The Research Of Heterogeneous Multipath Selection For Next Generation Mobile Communication Service

With the rapid development of wireless network technology,the widespread deployment of diversified network devices and the increasingly ubiquitous use of multiple network interfaces in mobile terminals,it is becoming a hot research topic both at home and abroad to make full use of heterogeneous wireless network technology for parallel multipath transmission.Owing to the traditional TCP protocol cannot achieve multipath transmission,the Internet Engineering Task Force(IETF)in 2011 released the Multipath Transmission Protocol(MPTCP),which is compatible with the traditional TCP protocol and the current application,enabling mobile terminal devices to utilize heterogeneous wireless network technologies for transferring data by multipath to maximize network throughput and reduce transmission delays.So,the MPTCP-based parallel transmission will be the future trend of network services.By reading the literatures that are about the technology of parallel multipath transmission and the performance optimization of MPTCP,we can learn: the data transmission of MPTCP is so easy to cause packet loss and disorder that result in the serious problem of cache congestion.The reasons of these problems are as follows:(1)The path switching mechanism cannot reasonably allocate data scheduling problems;(2)The default retransmission mechanism is unable to transmit retransmitted data quickly.To solve the above problems,this paper proposes a multi-attribute aware path switching mechanism(MPTCP-MAPS)that is designed basing on the environment of realistic heterogeneous wireless network.It takes advantage of the multi-attribute perception path estimation model for gaining the values of each path round-trip time(RTT)and packet loss rate(Loss Rate);then using the path switching index algorithm to normalize the performance parameters and calculating the switching index of each path;and the paths are stored in ascending order according to the wireless path switching index;finally the data packet is allocated to the best performance path.By building a simulation scenario in NS2,we analyze and compare the performance of the existing path switching mechanisms and the proposed MPTCP-MAPS mechanism in terms of average throughput and average delay.The results show that MPTCP-MAPS mechanism has better transmission performance.In addition,basing on the standard retransmission mechanism of MPTCP protocol and taking the five retransmission mechanisms in CMT-SCTP as reference,a nov-el MPTCP-based retransmission mechanism(MRTX-CWND)is proposed in this paper.This retransmission mechanism selects the path,which is with the largest cwnd from the available paths of MPTCP,to transmit data.The retransmission packet information collection model firstly collects the retransmission data information of each path;then using the retransmission path selection mechanism for obtaining the cwnd values of other available paths to select the path with the maximum cwnd;and finally the retransmission data is distributed to the path to transmit.By setting up multipath simulation network scenario on NS2,the regular retransmission mechanism,MRTX-CWND and MRTX-SSHRESH retransmission mechanism of MPTCP are compared and analyzed for the performance of average throughput,average delay and jitter.The results show that the proposed MRTX-CWND and MRTX-SSHRESH retransmission mechanisms have better transmission performance,provide better data transmission rate and maintain continuous mobile streaming service to future mobile Internet users.