File Delivery Protocol Based On Fountain Code In Deep Space Communication

Deep space exploration is one of the most important part of humanspaceflight activities. In deep space missions, communication system should beresponsible for the remote command, returnning probe data and other criticaltasks. The fact deep space environment is greatly different from the terrestrialenvironment, makes the traditional file transfer protocol in deep space meeting agreat challenge.For the features of deep space communication, this paper introduced theCFDP file transfer protocol, elaborated CFDP five transmission control modeand made a summary of the characteristics of CFDP File Transfer Protocol. Thispaper also analyzed the file transfer delay of CFDP protocol. According to thesimulation results, this paper analyzed the advantages of CFDP, compared to thetraditional FTP protocol and limitations of CFDP protocol in deep spaceenvironment. The increace of bit error rate in deep space channel result in thatthe CFDP protocol requires multiple retransmissions to complete file transfers.This makes the file transfer delay increasing greatly.In recent years, the fountain code as a forward error correction technologyis introduced into deep space communications. Because it has the ability toapproach Shannon limit in any probability, the caracteristics of no fixed rate andno feedback. This paper proposed a FFDP File Transfer Protocol based onfountain codes and gave the FFDP frame structure and system architecture. Thispaper also described the workflow of FFDP protocol including theacknowledgment mode and no acknowledgment mode. Meanwhile, this paperanalyzed the file transfer overhead and latency of FFDP file transfer protocol.From the simulation results, we know that as the one-way transmissiondelay is small, CFDP protocol performs better than FFDP protocol, as theone-way transmission delay increases, FFDP protocol performs better than CFDPprotocol. When the one-way transmission delay is small, the amount of data hasbeen sent determines the total file transfer delay, when the one-way transmissiondelay is large, the number of interactions in the entire transmission processdetermines the file transfer delay. When one-way transmission delay is large, theFFDP protocol reduce the overall transmission protocol interaction times toobtain a better performance. It is suitable for deep space communication.