In consultative committee for space data systems（CCSDS） file delivery protocol（CFDP） recommendation of reliable transmission,there are no detail transmission procedure and delay calculation of prompted negative ac...In consultative committee for space data systems（CCSDS） file delivery protocol（CFDP） recommendation of reliable transmission,there are no detail transmission procedure and delay calculation of prompted negative acknowledge and asynchronous negative acknowledge models.CFDP is designed to provide data and storage management,story and forward,custody transfer and reliable end-to-end delivery over deep space characterized by huge latency,intermittent link,asymmetric bandwidth and big bit error rate（BER）.Four reliable transmission models are analyzed and an expected file-delivery time is calculated with different trans-mission rates,numbers and sizes of packet data units,BERs and frequencies of external events,etc.By comparison of four CFDP models,the requirement of BER for typical missions in deep space is obtained and rules of choosing CFDP models under different uplink state informations are given,which provides references for protocol models selection,utilization and modification.展开更多
A deep space multi-file delivery protocol（DSMDP） based on LT codes is proposed to reduce the influence of long delay and a high bit error rate（BER） in deep space communication. The protocol increases sending redun...A deep space multi-file delivery protocol（DSMDP） based on LT codes is proposed to reduce the influence of long delay and a high bit error rate（BER） in deep space communication. The protocol increases sending redundancy by LT codes to improve the success rate of file delivery, and adopts different protective strategies for different situations of packet loss. At the same time, the multi-file united delivery strategy is adopted to make full use of the retransmission time to reduce the end-toend transmission delay. Furthermore, the protocol determines the quantity of encoded packets according to the feedback for controlling redundancy. The simulation results show that the proposed protocol can significantly reduce the transmission delay of files, which would be effectively suitable for deep space communication environment of high BER and long delay.展开更多
Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in ter...Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in terrestrial communications.Accordingly,the Consultative Committee for Space Data Systems(CCSDS) developed CCSDS File Delivery Protocol(CFDP),which sets standards of efficient file delivery service capable of transferring files to and from mass memory located in the space segment.In CFDP,four optional acknowledge modes are supported to make the communication more reliable.In this paper,we gave a general introduction of typical communication process in CFDP and analysis of its four Negative Acknowledgement(NAK) modes on the respect of file delivery delay and times of retransmission.We found out that despite the shortest file delivery delay,immediate NAK mode suffers from the problem that frequent retransmission may probably lead to network congestion.Thus,we proposed a new mode,the error counter-based NAK mode.By simulation of the case focused on the link between a deep space probe on Mars and a ter-restrial station on Earth,we concluded that error counter-based NAK mode has successfully reduced the retransmission times at negligible cost of certain amount of file delivery delay.展开更多
文件传输协议(File Transfer Protocol,FTP)常常被用于在局域网中传输文件,使用该协议进行文件数据传输,具有传输效率高、可控性强、安全稳定等特点。本文基于FTP协议,提出了一种“微云盘”文件传输与存储系统设计方案,该方案实现了一...文件传输协议(File Transfer Protocol,FTP)常常被用于在局域网中传输文件,使用该协议进行文件数据传输,具有传输效率高、可控性强、安全稳定等特点。本文基于FTP协议,提出了一种“微云盘”文件传输与存储系统设计方案,该方案实现了一种具备FTP系统大部分功能的客户端及服务器系统,将其应用于昆明医科大学校内网络微社区建设,具有传输效率高、安全可靠性好、维护成本低等特点,适用于我校网络育人平台建设。展开更多
This paper deeply discusses the design method of the File Transfer System(FTS)which is based on the File Transfer, Access and Management(FTAM) protocol standard, and probes into the construction principle of the Virtu...This paper deeply discusses the design method of the File Transfer System(FTS)which is based on the File Transfer, Access and Management(FTAM) protocol standard, and probes into the construction principle of the Virtual Filestore(VFS). Finally we introduce the implementation and the key technology of the FTS system.展开更多
The authors, first of all, discuss the importance of implementing application layer protocol ofLAN. A study in this area is required in order to speed up its practical uses as well as further de-velopment in the direc...The authors, first of all, discuss the importance of implementing application layer protocol ofLAN. A study in this area is required in order to speed up its practical uses as well as further de-velopment in the direction. The present paper is a brief report of the authors’ design methodologyand development of File Transfer Access and Management in reference to the ISO / OSI Moduleand implementation of its service protocol in a LAN,展开更多
明确了计算机网络业务可靠性的概念,着重强调了业务不同,可靠性不同.基于网络业务可靠性分层指数的评价法,讨论了局域网FTP(File Transfer Protocol)业务可靠性的试验流程,给出了一种新的测评方法,并对实验室计算机局域网进行了试验测评...明确了计算机网络业务可靠性的概念,着重强调了业务不同,可靠性不同.基于网络业务可靠性分层指数的评价法,讨论了局域网FTP(File Transfer Protocol)业务可靠性的试验流程,给出了一种新的测评方法,并对实验室计算机局域网进行了试验测评.在案例中,针对局域网中的FTP业务可靠性试验中存在的问题,设计了一个基于Windows批处理.bat脚本程序的FTP数据包发生器作为流量生成器,并研究了基于网络嗅探器Sniffer Pro的业务可靠性试验数据收集方法,给出了试验的具体步骤和试验结果.案例中得到的统计数据与实际网络状况相符.由此,该可靠性试验与评估技术得到了实证,同时也为其他业务的可靠性研究提供了参考.展开更多
基金supported by the National Natural Science Fandation of China (6067208960772075)
文摘In consultative committee for space data systems（CCSDS） file delivery protocol（CFDP） recommendation of reliable transmission,there are no detail transmission procedure and delay calculation of prompted negative acknowledge and asynchronous negative acknowledge models.CFDP is designed to provide data and storage management,story and forward,custody transfer and reliable end-to-end delivery over deep space characterized by huge latency,intermittent link,asymmetric bandwidth and big bit error rate（BER）.Four reliable transmission models are analyzed and an expected file-delivery time is calculated with different trans-mission rates,numbers and sizes of packet data units,BERs and frequencies of external events,etc.By comparison of four CFDP models,the requirement of BER for typical missions in deep space is obtained and rules of choosing CFDP models under different uplink state informations are given,which provides references for protocol models selection,utilization and modification.
基金supported by the National Natural Science Foundation of China(61271261)the Natural Science Foundation Project of CQ CSTC(CSTC2012jjA40048)
文摘A deep space multi-file delivery protocol（DSMDP） based on LT codes is proposed to reduce the influence of long delay and a high bit error rate（BER） in deep space communication. The protocol increases sending redundancy by LT codes to improve the success rate of file delivery, and adopts different protective strategies for different situations of packet loss. At the same time, the multi-file united delivery strategy is adopted to make full use of the retransmission time to reduce the end-toend transmission delay. Furthermore, the protocol determines the quantity of encoded packets according to the feedback for controlling redundancy. The simulation results show that the proposed protocol can significantly reduce the transmission delay of files, which would be effectively suitable for deep space communication environment of high BER and long delay.
文摘Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in terrestrial communications.Accordingly,the Consultative Committee for Space Data Systems(CCSDS) developed CCSDS File Delivery Protocol(CFDP),which sets standards of efficient file delivery service capable of transferring files to and from mass memory located in the space segment.In CFDP,four optional acknowledge modes are supported to make the communication more reliable.In this paper,we gave a general introduction of typical communication process in CFDP and analysis of its four Negative Acknowledgement(NAK) modes on the respect of file delivery delay and times of retransmission.We found out that despite the shortest file delivery delay,immediate NAK mode suffers from the problem that frequent retransmission may probably lead to network congestion.Thus,we proposed a new mode,the error counter-based NAK mode.By simulation of the case focused on the link between a deep space probe on Mars and a ter-restrial station on Earth,we concluded that error counter-based NAK mode has successfully reduced the retransmission times at negligible cost of certain amount of file delivery delay.
文摘文件传输协议(File Transfer Protocol,FTP)常常被用于在局域网中传输文件,使用该协议进行文件数据传输,具有传输效率高、可控性强、安全稳定等特点。本文基于FTP协议,提出了一种“微云盘”文件传输与存储系统设计方案,该方案实现了一种具备FTP系统大部分功能的客户端及服务器系统,将其应用于昆明医科大学校内网络微社区建设,具有传输效率高、安全可靠性好、维护成本低等特点,适用于我校网络育人平台建设。
文摘This paper deeply discusses the design method of the File Transfer System(FTS)which is based on the File Transfer, Access and Management(FTAM) protocol standard, and probes into the construction principle of the Virtual Filestore(VFS). Finally we introduce the implementation and the key technology of the FTS system.
文摘The authors, first of all, discuss the importance of implementing application layer protocol ofLAN. A study in this area is required in order to speed up its practical uses as well as further de-velopment in the direction. The present paper is a brief report of the authors’ design methodologyand development of File Transfer Access and Management in reference to the ISO / OSI Moduleand implementation of its service protocol in a LAN,
文摘明确了计算机网络业务可靠性的概念,着重强调了业务不同,可靠性不同.基于网络业务可靠性分层指数的评价法,讨论了局域网FTP(File Transfer Protocol)业务可靠性的试验流程,给出了一种新的测评方法,并对实验室计算机局域网进行了试验测评.在案例中,针对局域网中的FTP业务可靠性试验中存在的问题,设计了一个基于Windows批处理.bat脚本程序的FTP数据包发生器作为流量生成器,并研究了基于网络嗅探器Sniffer Pro的业务可靠性试验数据收集方法,给出了试验的具体步骤和试验结果.案例中得到的统计数据与实际网络状况相符.由此,该可靠性试验与评估技术得到了实证,同时也为其他业务的可靠性研究提供了参考.
