Research On Multipath TCP Path Scheduling For Heterogeneous Networks

With The rapid development of communication technology,more and more communication devices are equipped with WiFi,3G,bluetooth,infrared and other interfaces.However,the traditional TCP protocol can only use one path between end systems to transmit data.In order to make full use of the bandwidth resources of the network,IETF(The Internet Engineering Task Force)formally puts forward the MPTCP(Multi-Path TCP),which is the extension of traditional TCP protocol.By using multiple paths to transmit data in parallel and being compatible with TCP,the throughput of the network is improved.However,in the heterogeneous network,the performance of MPTCP decreases as a whole due to the big differences in path delay,packet loss rate,bandwidth and other path characteristics between the network paths,and the use of MPTCP may lead to problems such as the high completion time of short flows and disorder packets at the receiver.Therefore,this paper mainly proposes the scheduling policy of MPTCP in order to mitigate some problems of MPTCP may occur in heterogeneous network.The main work of this paper are as follows: in order to solve the RTO problem caused by MPTCP transmission of short flow,thispaper proposes the MPTCP-SF(MultiPath TCP For Short Flow)algorithm to mitigate the problem of high delay of short flow transmission in the asymmetric heterogeneous network.In this paper,the distribution of object size in the conventional network is analyzed by using the packet capturing tool and the threshold value is determined.Based on the threshold value,the data flow is classified more precisely,and different subflows are selected dynamically for data transmission for different classified data.Compared with the traditional MPTCP scheduling algorithm,the dynamic path scheduling algorithm MPTCP-SF proposed in this paper reduces the completion time of short streams by 42.64% and improves the network throughput of long streams by 11.11%.For the problem of disorder packets at receiver when using multiple paths to transmit data,this paper proposes a scheduling algorithm based on the Data Amount Estimation(DAE),the algorithm comprehensively considers round-trip-time(RTT),congestion window(cwnd),packet loss rate and other indicators of each path,designed the throughput estimation model to estimate transmission capacity of each path at a given time.And then,we use the serial mechanism of MPTCP to allocate different serial number of data packets into different subflows according its transmission capacity,reducing the occurrence of disorder at the receiving buffer and improving the whole throughput of network.