空间信息传输网络层协议分析

网络层处于空间信息传输协议体系的关键层,其协议选择关系着能否实现未来航天任务提出的动态数据传输、灵活路由选择、与地面网络的互操作性等技术要求。对CCSDS空间分包协议、SCPS-NP协议和IP协议等可用于空间通信的网络层协议进行了总结分析,并从功能、地址空间、协议开销和技术成熟度及产品支持等方面进行了比较。可以看出,IP协议是未来空间任务的合理选择。对于没有空间链路路由选择的任务,可先使用CCSDS空间分包协议解决动态数据传输问题。     

CCSDS分包遥控协议分析

空间数据系统委员会（CCSDS,Consultative Committee for Space Data System）所发布的标准在窄间数据通信领域起着极其重要的作用,很多标准已经转化为ISO国际标准。分包遥控（TC）协议主要用于地面对航天器的控制,其安全性和准确性对航天器至关重要。着重对TC协议进行通信进程演算（CCS）,通过演算没有发现协议中有死锁与活锁等问题,为今后CCSDS协议（如PSLS）的开发提供了有效的分析方法。     

空间通信协议SCPS／CCSDS研究综述

随着各国对外层空间资源的探索、开发和利用,空间通信系统及其互联技术的研究和开发受到越来越多的重视。空间数据系统咨询委员会（CCSDS）为遥测、遥控和高级在轨系统（AOS）制定了一系列建议标准,包括TM／TC／AOS空间数据链路协议、空间通信系统联网协议以及空间系统的端到端应用协议等。文章分析了CCSDS空间通信系统体系结构．以及空间通信协议标准（SCPS）协议体系,探讨了SCPS／CCSDS空间通信协议族配置实例．并进行了深入的技术分析。     

CCSDS空间链路协议体系分析

在CCSDS空间链路层协议上传递IP数据报,实现空间网络和地面网络的无缝连接是未来空地通信发展的主要方向。本文以CCSDS空间链路协议的发展为出发点,分别介绍了常规在轨系统（COS）空间链路协议、高级在轨系统（AOS）空间链路协议和邻近-1（prox-1）空间链路协议的业务类型和功能,分析了协议的层结构、基本原理和关键技术,并对我国开展相关研究提出了建议。     

中继终端设备的天地网关功能设计与性能测试

近年来,空间网络协议大力发展,CCSDS空间网络协议体系已成为事实上的标准。基于跟踪与数据中继卫星系统（TDRSS）地面站中低速中继终端设备进行相应改造,增加网关路由板卡,加载CCSDS空间传输协议软件,将原来的中低速中继终端设备改造成带有路由网关功能的中低速中继终端设备。在此基础上,采用两台增加路由网关功能的中低速中继终端设备以及信道模拟器搭建天地网络演示验证系统,并分别对采用TCP协议和PEP增强协议作为传输层协议的HTTP应用进行了性能分析比对,证明PEP增强协议更能适应天地网络传输。     

MPLS宽带网络技术讲座——第3讲 CR—LDP信令协议与RSVP扩展协议

CR－LDP（Constraint-Based LDP）信令协议和RSVP（ Resource Reservation Protocol）扩展协议是IETF推荐的两种MPLS控制协议,它们分别是在LDP信令协议和RSVP协议的基础上发展起来的。本文首先介绍了RSVP协议、RSVP扩展协议和CR－LDP信令协议的基本概念和技术特点,接着重点结合实际应用对它们进行分析比较,最后讨论了这两种控制协议的应用前景。     

MPLS宽带网络技术讲座——第3讲 CR-LDP信令协议与RSVP扩展协议

CR－LDP（Constraint－Based LDP）信令协议和RSVP（Resource Reservation Protocol）扩展协议是IETF推荐的两种MPLS控制协议,它们分别是在LDP信令协议和RSVP协议的基础上发展起来的。本文首先介绍了RSVP协议、RSVP扩展协议和CR－LDP信令协议的基本概念和技术特点,接着重点结合实际应用对它们进行分析比较,最后讨论了这两种控制协议的应用前景。     

SIP协议在MF-TDMA卫星通信系统中的应用与改进

为了解决MF-TDMA（Multi-Frequency Time Division Multiple Access）卫星通信系统上应用VOIP（Voice over Internet Protocol）技术的问题,提出了将SIP（Session Initiation Protocol）协议与MF-TDMA卫星通信系统相...     

数据中继卫星系统的数据传输协议研究

首先介绍了美国中继卫星系统的基本概况,给出了其系统组成框图和连接关系,依据中继卫星系统数据传输任务和数据传输需求,并在分析比较ESA和CCSDS的星地数据传输管理协议的基础上,提出了使用CCSDS组织的AOS建议书作为数据中继卫星系统的数据传输协议建议,给出了数据传输帧的定义和初步操作建议。     

实现CCSDS标准的测控网设计

随着空间数据系统咨询委员会(CCSDS)提出的建议被越来越多的空间组织及国家所采纳,如何使本国的测控网实现或兼容CCSDS的各种建议成为测控领域一个日益受到重视的研究课题。首先分析了CCSDS建议的体系和发展趋势。在此基础上,提出了测控网各部分实现CCSDS建议的基本方法,并对各种方法进行了分析比较。     

DTN performance analysis of multi-asset Mars-Earth communications

The delay-/disruption-tolerant networking (DTN) architecture is considered the key enabling technology for future space communications, as confirmed by the current standardization within CCSDS and the experiments carried out onboard the International Space Station. Despite the scientific community efforts to analyze DTN architecture performance, most of the studies have focused on individual protocols, or have considered simple test cases, thus missing a whole system view. To bridge these research gaps, this paper presents a comprehensive analysis of DTN performance in Mars-Earth communications, considering a realistic and complex end-to-end scenario, where multiple assets and multiple data flows are involved, as envisioned for future space missions. To this end, a virtualized testbed based on ION software was used for an extensive emulation campaign, focusing particularly on Bundle and Licklider Protocol interaction with the CGR routing algorithm.     

Error counter-based negative acknowledgement mode in CCSDS file delivery protocol

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 terrestrial 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.     

Satellite image compression by post-transforms in the wavelet domain

This paper proposes a novel compression scheme with a tunable complexity-rate-distortion trade-off. As images increase in size and resolution, more efficient compression schemes with low complexity are required on-board Earth observation satellites. The standard of the Consultative Committee for Space Data Systems (CCSDS) defines a strip-based compression scheme with the advantages of a low complexity and an easy rate control [CCSDS, Image Data Compression Recommended Standard CCSDS 122.0-B-1 Blue Book, November 2005]. However, future mission specifications expect higher performance in terms of rate-distortion. The scheme proposed in this paper intends to perform better than the CCSDS standard while preserving low complexity and easy rate control. Moreover, to comply with existing on-board devices, the proposed core compression engine still uses the wavelet transform but in association with a linear post-processing inspired from the bandelet transform. The post-transform decomposes a small block of wavelet coefficients on a particular basis. This basis is adaptively selected within a predefined dictionary by rate-distortion optimization. The computational complexity depends upon the dictionary size and of the basis structure. An extremely simple dictionary, reduced to the Hadamard basis, is proposed. The post-transform efficiency is illustrated by experiments on various Earth observation images provided by the French Space Agency (CNES).     

QoS enhancement in space data communication: a network coding approach

With the rapid increase of space applications, the amount of information to be transmitted between spacecrafts and ground stations increases exponentially and space–sky–ground Transport Control Protocol (TCP) network is highly demanded. However, the traditional TCP cannot be directly applied to space data communication. This article deeply studies the TCP/Network Coding (NC), which can effectively improve terrestrial wireless communication system throughput. Combined with characteristics of Space Communication Protocol Specification-Transport Protocol (SCPS-TP) and advantages of terrestrial TCP/NC, an improved protocol referred to as SCPS-TP/NC, is proposed for space data communication. This article provides detailed process of protocol design, mathematical modelling and throughput analysis of the proposed SCPS-TP/NC. Finally, we implement the SCPS-TP/NC protocol and evaluate its performance by Network Simulator (Version 2). Simulation results show that SCPS-TP/NC can effectively increase the end-to-end system throughput, reduce the packet loss rate, shorten the transmission delay and improve the Quality of Service (QoS) of space data communication to a certain degree.     

Regenerative pseudo‐noise (PN) ranging sequences for deep‐space missions

Space Agencies are currently considering replacing conventional ranging systems with regenerative schemes for future demanding interplanetary missions. The Consultative Committee for Space Data Systems (CCSDS) in charge of standardization among Space Agencies is studying both Pseudo‐Noise (PN) and Pseudo‐Noise‐Like (PNL) sequences and is due to generate a recommended standard (Blue Book) by 2007. The present paper treats the PN schemes under consideration by CCSDS, which include the weighted‐voting Tausworthe PN ranging scheme and the balanced weighted‐voting Tausworthe PN ranging scheme. Copyright © 2007 John Wiley & Sons, Ltd.     

Regenerative pseudo‐noise‐like (PNL) ranging sequences for deep‐space missions

Space agencies are currently considering replacing conventional ranging systems with regenerative schemes for future demanding interplanetary missions. The Consultative Committee for Space Data Systems (CCSDS) in charge of standardization among Space Agencies is studying both Pseudo‐Noise (PN) and Pseudo‐Noise‐Like (PNL) sequences and intends to generate a recommended standard (Blue Book) by 2007. The present paper treats the PNL schemes under consideration by CCSDS, with emphasis on the scrambled weighted‐voting Stiffler PNL ranging‐sequence scheme, which is proposed herein and which appears to be superior to all other PN and PNL ranging schemes. Copyright © 2007 John Wiley & Sons, Ltd.     

CCSDS中位平面编码的FPGA优化实现

CCSDS图像压缩算法是空间数据系统咨询委员会针对深空探测图像制定的图像压缩标准.该算法的码率可控、复杂度较低,而且算法结构适合于硬件实现,支持对空间数据的高速实时处理.给出了基于可编程逻辑电路硬件的位平面编码算法的设计与实现方法,并通过分析直流、交流系数编码过程中各模块内部和模块间的关系,设计了流水线,使系统处理速度...     

基于SCPS协议的快速自组织可重构天基信息网组网

根据快速自组织天基信息网的特点,设计了组网模型,分析了所需协议的结构,提出了基于空间通信协议规范(SCPS)协议的快速自组织天基信息网的组网抗毁策略,优化了天基信息系统运行效率,提高了其生存能力.