Design And Implementation Of IMS Terminal With Multipath Relay Transmission Features

Currently,the IMS(IP Multimeidia Subsystem)service model is comparatively mature,but the media transmission adopts the single-path transmission mode which entirely depends on the bearer network.It is difficult to meet the development needs of IMS services due to the disadvantages of the transmission mode,such as difficulty of guarantying end-to-end QoS(Quality of Service),prominent effect of bandwidth bottleneck,low transmission efficiency,et al.which also has seriously hampered the IMS business development.Multipath transmission system based on application layer relay can improve the end-to-end transmission efficiency through the management and utilize of relay paths,building a new mode of transmission.Currently,many businesses have high requirements for real time,but it is difficult to guarantee the end-to-end QoS,and the user's experience is poor,so some business is difficult to get development.The multipath transmission technology can improve the problems in a large degree,and the quality of experience and development of the business will be promoted.A kind of IMS terminal is designed that supports multipath transmission system.Through the expansion of SIP and SDP,the terminal can negotiate session using the server that supports multipath transmission system based on application layer relay.And the terminal can achieve the multipath transmission of media data via the media stack modification,adding load distribution and flow restructuring and other functional modules,and the terminal could negotiate a signaling and transmit media data in multipath.The main research contents and obtained achievements are as follows.1)The function architecture and typical business logic process of the IMS terminal that supports the multipath transmission system are researched and designed.2)A method which could be used to support the transmission media interaction of multimedia service negotiation session is proposed,and the related signaling message flows are designed.3)The media data sending module of IMS terminal is designed,and the dynamic weight adjustment strategy is used to adjust the load of the relay path for improving transfer efficiency.4)The media data receiving module is designed,it can receive data from more than one relay paths and reorganize the data.Finally,the IMS terminal based on the Doubango open source project is implemented.