Research On Fast File Delivery Technologies In Deep Space

Deep Space Communication is the key technology in the field of deep spaceexploration with significant meaning of economic and military. With the improvementof the complexity about detection task and the need of deep space exploration, theperformance requirement of communication is increasing as well. For the propertiesof deep space communication about large delay, high error rate and intermittentinvisible, it’s important to design a suitable fast file delivery mechanism.This thesis analyzes the characteristics of communication file delivery protocolused in deep space, the current standard of home and abroad, and gives a detaileddiscussion about the performance of deferred NAK and immediate NAK, the twodifferent reliable transmission mechanisms in CFDP. To solve the problem of longdelivery time when the error is high in NAK method, LDPC is proposed to be used inthe communication system. Fountain code is a new field of LDPC study since it’s ableto meet the requirement of reliability for data transmission. It can also be used inCFDP as a no feedback way to decrease the delivery time and improve theperformance. But the fountain coding scheme in latest research has a low utilizationof bandwidth for files of small and medium sizes. To solve this problem, this paperproposes an efficient file delivery protocol using the fountain code over GF(q) to keepthe bandwidth optimization and reduce the transfer delay, which can work with CFDPvery well.Finally, two platforms are built here based on NS3and validation system.Considering the performance of CFDP and the fast file delivery protocol on bothplatform, the result of these simulation proves that under the big transfer delay, thefile delivery protocol using the fountain code over GF(q) have a better performancethan CFDP, and can also save the bandwidth resource when compared with basicfountain encoding method. This method is applicative in deep space communicationsystem.