Research On CCSDS File Delivery Protocol

With the astronautics technology development and space mission operation intermationalization, the design and construction of a unified communications protocol which is to support the nets interoperability between the countries has been more and more imperative. In order to adapt the development of the space data services in our country, to design the high-speed data transmission security protection system onboard spacecraft and to improve the data transfer protocol performance is required, this paper discusses the adaptive file delivery protocol based on the recommendation CCSDS’s file delivery protocol CFDP (CCSD file delivery protocol), and the method proposed in this paper initiatively adapts different link delay, error rate. It also adapts different communication tasks to guarantee the reliability of communication and the timeliness, and finally achieve space information safe and reliable transmission using a large delay, poor safety, reliability of low space linkThis paper mainly focuses on the above problem. Firstly, to support the file transferring in space communication environment, the asynchronous NAK mode of CCSDS File Delivery Protocol is analyzed, and we propose a dynamic adjustment timer algorithm for CFDP in asynchronous NAK mode which is to judge the network condition according to the predicted One-Way delay.Secondly, we analyze the immediate negative acknowledgment (NAK) mode of the Consultative Committee for Space Data Systems (CCSDS) file delivery protocol for the single-hop file transfer operation. We propose an immediate prompt NAK mode for CFDP and timer setting rule that minimizes the expected time taken to transfer a file under the constraint that the throughput efficiency is maximized.We construct the experimental platform with VC 6.0, space links can be simulated by adjusting relevant platform parameters, such as delays and BERs(Bit Error Rate). We implement and validate the dynamic adjustment timer algorithm, and also simulate the immediate asynchronous mode of CFDP in the platform, then we compared the file delivery times of DATA-CFDP, IPNA-CFDP,CFDP and TCP respectively by adjusting relevant platform parameters. Some factors which affect the latency of two mode of CFDP, such as delay, bit error rate, the trigger frequency of external event trigger and so on are analyzed, based on which we obtaine the adaptability of two mode of CFDP in the deep-space communication...