Research On The Key Technologies Of Real-time Streaming Media Transport On Internet

Guaranteeing bandwidth and delay QoS and providing massive multicast delivery capability are the two basic requirements in building media streaming networks. Network layer technologies such as IP QoS and IP multicast have suffered from slow development due to the poor interoperability and expensive cost in deployment. In contrast, application layer solutions represented by content delivery network and overlay multicast have been in the spotlight in recent years and brought about many successful application cases. Network layer transport and application layer overlay transport may complement one another, merging the two transport mode not only help relieve the bottleneck symptoms caused by heterogeneous inter-networks but also achieve the balance between network efficiency and deployment cost.In this paper, we study the key technologies of building media streaming network in heterogeneous Internet by merging overlay transport and network layer transport. Network layer solutions have advantages in efficiency and stability, and application layer solutions win in flexibility and cost. The proposed hybrid transport architecture combines these advantages and helps popularize the real-time streaming application in current Internet. The main research work and conclusions are shown as following:1. We proposed an innovative hybrid network architecture which merges the application layer transporting and network layer transporting in order to guarantee quality of service for real-time streaming media application. In this architecture, the application layer overlay network is logically organized as three layers:source access platform, forward platform and receiver access platform. The bottleneck links are eliminated by reasonable node deployment in three layers. The proposed overlay structure is more flexible and extensible than the'center-edge' structure of content delivery network, and more robust than the pure peer-to-peer structure. By applying proper resource schedule strategies, the proposed overlay network can improve performance on packet loss rate, delay, protocol overhead and system capacity.2. In the proposed architecture, a basic problem is how to meet the QoS requirements of streaming media session. In this paper we research on the bandwidth and delay constraint overlay routing problem. We setup the overlay network model, design a Bandwidth-Delay Constraint Minimum Bottleneck Weighted Routing algorithm and its improvement. Complexity analysis and simulation results show that the proposed overlay routing algorithm can improve the capacity with reasonable overhead.3. When modeling the overlay network, we abstract end-to-end application layer link as virtual link with bandwidth and delay attributes. We further study on the probability characteristics of the virtual link's key attributes, such as available bandwidth, loss rate and delay. We study how to limit the end-to-end packet loss rate, how to implement priority based packet forwarding like Diff-Serv mode. First, we propose that N-TFRC protocol can be used to estimate the end to end link bandwidth such that the overlay flow is fair and friendly to TCP background traffic; second, the two end nodes of a virtual link can use FEC and ARQ to achieve target packet loss rate with minimum bandwidth and delay cost; thirdly, more protection is given to high priority packet by applying priority based packet scheduling during forwarding and lost packet recovering; at last, we evaluate the performance and overhead of the proposed schemes in simulation environment and setup test-bed in local network to evaluate the performance improvement in video and audio streaming transport applications.4. We address the security issues in the proposed network and provide solutions for the three aspects of security risk:session protocol, session data and network infrastructure. Firstly, the HTTP digest authentication and SSL/TLS can be used to secure SIP protocol; secondly, SIP protocol and SDP protocol can be used to negotiate session security association which secures the following streaming media data packets; thirdly, on the network infrastructure security issue, we propose to use access control to cope with routing security risk in IP multicast. We propose PIMac scheme based on PIM-SM multicast routing protocol to implement access control in multicast domain. PIMac uses Rendezvous Point (RP) to collect and update keys. The access control is executed by Designated Router (DR) based on shared key signature authentication algorithm. PIMac implements multicast sender and receiver access control with efficiency and decouples the AAA domain and routing domain. Simulation result shows that it outperforms the existing schemes in protocols overheads.5. In this paper, we also study the cross layer optimization of video streaming transport. We model the end-to-end distortion based video quality as a function of network layer behaviors, and formulate a network-wide optimal routing and rate allocation problem that minimizes the total video distortion. A genetic algorithm based heuristic solution is proposed to solve this optimization problem. In wireless video multicast, in order to cope with heterogeneous receivers, same principles are used to optimize sending bit-rate in the shared wireless link. The evaluation results show that the proposed solutions are efficient and robust enough to adapt the network dynamics; they can provide QoS guarantee for multiple concurrent real-time video streaming, hence improves the overall decoded video quality in clients.This paper includes 62 graphics,8 tables, and 162 references.