Research On Multipath Transmission Mechanisms In Software Defined Networks

With the rapid development of network communication technologies,network traffic and the number of terminals are increasing explosively.These will bring great pressure and challenges to the data transmission services.In addition,the exclusiveness and closure property of current network architecture leads to cumbersome and inefficient network configuration.These disadvantages are difficult to realize the intelligent control and dynamic adaptation.Many researchers focus on the study of future network architecture and protocols in recent years.Software Defined Network(SDN),as one of the future networks,can guarantee the management and control of data transmission which supports the dynamic adaptation of network resources flexibly due to the design feature of"separation of control and forwarding".What's more,Multipath TCP(MPTCP)can improve the throughput through establishing multiple paths by taking advantage of multiple interfaces.Therefore,deploying the multipath transmission protocol in SDN will improve the transmission performance.However,how to achieve high-quality multipath data transmission service in SDN still faces a series of challenges:(1)The current path management of MPTCP is relatively blind and inefficient,and there is a lack of cooperation between the endpoint side and the network side.(2)Most researchers only devote themselves to improve the transmission performance,neglecting the price cost which is another factor that users are concerned about.It is difficult to provide efficient and low-cost data transmission service.(3)Current multipath handover methods are hysteretic which can not compensate the declining throughput proactively.(4)Current optimization solutions of MPTCP focus on traditional transmission performance,none of these works considers the freshness metric for real-time network applications to satisfy the real-time demands.To deal with the above challenges,this Ph.D.thesis studies the multipath transmission mechanisms in software defined network,and mainly focuses on path management,data scheduling,mobile handover and congestion control.The contributions are summarized as follows:(1)A novel QoS-driven and SDN-assisted MPTCP path selection approach is proposed.The approach constructs a new network architecture with joint optimization of "network side and endpoint side".This architecture contains three modules:Topology collection and path calculation module,Number of subflows optimization module and Path allocation module.Through the cooperation of the above three modules,the throughput can be effectively improved.(2)A novel stochastic optimal scheduler for MPTCP is presented.Through utilizing Lyapunov optimization technique,this scheduler analyzes and solves the trade-off problem between the performance and price cost from users' perspective.This scheduler makes corresponding control decisions.Besides,with the help of centralized control in SDN architecture,the network side can feed the status information of each path back to endpoint side for making decisions.The scheduler can achieve the trade-off between the performance and price cost intelligently.(3)A novel game-enhanced compensation handover scheme for MPTCP is proposed.A fluid-based multipath compensation handover method is designed,which can maintain the throughput at a steady state during handover.In addition,a game-based optimal candidate RSU selection mechanism is proposed,which selects the RSUs with the best transmission quality for the handover decisions and feeds this decisions back to the endpoint side.This handover scheme can make the handover process smooth and transparent.(4)A novel age of information-aware congestion control algorithm for MPTCP is presented.This algorithm constructs a new four-tuples multipath transmission model to describe the transmission state in the SDN architecture.Then we design an age of information evaluation method.In addition,we propose an innovative age-assisted fluid model of MPTCP congestion control,which introduces the optimization target of data freshness in order to satisfy the demand of real-time network applications.In summary,this thesis focuses on the key technologies of multipath transmission by taking advantage of SDN technology.Through constructing a new network architecture with joint optimization of"network side and endpoint side",SDN technology and MPTCP are organically combined,which has certain theoretical novelty and application value.The research achievements of this study can benefit our nation's design and optimization of the next generation network architecture,data transmission services to some extent.