| With the continuous development and innovation of communication and network technology,the types of terminal network access have made great progress in diversity and speed.WIFI,3Q4G and so on have been widely deployed so as to build a heterogeneous network consists of multiple networks.The rapid development of Internet business is far beyond our expectations,especially multimedia business and file service,which put forward higher demands on network bandwidth,and as a result the bandwidth of a single network connection can not meet the needs of users.In order to improve the utilization rate of network resources and make full use of the bandwidth of networks in heterogeneous environment,multipath transmission technologies become a hot spot to solve this problem.Among them,the MPTCP multipath technology has obtained rapid development and preliminary application in recent years because of its unique advantages and good prospects.But MPTCP technology is not mature at present stage,the scheduling policy about how to make reasonable distribution has become the bottleneck of MPCTP.Therefore,MPTCP data scheduling strategy becomes the key technology of MPTCP multipath transmission.Existing data scheduling strategies of MPTCP are Round Robin and Lowest-RTT.Round Robin is a stateless and static data scheduling strategy,regardless of transmission condition differences of each link in heterogeneous network,which reduces its efficiency.Lowest-RTT is a kind of dynamic data scheduling strategy,but it only considers RTT(round trip transfer time)of path,doesn’t make full use of the bandwidths of other paths whose RTT are relatively a little bigger,as a result can’t attain the anticipated goal in some cases.In order to make up for the defect of existing data scheduling strategies,this paper proposes MPTCP scheduling strategies based on dynamic data scheduling,fully considering the complexity of heterogeneous network in the realistic environment and the rapid change of the transmission quality of each link.First of all,in order to make up for the defect of Lowest-RTT strategy,we consider the adaptability of data scheduling and congestion control,and then put forward a data scheduling strategy based on path transmission capacity estimation.This strategy avoids the data transmission producing periodic window in half because of congestion packet loss,improves the effectiveness and stability of data transmission in a long time.Secondly,according to the RTT rate of change,we build a congestion factor and one link data distribution model,then put forward a data scheduling strategy based on time delay change and load balancing.This strategy gives full consideration to the change of congestion of each path and bandwidth utilization.Finally,this paper sets up a simulation environment based on NS3 MPTCP,and makes simulation between the proposed scheduling schemes and existing Lowest-RTT scheduling module.Analysis shows that the two proposed MPTCP scheduling strategies based on dynamic data scheduling have a certain advantage in efficiency of data transmission,and improve quality of network transmission. |
