Research On Coding And Scheduling Technology Of Multipath Transmission In Wireless Networks

Wireless network has evolved a variety of access methods so far,such as cellular network,wireless local area network,etc.Host which has multiple network interfaces and can access a variety of networks at the same time is becoming a development trend.If only a single network interface is used for the transmission of a single service,it will be a waste of resources for the rest of the idle network interfaces.The simultaneous use of multiple path transmission has become one of the research hotspots.This paper studies the existing multipath transmission technology development,and focuses on the transport layer of the multipath transmission protocol.Classical multipath transmission protocol such as SCTP,MPTCP have the problem of queue head blocking,especially in the large difference of multipath quality problems will worsen in the scene.The existence of the problem will affect the upper business especially for low delay tolerate business' s quality of service.As a kind of erasure code,fountain code can solve the problem of queue head blocking well because its data transmission in code block is independent of sequence.In this paper,two kinds of fountain codes LT code and Raptor code are analyzed,and the problems of fountain code in multi-path transmission are analyzed,including block switching,block size adjustment and multi-path scheduling.In addition,a multi-path transmission protocol based on Raptor code is proposed,and the protocol is based on UDP to transmit business data.In order to solve the problem of code block switching,an adaptive code block algorithm is proposed,which dynamically adjusts the size of code block according to the quality of multipath and buffer cache at the receiver end.To solve the problem of multi-path scheduling,a multi-path scheduling algorithm of fountain codes is proposed,which encodes packets through comprehensive scheduling of packet loss rate,time delay and sending rate.TFRC control mechanism is added in the protocol,which provides path quality evaluation data for the protocol by using the feedback channel and partial calculation of the receiver,and the protocol is friendly to TCP.This paper also combines the MPTCP protocol with the multipath transport protocol based on raptor code,and proposes a multi-path transport protocol stack switching scheme.The scheme uses the advantages of two kinds of protocols to different network scenarios.The scheme uses the perception of link quality to switching protocol real-time.In this paper,the protocol stack scheme is designed and implemented in the physical system,and the validity of the multi-path transport protocol is verified by experiment.