The architecture and protocols of Internet can't work well in space environments. To form a reliable and safe space network, characteristics of space communication network one discusse, brief synthesis is performe...The architecture and protocols of Internet can't work well in space environments. To form a reliable and safe space network, characteristics of space communication network one discusse, brief synthesis is performed for consultative committee for space data system (CCSDS) space communications protocol standards (SCPS), and a model accounting for data security problem of space-earth integrated network is provided.展开更多
The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport P...The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport Protocol (DR-TCP) for point-to-point communication in deep space exploration missions. The issues related to deep space communication protocol design and the areas where modifications are necessary are investigated, and a protocol is designed that can provide good throughput to the applications using a deep space link. The proposed protocol uses a cross layer based approach to find the allocated bandwidth and avoids initial bandwidth estimation. A novel timeout algorithm estimates the timeout duration with an objective to maximize throughput and avoid spurious timeout events. The protocol is evaluated through extensive simulations in ns2 considering high RTT values typically seen in Lunar and Mars Exploration Networks under different conditions of packet error rates. DR-TCP provides a significant increase in the throughput as compared to traditional transport protocols under the same conditions. A novel adaptive redundant retransmission algorithm is also presented to take care of the high PER in deep space links. The effect of the Retransmission Frequency has been critically analyzed considering both Lunar and Deep Space scenarios under different levels of PER. The results are very encouraging even in high error conditions. The protocol exhibits a RTT independent behavior in throughput, which is the most desirable quality of a protocol for deep space communication.展开更多
This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). ...This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). The primer focus is the telecommand (TC) part of the standard. The implementation of the standard was in the form of DLL functions using C++ programming language. The second objective of this paper was to use the DLL functions with OMNeT++ simulating environment to create a simulator in order to analyze the mean end-to-end Packet Delay, maximum achievable application layer throughput for a given fixed link capacity and normalized protocol overhead, defined as the total number of bytes transmitted on the link in a given period of time (e.g. per second) divided by the number of bytes of application data received at the application layer model data sink. In addition, the DLL was also integrated with Ground Support Equipment Operating System (GSEOS), a software system for space instruments and small spacecrafts especially suited for low budget missions. The SDLP is designed for rapid test system design and high flexibility for changing telemetry and command requirements. GSEOS can be seamlessly moved from EM/FM development (bench testing) to flight operations. It features the Python programming language as a configuration/scripting tool and can easily be extended to accommodate custom hardware interfaces. This paper also shows the results of the simulations and its analysis.展开更多
Deep space communications has played an important role in deep space exploration. Compared with common satellite and terrestrial communications, deep space communications faces more challenging environment. The paper ...Deep space communications has played an important role in deep space exploration. Compared with common satellite and terrestrial communications, deep space communications faces more challenging environment. The paper investigated the unique features of deep space communica-tions in detail, discussed the key technologies and its development trends for deep space communica-tions.展开更多
Specification language is used to provide enough information for the model of the cryptographic protocol. This paper first extends strand space model to dynamic strand model, and then a formal specification language f...Specification language is used to provide enough information for the model of the cryptographic protocol. This paper first extends strand space model to dynamic strand model, and then a formal specification language for this model is defined by using BNF grammar. Compared with those in literatures, it is simpler because of only concerning the algebraic properties of cryptographic protocols.展开更多
The bad behaviors of some users and the drawbacks of public bicycles have hindered the promotion of public bicycles. The current problems include low utilization rate, uneven distribution, high loss rate and insecure ...The bad behaviors of some users and the drawbacks of public bicycles have hindered the promotion of public bicycles. The current problems include low utilization rate, uneven distribution, high loss rate and insecure lock. However, there is few feasible research in this new field. To address these issues of public bicycles, we propose a public bicycle operating system（PBOS）. PBOS involves three key technologies： 1） To acquire a dynamic password and realize bicycle self-rescue, we devise an intelligent lock that utilizes the Internet of Things（IoT） to establish Bluetooth connection with user＇s mobile phone. 2） To avoid bicycle loss and improve the security of data transmission, we design a space-time security protocol to work between bicycle＇s intelligent lock, mobile app, and server. 3） To increase the average utilization rate and distribution, we present a cooperative game model for bicycle scheduling. Finally, we evaluate the performance and validate the theoretical properties of PBOS through extensive simulations.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
面向“鹊桥”通导遥综合星座系统多航天器之间的通信需求,针对现有深空通信存在的时延长、链路中断频繁、协议不统一等难点,提出了由地面网、地轨网、月面网、月轨网、行星表面网和行星轨道网组成的一体化跨域网络拓扑架构以及融合国际...面向“鹊桥”通导遥综合星座系统多航天器之间的通信需求,针对现有深空通信存在的时延长、链路中断频繁、协议不统一等难点,提出了由地面网、地轨网、月面网、月轨网、行星表面网和行星轨道网组成的一体化跨域网络拓扑架构以及融合国际空间数据系统咨询委员会(Consultative Committee for Space Data Systems,CCSDS)、欧洲空间标准化组织(European Cooperation for Space Standardization,ECSS)和互联网工程指导组(Internet Engineering Task Force,IETF)协议体系的分层网络协议架构以实现器间、器地和器内通信的统一协议配置。通过地月链路仿真实验表明,束协议(Bundle Protocol,BP)/利克莱德传输协议(Licklider Transmission Protocol,LTP)在高延迟、高丢包率的深空通信环境中有效吞吐量可达90%以上,显著优于传输控制协议(Transmission Control Protocol,TCP)、基于用户数据报协议(User Datagram Protocol,UDP)的低时延的互联网传输层协议(Quick UDP Internet Connection,QUIC)和CCSDS文件传输协议(CCSDS File Delivery Protocol,CFDP)。最后对架构设计与验证、网络信息服务、高可靠传送、智能高效路由等星座系统一体化组网的相关关键技术进行了展望。可为未来“鹊桥”星座系统的一体化网络构建提供技术支撑,具有重要的工程意义。展开更多
近年来存储行业经历了巨大的变革,以固态硬盘(solid state drive, SSD)为代表的半导体存储设备迅猛发展,在性能上显著超越了通过磁头移动寻址的机械硬盘(hard disk drive, HDD).目前支持SSD的2种协议主要包括非易失性内存主机控制器接...近年来存储行业经历了巨大的变革,以固态硬盘(solid state drive, SSD)为代表的半导体存储设备迅猛发展,在性能上显著超越了通过磁头移动寻址的机械硬盘(hard disk drive, HDD).目前支持SSD的2种协议主要包括非易失性内存主机控制器接口规范(nonvolatile memory express, NVMe)协议与串行SCSI(serial attached small computer system interface, SAS)协议,即SAS. NVMe是专为SSD设计的高性能存储协议,能够很大限度地发挥SSD的性能;而SAS协议则充分考虑数据中心的需求,在提供高可靠性与高可扩展性的同时,兼顾了系统性能与成本的平衡.相对于日益增速的存储介质,针对慢速存储设备所设计的软件栈在一次I/O过程中所耗费的时间开销愈发显著.针对该问题学界及工业界都相继提出了众多解决方案,例如Intel提出的高性能存储开发包(storage performance development kit, SPDK)通过将设备驱动实现在用户空间,并采用轮询感知I/O完成等方式大幅度缩短了NVMe SSD对应用程序的响应时间,极大地提升了整个系统的整体性能.然而之前的研究工作针对SAS SSD存储软件栈的优化非常有限,为此在用户空间实现了针对SAS SSD的软件栈优化.实验结果表明,该优化能够有效缩短存储设备对应用程序的响应时间,提高应用对存储设备的访存效率.此外,为了准确评估I/O栈中存储设备的时间开销,硬件性能测试工具HwPerfIO被提出,能够消除大部分软件开销的影响以测得更加准确的存储设备性能.展开更多
文摘The architecture and protocols of Internet can't work well in space environments. To form a reliable and safe space network, characteristics of space communication network one discusse, brief synthesis is performed for consultative committee for space data system (CCSDS) space communications protocol standards (SCPS), and a model accounting for data security problem of space-earth integrated network is provided.
文摘The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport Protocol (DR-TCP) for point-to-point communication in deep space exploration missions. The issues related to deep space communication protocol design and the areas where modifications are necessary are investigated, and a protocol is designed that can provide good throughput to the applications using a deep space link. The proposed protocol uses a cross layer based approach to find the allocated bandwidth and avoids initial bandwidth estimation. A novel timeout algorithm estimates the timeout duration with an objective to maximize throughput and avoid spurious timeout events. The protocol is evaluated through extensive simulations in ns2 considering high RTT values typically seen in Lunar and Mars Exploration Networks under different conditions of packet error rates. DR-TCP provides a significant increase in the throughput as compared to traditional transport protocols under the same conditions. A novel adaptive redundant retransmission algorithm is also presented to take care of the high PER in deep space links. The effect of the Retransmission Frequency has been critically analyzed considering both Lunar and Deep Space scenarios under different levels of PER. The results are very encouraging even in high error conditions. The protocol exhibits a RTT independent behavior in throughput, which is the most desirable quality of a protocol for deep space communication.
文摘This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). The primer focus is the telecommand (TC) part of the standard. The implementation of the standard was in the form of DLL functions using C++ programming language. The second objective of this paper was to use the DLL functions with OMNeT++ simulating environment to create a simulator in order to analyze the mean end-to-end Packet Delay, maximum achievable application layer throughput for a given fixed link capacity and normalized protocol overhead, defined as the total number of bytes transmitted on the link in a given period of time (e.g. per second) divided by the number of bytes of application data received at the application layer model data sink. In addition, the DLL was also integrated with Ground Support Equipment Operating System (GSEOS), a software system for space instruments and small spacecrafts especially suited for low budget missions. The SDLP is designed for rapid test system design and high flexibility for changing telemetry and command requirements. GSEOS can be seamlessly moved from EM/FM development (bench testing) to flight operations. It features the Python programming language as a configuration/scripting tool and can easily be extended to accommodate custom hardware interfaces. This paper also shows the results of the simulations and its analysis.
基金Supported by the National Natural Science Foundation of China (No. 60972061,60972062,and 61032004)the National High Technology Research and Development Program of China ("863" Program) (No. 2008AA12A204)
文摘Deep space communications has played an important role in deep space exploration. Compared with common satellite and terrestrial communications, deep space communications faces more challenging environment. The paper investigated the unique features of deep space communica-tions in detail, discussed the key technologies and its development trends for deep space communica-tions.
文摘Specification language is used to provide enough information for the model of the cryptographic protocol. This paper first extends strand space model to dynamic strand model, and then a formal specification language for this model is defined by using BNF grammar. Compared with those in literatures, it is simpler because of only concerning the algebraic properties of cryptographic protocols.
基金Supported by the National Key Research and Development Program of China(2016YFB0501805)the National Natural Science Foundation of China(61573262)
文摘The bad behaviors of some users and the drawbacks of public bicycles have hindered the promotion of public bicycles. The current problems include low utilization rate, uneven distribution, high loss rate and insecure lock. However, there is few feasible research in this new field. To address these issues of public bicycles, we propose a public bicycle operating system（PBOS）. PBOS involves three key technologies： 1） To acquire a dynamic password and realize bicycle self-rescue, we devise an intelligent lock that utilizes the Internet of Things（IoT） to establish Bluetooth connection with user＇s mobile phone. 2） To avoid bicycle loss and improve the security of data transmission, we design a space-time security protocol to work between bicycle＇s intelligent lock, mobile app, and server. 3） To increase the average utilization rate and distribution, we present a cooperative game model for bicycle scheduling. Finally, we evaluate the performance and validate the theoretical properties of PBOS through extensive simulations.
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.
文摘面向“鹊桥”通导遥综合星座系统多航天器之间的通信需求,针对现有深空通信存在的时延长、链路中断频繁、协议不统一等难点,提出了由地面网、地轨网、月面网、月轨网、行星表面网和行星轨道网组成的一体化跨域网络拓扑架构以及融合国际空间数据系统咨询委员会(Consultative Committee for Space Data Systems,CCSDS)、欧洲空间标准化组织(European Cooperation for Space Standardization,ECSS)和互联网工程指导组(Internet Engineering Task Force,IETF)协议体系的分层网络协议架构以实现器间、器地和器内通信的统一协议配置。通过地月链路仿真实验表明,束协议(Bundle Protocol,BP)/利克莱德传输协议(Licklider Transmission Protocol,LTP)在高延迟、高丢包率的深空通信环境中有效吞吐量可达90%以上,显著优于传输控制协议(Transmission Control Protocol,TCP)、基于用户数据报协议(User Datagram Protocol,UDP)的低时延的互联网传输层协议(Quick UDP Internet Connection,QUIC)和CCSDS文件传输协议(CCSDS File Delivery Protocol,CFDP)。最后对架构设计与验证、网络信息服务、高可靠传送、智能高效路由等星座系统一体化组网的相关关键技术进行了展望。可为未来“鹊桥”星座系统的一体化网络构建提供技术支撑,具有重要的工程意义。
文摘近年来存储行业经历了巨大的变革,以固态硬盘(solid state drive, SSD)为代表的半导体存储设备迅猛发展,在性能上显著超越了通过磁头移动寻址的机械硬盘(hard disk drive, HDD).目前支持SSD的2种协议主要包括非易失性内存主机控制器接口规范(nonvolatile memory express, NVMe)协议与串行SCSI(serial attached small computer system interface, SAS)协议,即SAS. NVMe是专为SSD设计的高性能存储协议,能够很大限度地发挥SSD的性能;而SAS协议则充分考虑数据中心的需求,在提供高可靠性与高可扩展性的同时,兼顾了系统性能与成本的平衡.相对于日益增速的存储介质,针对慢速存储设备所设计的软件栈在一次I/O过程中所耗费的时间开销愈发显著.针对该问题学界及工业界都相继提出了众多解决方案,例如Intel提出的高性能存储开发包(storage performance development kit, SPDK)通过将设备驱动实现在用户空间,并采用轮询感知I/O完成等方式大幅度缩短了NVMe SSD对应用程序的响应时间,极大地提升了整个系统的整体性能.然而之前的研究工作针对SAS SSD存储软件栈的优化非常有限,为此在用户空间实现了针对SAS SSD的软件栈优化.实验结果表明,该优化能够有效缩短存储设备对应用程序的响应时间,提高应用对存储设备的访存效率.此外,为了准确评估I/O栈中存储设备的时间开销,硬件性能测试工具HwPerfIO被提出,能够消除大部分软件开销的影响以测得更加准确的存储设备性能.
