Research On The Key Technologies Of Multipath Transmission Based On IMS Overlay Network

As the next generation network architecture, IP Multimedia Subsystem (IMS) isgradually accepted by international SDOs (Standards Development Organizations).With its access independent feature and unified business model IMS can supportmultiple access network in a unified platform to provide rich multimedia services. IMSis the best solution for FMC (Fixed Mobile Convergence) and Triple Play. The goal ofIMS development is evolution to ALL IP method for the core network and accessnetwork.However, the IP network is a best-effort service network. How to providecarrier-grade QoS on IP network will be the key problem for IMS development. Inorder to solve the problem of quality of service for the IMS network, the internationalSDOs have developed policy-based IMS QoS framework. Access network resourceallocation and admission mechanisms are realized by collaboration of policy decisionand policy execution in the IMS signaling control plane and transport plane. However,the policy-based QoS framework can not solve the problem of link quality loss inaccess network, which makes the QoS decline. In addition, the opinion of centralizedcontrol in IMS network does not give full consideration to the use of network resources,and easily lead to the typical problems a centralized network always has. This paperaims to resolve the QoS problems in IMS by the way of introduction of an overlaynetwork which is compatible with the IMS network QoS framework for applicationlayer transmission optimization in IMS network whith the multipath transmissiontechnology.In this paper, innovative research works are as follows:1. The overlay network construction method is proposed which is compatible withIMS QoS framework. The service related DHT overlay network is built by the overlayservice function. The proposed overlay service function also has the ability ofmeasuring network distance by which the algorithm can speculate the relative networkdistance for candidate service node by BGP attributes. So the topology-aware overlaynetwork for multipath transmission is realized.2. This paper also presents a MDP-based multipath redundant transmissionscheduling algorithm. Concurrent multipath transmission SCTP protocol is improvedto achieve a method of dynamically adjusting the data transmission scheduling policyaccording to the path quality. Redundant transmission of critical data in real-timeservice can avoid single path failure which leads to real-time service quality serious decline.3. A hybrid content distribution mechanism supporting multipath transmission inIMS architecture is proposed. Streaming media service traffic is decentralized by theuse of topology-aware overlay network and traditional CDN to reduce the centralmedia server load and improve network resource utilization and system servicecapacity. Live and on-demand service signaling follow are designed which prove thefeasibility of the method. The mechanism can provide new ideas and methods for IMSstreaming media services.4. A seamless vertical handover method is proposed for IMS heterogeneouswireless networks by multipath concurrent transmission technolog. By drawing on theIEEE802.21media independent handover method combined with multipathconcurrent transmission technology, an IMS vertical handover algorithm forheterogeneous wireless networks is proposed. The algorithm is able to achieve theredundant transmission of data by the way of the multipath transmission technologybefore handover to avoid the issues of data loss and latency in the process of thehandover.Finally, the paper gives signaling processes, algorithm description andimpementation for the above innovation. Several key technologies of multipathtransmission are simulated by simulation tools. The results show that compared totraditional IMS network, the presented multipath transmission based on IMS overlaynetwork in this paper can realize the application layer transmission optimization,effectively improve the utilization of network resources and promote the QoSexperience for service network.