Research On QoE-Oriented Multipath Relay Transmission Control Mechanism

Multipath transmission in overlay network can help to overcome bandwidth bottlenecks and improve the quality of transmission by distributing payload to subflows. It is a developing direction of network transmission technology. Multipath transmission which based on is still in the primary stage, and there is no available scheme at present, especially in the aspect of transmission control mechanism. This thesis mainly studies multipath real-time transmission control mechanism and protocol. Application relay sever forwarding media data in the application layer is a typical overlay network technology based on application layer routing. Actually it reduces the threshold of multipath transmission application.Establishing the multipath transmission environment is only the basis of multipath transmission. Performance and efficiency of multipath transmission depend more on the multipath transmission control mechanism and protocols, especially for real-time transmission. Multiple factors such as business requirements and the dynamic changes of path QoS parameters need to be considered. At the same time, packet sequence needs to be ordered. To meet the demand of QoE, transmission control mechanism needs to balance the relationship between transmission efficiency and reliability. Message of transmission protocol should be concise and efficient.This thesis summarizes the existing multipath transmission protocols combined with the characteristics of relay path and the requirements of real-time transmission. The main contents are as follows:First and foremost, proposed a multi-path transmission control mechanism which based on weight computing, designed two algorithms for multi-path load distribution. According to business characteristics and routes' state, evaluating each path's transmission ability to determine the payload weight distribution ratio. Secondly, designed another multi-path transmission control mechanism which based on service quality feedback, there is a token bucket in the sending end to select the transmission path for payload. And the receiving side sets the "feedback message" mechanism, so the sending end could know the current status of each path and then determine the next token order. Furthermore, the load distribution strategy is adjusted dynamically by feedback messages from the receiving end. Thirdly, a method of sub flow recombination mechanism based on dynamic buffer is proposed and related recombination algorithm is designed. Sub flows are recombined by setting a buffer at the receiving end. By sorting the packets received from sub flows in the buffer, we can mitigate the impact of delay jitter. By monitoring the packet loss rate and delay, we can adjust the length of buffer dynamically.The results of simulation and testing show that the payload distribution algorithm and the multipath transmission control mechanism proposed in the thesis is reasonable and available, which could be used in multipath real-time transmission control.