Research On Path Management And Evaluation Techniques Of Multi-path Transmission Based On Overlay Network

IMS, introduced by 3GPP in Release 5, is a multimedia communication system, which is considered as the main architecture of next generation telecommunication technology. However IMS media transfer mode uses a single path transmission, entirely dependent on bearer network, which causes end to end QoS assurance difficulty, low efficiency and other issues to be a serious constraint of service development. Multi-path transmission for overlay network is considered as a kind of upgrading method of IMS media transmission technology. In order to achieve QoS guarantee in multi-path transmission, both path selection and dynamic load distribution depend on transmission path QoS measurement and evaluation.There is no perfect technical solution of QoS evaluation for overlay network.The current path QoS measurements are for end to end or just a link, which is not applicable to the multipath transmission paths with relay nodes. Although traditional predictive methods can make up for the measurement of hysteresis, multiple sampling will increase a lot of additional burden on the network to ensure recovery without distortion. The current agreements are mainly transport protocols or ICMP protocol, RTCP protocol applies path QoS evaluation to real-time transmission media by statistical analysis of delay, bandwidth and so on, but can not take messaging between relay nodes into account. Combining with the multipath transmission scenario based on application layer relay, this thesis focuses on the following aspects:how to organize and manage overlay network relay nodes and paths, how to measure and predict QoS for the path between relay nodes, how to evaluate end to end transmission path QoS.The main research contents and obtained achievements in the thesis are as follows. Firstly, achieve the overlay network relay nodes and paths organization and management: describe overlay network path and relay nodes classifiedly, and characterize the concept of transmission path stability, which laid foundation for path selection and path QoS evaluation; Secondly, achieve QoS for the path between relay nodes evaluation parameters measurement mechanisms and protocols:on the basis of summarizing path QoS evaluation parameters and its measurement methods, this thesis determines delay, available bandwidth as path QoS evaluation parameters to characterize path, and then design QoS for the path between relay nodes measurement mechanisms and their interactions message format based on relay controller by extending the existing measurement method. Thirdly, achieve the design of path QoS prediction module:to compensate for the lack of active measurement methods, through in-depth study of traditional prediction algorithm, design prediction module primarily based on Compressive Sensing, and the corresponding predictive estimation process. Fourthly, achieve end to end transmission path QoS evaluation:by extending the RTCP protocol, propose Multi Relay Path Sender Report, MRP-SR for short, and Multi Relay Path Reciever Report, MRP-RR for short, which both are new packet type carrying path ID and other parameters. Finally, the results of simulation and test, based on OMNeT++simulation platform, show that the solution proposed in the thesis is universality and accuracy, which can be used in multi-path QoS evaluation based on application layer relay for overlay network.