基于TD-SCDMA的低轨星座卫星通信系统接入技术

本文对低轨星座卫星通信系统采用TD-SCDMA多址接入技术的可行性进行了初步论证,通过对低轨星座卫星通信特点的分析,提出在现有TD-SCDMA系统基础上进行适应性改造,满足卫星通信的要求,使得低轨星座卫星通信系统最大限度的重用已有的成熟技术,作为地面移动通信的延伸和补充,这将大大提高低轨星座卫星通信系统的经济性、可运营性、易维护性和可持续发展能力。     

星座卫星通信网安全预警机制研究

针对卫星通信面临的安全威胁,星座卫星通信网必须建立有效的安全预警机制。通过分析星座卫星通信网安全预警机制需求,给出了星座卫星通信网安全预警机制的总体结构,最后对星座卫星通信网安全预警机制的关键技术进行了讨论。     

低轨星座卫星通信系统移动性管理的思考

在移动通信发展的过程中,切换一直是移动性管理的核心.本文总结了低轨星座卫星通信系统切换的特点,针对低轨星座卫星通信系统的需求,对国内外低轨星座的切换技术进行总结与分析,并提出几点关于低轨星座切换技术的研究建议.     

卫星通信系统安全技术综述

由于空间环境的特殊性,地面网络中的安全机制不能直接用于卫星通信.介绍了卫星通信系统安全技术的最新进展.首先从空间信道环境、卫星节点能力、星座网络结构等方面指出了卫星通信系统的安全弱点.然后总结了物理层、数据链路层、网络层和传输层所面临的安全威胁和防护对策.着重介绍了抗损毁技术、抗干扰技术、认证机制和密钥管理协议,并对有代表性的安全策略进行了分析、对比和讨论.最后对卫星通信系统安全技术发展方向做出预测.     

区域覆盖共地面轨迹星座的优化设计

该文讨论了使用中轨共地面轨迹星座建立区域覆盖卫星通信系统的优化设计方法。在深入研究共地面轨迹星座参数特性的基础上,提出了一种能够完整描述该类型星座的编码标识方法,推导了星座与星座的等价关系,讨论了利用该类型星座实现区域覆盖时的优化方法,给出了适用于我国的多个优化星座方案实例。从仿真结果可以看出,该类型星座能够以较少数量的卫星为我国提供良好的覆盖性能,适于我国的区域覆盖卫星通信系统采用。     

国外新兴商业低轨卫星通信星座发展述评

近年来,在商业投资的推动下低轨卫星通信星座网络快速发展,不断有新的商业低轨卫星通信星座计划涌现。实际上20世纪90年代也曾掀起过低轨通信卫星星座浪潮,但结果却未能达到最初的设想。总结了20世纪90年代提出的低轨通信卫星计划的经验教训,概述了目前典型的新兴低轨商业卫星通信星座特性及发展现状,根据之前星座的经验教训提出了对当前商业低轨卫星通信星座发展的思考。     

我国中低轨移动卫星星座设计及动态仿真

本文讨论中低轨移动卫星通信的系统设计问题,包括星座设计、覆盖率统计和通信线路计算等问题.运用统一建模语言UML、面向对象可视化编程语言Delphi5.0、科学计算语言Matlab5.3、动画制作软件Animator等工具研制了中低轨移动卫星通信系统设计综合软件,并以此设计了我国中低轨移动卫星通信系统的星座方案各一套,同时完成了星座实时动态演示,并能实时对全球、中国、北美、欧洲进行覆盖率动态统计和通信线路计算等.     

基于移动性的星座卫星通信网络管理体系结构研究

在分析低轨星座卫星通信系统特点的基础上,提出一种适用于低轨星座卫星通信网络管理的体系结构,并针对管理体系中被管理终端设备的动态特性,进行了移动性管理策略的研究,设计了适用于此系统的终端设备接入认证策略和基于距离的动态位置更新策略,该策略有效地降低终端设备移动性对网络管理效率的影响.     

低轨星座系统覆盖特性仿真分析

星座卫星通信系统是一个复杂的大系统，投资巨大，进行科学的评估与性能分析是正确决策的基础。星座覆盖特性分析是星座通信系统设计的重要方面。     

军用星座卫星通信抗干扰技术体制

星座卫星通信系统可以实现全球无缝隙覆盖,是地面通信网络的重要补充。星座系统可根据不同的应用,如海湾战争中“铱”系统为美军发挥了重要作用。     

Network and common channel signalling aspects of dynamic satellite constellations

This paper discusses networking issues associated with the provision of L/S-band personal satellite communications. Both the UMTS and IMT-2000 third generation mobile communication concepts have identified the need for a satellite component as part of their overall structure. The work is mostly based on the ESA-developed medium altitude global satellite system (MAGSS-14).¹ It is, therefore, mainly relevant to MEO (medium earth orbit) constellations but most ideas can also be extended to LEO (low earth orbit) constellations. After examining user and service requirements the specific networking issues associated with personal satellite communications are reviewed. A network architecture is then proposed which takes these restrictions into account. Based on this network architecture, network signalling requirements, more specifically those relevant to network common control channels, are estimated.     

Analysis of system parameters for LEO/ICO-satellite communicationnetworks

Currently many efforts are undertaken to develop and install communication networks based on low Earth orbit (LEO) and intermediate circular orbit (ICO) satellites. However, many problems are to be solved before the final operation of such networks. This paper deals with basic design problems of LEO/ICO-based networks. The topology of the satellite network is considered and estimates for the number of satellites necessary, orbits and number of communication channels per satellite are derived. The features and consequences of intersatellite links are discussed. The number of communication channels per link is derived with a more elaborate model. This includes the radio links from the satellites to mobile users and to gateways, as well as intersatellite links and terrestrial lines. We introduce a formal model for LEO/ICO based networks and propose a method for the evaluation of the link capacities, given the network topology and the traffic requirements. As an example, two constellations are investigated in detail. One of these constellations is the Iridium system proposed by Motorola, the other is the LEONET concept developed in an ESA study. Finally, the influence of unequal traffic distribution is discussed     

LEO/MEO卫星通信系统发展展望

本简述了LEO/MEO卫星通信系统的主要特点，并介绍了几个典型的LEO/MEO卫星通信系统，如Iridium、Globalstar、ICO、Teledesic、Skybridge系统。还从星座、频率、星上处理及星际链路、无线技术、网络技术等方面讨论了LEO/MEO卫星通信系统的发展趋势和研究热点。     

Satellite visibility in Northern Europe based on digital maps

This paper presents the calculation of satellite visibility and system availability based on digital elevation maps. New models for satellite visibility are derived for both non‐geostationary orbiting satellite constellations and geostationary satellites. Regression models for satellite visibility and average number of visible satellites based on easily available surface roughness variables are developed and tested. Cumulative distributions for the percentage of time that Iridium satellites are visible, taking terrain obstacles into account, are calculated and the relation between satellite visibility and system availability is discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

An overview of propagation factors influencing the design of mobilesatellite communication systems

A number of mobile satellite communication systems are currently being developed that do not make use of satellite constellations based on the traditional geostationary orbit used for communication satellites. This paper describes some of the propagation-related factors that influence the constellation for some of these systems, along with mitigation techniques that may be employed to overcome the dominant propagation-related impairments. For systems operating at VHF and UHF, the effects of mobile environment factors such as blockage and multipath are the dominant propagation factors in the link design. Mitigation techniques, such as satellite diversity, can be usefully employed to help overcome the effects of blockage, which may become increasingly severe at low elevation angles. The driving factor for constellation design is to provide a sufficiently high probability of multiple (dual or more) satellite visibility over the latitudes of interest     

Machine Learning and Deep Learning powered satellite communications: Enabling technologies,applications, open challenges,and future research directions

The recent wave of creating an interconnected world through satellites has renewed interest in satellite communications. Private and government-funded space agencies are making advancements in the creation of satellite constellations, and the introduction of 5G has brought a new focus to a fully connected world. Satellites are the proposed solutions for establishing high throughput and low latency links to remote, hard-to-reach areas. This has caused the injection of many satellites in Earth's orbit, which has caused many discrepancies. There is a need to establish highly adaptive and flexible satellite systems to overcome this. Machine Learning (ML) and Deep Learning (DL) have gained much popularity when it comes to communication systems. This review extensively provides insight into ML and DL's utilization in satellite communications. This review covers how satellite communication subsystems and other satellite system applications can be implemented through Artificial Intelligence (AI) and the ongoing open challenges and future directions.     

Web traffic capacity of multi-beam GEO and MEO mobile satellite systems

An investigation into the downlink Web traffic capacity of W-CDMA land mobile satellite communication systems for Geostationary (GEO) and Medium Earth Orbit (MEO) constellations is presented. It is shown that the effect of power control errors on the Web traffic capacity severely degrades the performance of mobile satellite systems. It is also shown that the use of the proposed macrodiversity system is to mitigate the effect of power control errors, and consequently increases the Web traffic capacity of multi-beam GEO and MEO mobile satellite systems     

A comparative study of solar interference on the iridium and MSS constellations

Radio frequency cross-links are the preferred communication medium for low earth orbit (LEO) satellite networks today. However, future cross-link designs may be expected to deploy laser crosslinks to increase communication bandwidth. These cross-links are rendered inoperative when incident with high level background radiation sources such as the Sun. The Iridium and Multiple Satellite System (MSS) are two well-researched constellations in the literature and are ideal candidates for the investigation of solar interference on point-to-point constellations. In this paper a comparison of the impact of solar radiation on link availability for these two systems is presented. Evaluation of link availability based on the motions of the bodies in question is computationally infeasible. It is therefore necessary to reduce the state space to a manageable computing basis by reformulating the problem domain and by simulation. In this report the development of an algorithm and a software simulation tool to analyse the two constellations will be presented, and the results of laser cross-link availability will be discussed. The technique introduced here may be generalized to study a variety of different constellations.     

共地面轨迹移动卫星通信星座设计

本文从移动卫星地面轨迹的特点出发研究了一种共地面轨迹移动卫星星座的设计方法,并借助于计算机模拟和专业卫星通信工具软件对我国区域进行了设计,在选定轨道周期为1／4个恒星日,偏心率为0．158,轨道倾角为63．4°的情况下,4颗共地面轨迹卫星即可对我国大陆（北纬20°至55°）基本达到连续覆盖,平均仰角大于48°．     

区域覆盖卫星系统的共地面轨迹星座实现

研究了使用中轨共地面轨迹星座实现区域覆盖卫星通信系统的优化方法,提出了一种能够完整描述该类型星座的编码标识方法,给出了多个适用于我国的星座方案实例。基于时变的业务分布密度特性对星座方案的参数进行了调整,使得星座的覆盖特性与业务分布密度更加一致。仿真结果表明该类型星座能够以较少数量的卫星为我国提供良好的覆盖性能。