Research On P2P Media Transmission Based SIP System And Its Key Techniques

On the rapid development of Internet network and urgent demand to convenient communications, IP communication is put in front of Internet Applications, and it is evolving into EoIP (Everything over IP) communication. Because of the best-effort service, Internet can not assure service quality, which makes IP Communication system have severe QoS problems and hinders its further development. Thus, the research work on QoS problem of IP communication system has great signality.Based on current solutions, and the combination of SIP protocol, P2P network and Application layer routing technology, this paper proposes a SIP+P2P system to solve the QoS problem, in which the SIP signaling is still Client/Server based and the media is transmitted through P2P network. Focusing on the following key issues of SIP+P2P system, such as path negotiation mechanism, path quality evaluation model, overlay model of P2P Relay network, Peer Relay lookup scheme and routing optimization, we propose corresponding solutions.The main research of the dissertation can be summarized as follows:(1) Based on an overview of system architecture of current IP communication systems, a SIP+P2P system is proposed:in which we use centralized SIP signaling and P2P media transmitting, and leverage P2P Application layer routing network to improve quality of media transmitting. In this framework, in order to provide multi-path routing scheme, we extend the SIP signal and design a mechanism of multi-path negotiation and setup; towards the path quality evaluation problem, a path quality prediction model based on network performance is proposed.(2) Towards the P2P Relay overlay model problem in SIP+P2P system, a hybrid P2P overlay model, named Relay Service Cluster Overlay Network (RSCON), is proposed. This model can simulate the tiers and cluster properties of the real internet, and can resolve the overlay model problem of P2P Relay network effectively. Furthermore, towards the current internet's complicated topology, an improved cluster overlay model is proposed, which can be more compatible with complicated Internet topology. The experiments and analyses prove that RSCON and its improved model have good scalability and low relative path quality cost, thus showing that RSCON is similar to the real internet. (3) Based on the RSCON model, a topology-aware Relay lookup scheme is proposed. Different with traditional algorithms, this scheme can explore the topology information effectively. Furthermore, towards the current internet's complicated topology, an improved topology-aware relay lookup scheme based on improved RSCON model is proposed, which can exploit the TIV effectively. The simulation results show that topology-aware Relay lookup scheme has higher hit ratio of best relay and better path quality when compared with other schemes.(4) Finally, based on the multi-path routing mechanism in SIP+P2P system, we propose three routing optimization methods according to three typical application problems:1) a dynamic path-switching method for single media stream; 2) a separated transmitting method for multiple media streams; 3) a parallel and intelligent transmitting method for high bandwidth media stream. The path-switching method can select and switch to the best path according to candidate paths'performance, thus assuring the whole end-to-end path quality. The separated transmitting method selects different paths for each media stream, and switches these paths separately. This method leverages path diversity of internet, and increases the potential bandwidth effectively. The parallel transmitting method can distribute high throughput stream into multi paths, and use intelligent routing algorithm to control packet routing, thus implementing load balance and improving end-to-end bandwidth performance. In this dissertation, we verify these routing optimization methods experimentally. The experiment results show that our routing optimization methods can improve QoS performance of IP communication system significantly.The QoS problem is a key issue in IP communication system. The research of this dissertation is focused on the QoS problem of IP communication system, and proposes a P2P solution for application layer routing mechanism. This research is significant to the development of IP communication industry of our country and the enhancement of competitiveness in technology and standardization of our country.