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
With the increasing enlargement of network scale and the rapid development of network techniques, large numbers of the network applications begin to appear. Packet capture plays an important role as one basic techniqu...With the increasing enlargement of network scale and the rapid development of network techniques, large numbers of the network applications begin to appear. Packet capture plays an important role as one basic technique used in each field of the network applications. In a high-speed network, the heavy traffic of network transmission challenges the packet capture techniques. This paper does an in-depth analysis on the traditional packet capture mechanisms in Linux, and then measures the performance bottleneck in the process of packet capture. The methods for improving the packet capture performance are presented and an optimized packet capture scheme is also designed and implemented. The test demonstrates that the new packet capture mechanism (Libpacket) can greatly improve the packet capture performance of the network application systems in a high-speed network.展开更多
移动通信系统的演进,离不开先进技术的应用、网络结构的升级和协议栈的改进。文章结合第三代合作伙伴计划(the 3rd Generation Partner Project,3GPP)标准讨论了第五代移动通信(the 5th Generation Mobile Communication Technology,5G...移动通信系统的演进,离不开先进技术的应用、网络结构的升级和协议栈的改进。文章结合第三代合作伙伴计划(the 3rd Generation Partner Project,3GPP)标准讨论了第五代移动通信(the 5th Generation Mobile Communication Technology,5G)协议栈的总体架构。以服务数据适配协议(Service Data Adaptation Protocol,SDAP)层和分组数据汇聚协议(Packet Data Convergence Protocol,PDCP)层为例,阐述接入网协议栈的改进。分析了2个子层的功能、架构、实体、数据传输流程以及协议数据单元(Protocol Data Unit,PDU)格式,为移动通信系统的优化奠定基础。展开更多
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Sponsored by the National High Technology Development Program of China (Grant No. 2002AA142020).
文摘With the increasing enlargement of network scale and the rapid development of network techniques, large numbers of the network applications begin to appear. Packet capture plays an important role as one basic technique used in each field of the network applications. In a high-speed network, the heavy traffic of network transmission challenges the packet capture techniques. This paper does an in-depth analysis on the traditional packet capture mechanisms in Linux, and then measures the performance bottleneck in the process of packet capture. The methods for improving the packet capture performance are presented and an optimized packet capture scheme is also designed and implemented. The test demonstrates that the new packet capture mechanism (Libpacket) can greatly improve the packet capture performance of the network application systems in a high-speed network.
文摘移动通信系统的演进,离不开先进技术的应用、网络结构的升级和协议栈的改进。文章结合第三代合作伙伴计划(the 3rd Generation Partner Project,3GPP)标准讨论了第五代移动通信(the 5th Generation Mobile Communication Technology,5G)协议栈的总体架构。以服务数据适配协议(Service Data Adaptation Protocol,SDAP)层和分组数据汇聚协议(Packet Data Convergence Protocol,PDCP)层为例,阐述接入网协议栈的改进。分析了2个子层的功能、架构、实体、数据传输流程以及协议数据单元(Protocol Data Unit,PDU)格式,为移动通信系统的优化奠定基础。
