scheme allows mobile terminals to forwardly detect service quality and then select the best edge server according to comprehensive quality metircs. It also leverages distributed mapping scheme to reduce the pressure of mapping system and makes it more scalable.(3) We propose a content placement scheme to optimize the delay performance of mobile VoD services. This scheme builds the content placement problem into a mixed interger programming model, uses the Lagrangian rlaxation to simplify the model and then utilizes the heuristic sub-gradient optimization algorithm to solve the model. This scheme takes user mobility into consideration from both spacial dimension and temporal dimension and guarantees the optimization of delay performance from an overall perspective.(4) We propose an overlay multicast scheme to improve the delay performance of mobile live streaming services. This scheme considers adding live transcode functions to overlay nodes, and then construsting minimum-delay multicast tree according to different code rate requirements of different mobile terminals. This scheme will be able to meet the quality needs of different temnials and reduce the end-to-end delay while ensuring the server-side resourcing consumption is within its capacity.