Research On The Techniques Of Concurrent Multipath Transfer In Heterogeneous Networks

With the rapid development of ubiquitous networks from level interconnection to level cooperation, the heterogeneity for different networks and multi-access characters for multi-interface terminals provide the basis and conditions for the concurrent multipath transfer by multiple access methods in the network overlapped areas. Concurrent multipath transfer system can improve the utilization of network resource effectively and enhance capacity of transmit rate and load balancing by aggregating multi-access transmission performance. In addition, using a single interface is often insufficient to meet the requirements of popular, especially for bandwidth intensive services. In order to make full use of a wide variety of surrounding user devices, and further to provide users with real-time, high efficiency and high quality services, it has become a necessary demand for a variety of terminals to work together and jointly provide services.In this dissertation, the packet reordering in concurrent multipath transfer of heterogeneous networks, the fairness of network resource allocation, congestion control mechanisms and concurrent muti-streaming transfer system based on multi-terminals cooperation are discussed. In addition, the architecture and optimization algorithms of concurrent multipath transfer based on virtual terminal are proposed. Furthermore, an analysis model for packet reordering and a multi-user multi-terminal multipath transmission optimization model are also studied in order to optimize the system performance. The concrete contents of this dissertation are given in details as follows:1. In order to analyze the fundamental behavior and influencing factors of packet reordering, several sets of simulation-based multipath experiments are conducted with different aggregating paths. In addition, the relationship between reordering and number of paths is discussed. Furthermore, an end-to-end measurement study of packet reordering in concurrent multipath transfer is presented. To simply the analysis process, a cumulative distribution function of transmission delay for each packet is used. The model is proved to be an effective one by contrastive analysis. What’s more, some solutions to handle it are provided with a further discussion. Finally, based on the model an optimal throughput optimization analysis model for concurrent multipath transfer is proposed by minimizing the reordering time in the receiver. 2. To resolve the fairness problem of bottleneck links in concurrent multipath transfer system, the design principle of congestion control as well as the characteristic and fairness for concurrent multipath transfer is analyzed. In the meanwhile, an overview of the existing multipath congestion control methods is summarized and some open research problems are also stated. According to the characteristics of multi-user multi-terminal multi-path transmission, a transmission control model is proposed based on the network utility optimization. Furthermore, a distributed algorithm for solving the optimization problem is designed, and the stability of the system is verified.3. In order to solve the resource and capacity insufficient in a single terminal, a multi-terminal based collaborative virtual terminal system is proposed. Collaborating with multiple devices in their surroundings and aggregating capacities adaptively is an effective way to improve the user’s experience. The problem of traffic flow assignment in this collaborating system is studied and the architecture for the virtual terminal system is also proposed. Based on queuing theory, the system model is analyzed by the optimization algorithm with the overall system delay and packet loss rate as the performance evaluation. The performance results demonstrate that this system can effectively improve the transmission performance of different types of applications, thus meeting the user’s quality of experience.4. According to theoretical research, a key technology verification and demonstration platform for multi-terminal cooperation and concurrent multi-stream transfer is proposed. In this platform, the heterogeneous network convergence, Wi-Fi based independent service discovery and application layer concurrent multi-stream transmission control method are studied respectively. Through an analysis of typical application scenarios, this dissertation provides some viable solutions for the expanding and applying of related technology. What’s more, this platform can also verify the typical key technologies and give some performance evaluations.In conclusion, all the research work in this dissertation lays an import foundation for the modeling architecture, protocol design and practical applying of muti-terminal cooperation and concurrent multipath transfer in the heterogeneous networks environment, and provides theoretical support for the implement of intelligence application in ubiquitous networks.