Design And Implementation Of Concurrent Multipath Transfer Algorithm

With the rapid development of Internet, mobile Internet and related technologies, the inherent defects of TCP and UDP is becoming more and more apparent, such as single path, whole data delay larger, vulnerable to the network attack, as well as the head of data stream block. Thus SCTP is proposed naturally, in the near future SCTP alternative to TCP become transport protocol in the next generation Internet has been paid highly attention and reached a consensus. To aggregate bandwidth, improve transmission throughput of end-to-end, Based on the SCTP some researchers had been proposed Concurrent Multipath Transfer (CMT) solution, namely SCTP-CMT. SCTP-CMT inherited many advantages of the SCTP protocol but because of the differences among paths, the problem of receiving buffer congestion will be relatively serious. Therefore, in order to improve the transmission performance, the search on strategy of concurrent multipath transfer has important theoretical significance and application value.Firstly, this thesis makes a thorough analysis of the advantages and disadvantages for several transmission strategies. Summarize two points which needed to improve:the first one is short of estimation of transmission performance dynamically in the transmission strategy. The second one is that because of the purpose of concurrent transfer is to fully use the network source, but the adoption of partial paths transfer doesn’t make full use of the advantage of multipath transfer. In response to these problems, this thesis proposes the strategy that Quality evaluation Maximize Parallel in CMT (CMT-QMP).The first step is to compute the path quality evaluation parameter Q in order to evaluate the path transmission quality comprehensively. This parameter not only realizes the real-time monitoring of path transmission quality, but also provides the evidence for the transmission strategy carried out. The purpose of the thesis is to adopt effective algorithm to reduce the differences of different paths and realize the biggest parallelization in concurrent multipath transfer, in the part of transmission strategy, use the path quality evaluation parameter to classify the transmission path, the method of classification is the comparison of weights inequality. After classification in the same collection decrease the difference of paths and in the different collections use the average of path quality evaluation parameter and the numbers of paths to allocate data. In the same collection, because of the difference of paths decreased, use the method of Round Robin to allocate data in order to improve the transmission efficiency.Through the simulation experiment, from the comparison of four transmission algorithms, the CMT-QMP algorithm can solve the problem of receiver buffer blocking effectively. Simulation results show feasibility and effectiveness of the algorithm. Finally, the thesis gives the summary of the subject and proposes the next research direction.