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
文章深入研究物联网中的窄带物联网(Narrow Band Internet of Things,NB-IoT)技术,重点探讨基于省电模式(Power Saving Mode,PSM)机制的优化方法,分析NB-IoT的数学原理,研究一种基于PSM机制的动态调整算法,并利用MATLAB平台上的Simulin...文章深入研究物联网中的窄带物联网(Narrow Band Internet of Things,NB-IoT)技术,重点探讨基于省电模式(Power Saving Mode,PSM)机制的优化方法,分析NB-IoT的数学原理,研究一种基于PSM机制的动态调整算法,并利用MATLAB平台上的Simulink工具进行仿真实验。实验结果显示,相比传统方法,文章方法能显著降低平均功耗,在实际应用中具有有效性和稳定性。展开更多
与传统的基于内核的报文处理方式相比,数据平面开发套件(Data Plane Development Kit,DPDK)技术大幅度提高了数据处理的效率。目前,DPDK只提供了简单的以太网收发包的工作,无法直接处理OSI模型4层以上协议的数据。根据DPDK技术特点设计...与传统的基于内核的报文处理方式相比,数据平面开发套件(Data Plane Development Kit,DPDK)技术大幅度提高了数据处理的效率。目前,DPDK只提供了简单的以太网收发包的工作,无法直接处理OSI模型4层以上协议的数据。根据DPDK技术特点设计和实现了一种基于DPDK的用户态协议栈。实验结果表明,与传统的内核协议栈相比,该协议栈转发TCP和UDP数据包效率提升了20%左右。展开更多
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.
文摘文章深入研究物联网中的窄带物联网(Narrow Band Internet of Things,NB-IoT)技术,重点探讨基于省电模式(Power Saving Mode,PSM)机制的优化方法,分析NB-IoT的数学原理,研究一种基于PSM机制的动态调整算法,并利用MATLAB平台上的Simulink工具进行仿真实验。实验结果显示,相比传统方法,文章方法能显著降低平均功耗,在实际应用中具有有效性和稳定性。
文摘与传统的基于内核的报文处理方式相比,数据平面开发套件(Data Plane Development Kit,DPDK)技术大幅度提高了数据处理的效率。目前,DPDK只提供了简单的以太网收发包的工作,无法直接处理OSI模型4层以上协议的数据。根据DPDK技术特点设计和实现了一种基于DPDK的用户态协议栈。实验结果表明,与传统的内核协议栈相比,该协议栈转发TCP和UDP数据包效率提升了20%左右。
基金Supported by the National Natural Science Foundation of China under Grant No.60025205 (国家自然科学基金) the National Grand Fundamental Research 973 Program of China under Grant No.G1999035802 (国家重点基础研究发展规划(973))
