Ka 宽带通信卫星天线技术现状与发展趋势研究

本文介绍了用于宽带多媒体业务的Ka 宽带通信卫星，总结了卫星及其星载天线的技术现状、关键技术和发展趋势，最后讨论了国内开展Ka 宽带通信天线技术研究的意义及发展前景。     

宽带卫星通信概述

介绍了宽带卫星通信的概念及发展现状，讨论了卫星ATM、卫星IP、星上处理技术，分析了宽带卫星通信中的雨衰、QoS问题，阐述了宽带卫星通信的发展策略及趋势。     

近期宽带卫星应用技术展望

本介绍了宽带卫星的技术要求，要解决的问题，主要技术及其构思，指出基于地球静止轨道上的具有星上处理功能和多波束覆盖的宽带卫星可能会是近期发展较快的卫星系统，ATM技术适合用来完成宽带卫星星上处理功能。     

亚太地区卫星宽带业务现状及其发展趋势

世界宽带业务正飞速发展，卫星宽带业务方兴未艾。通过对未来几年亚太地区卫星宽带业务收入的预测，及主要卫星宽带业务在该地区的市场份额预测，并以几个主要亚太国家为例，分析了亚太卫星宽带市场的现状和发展趋势，得出结论，虽然卫星宽带业务面临来自地面宽带的竞争，但仍有广阔的市场前景。     

海事卫星宽带技术航空应用探析

本文介绍了海事卫星航空通信系统的组成,分析了海事卫星宽带网络系统的技术特点,探讨了海事卫星宽带技术在航空安全通信服务、客舱通信服务、GSM客舱服务、航空飞行管理等领域的技术应用,对海事卫星宽带技术在航空领域的发展前景进行了展望。     

国外宽带卫星系统技术发展概况

宽带卫星系统是通信技术的一部分，日益普及的宽带通信服务、快速发展的因特网和计算机技术为宽带卫星系统开辟了广阔的前景。同步和非同步地球卫星所组成的卫星通信网络是卫星宽带通信的重要载体。分别介绍了同步和非同步轨道卫星系统的特点，探讨了这两种系统在实现频谱共享的过程中所遇到的问题。     

Ka频段卫星宽带业务在北美初见成效

Ka频段卫星宽带业务在上世纪90年代未曾经被视为最有市场前景的卫星通信业务，但随着光缆通信技术的飞速发展和价格的大幅下降，陆基宽带通信较之天基卫星宽带业务形成了明显的竞争优势。因此过去5年来美欧大部分已经或将要上马的中低轨道大型卫星宽带工程相继退出或改作其它用途。另一些卫星公司开始转向静止轨道Ku频段通信卫星，试图开拓和培育面向政府和工商企业的卫星宽带市场。     

基于DVB-RCS和WiMAX的卫星宽带无线接入体系设计

卫星宽带通信已成为目前研究的热点.现有的DVB-RCS卫星无线接入标准以物理层规范为主,尚未构成完整的卫星宽带无线接人体系.本文基于DVB-RCS技术,针对卫星宽带无线接入的需求和特点,结合地面WiMAX宽带无线接入技术,给出了卫星宽带无线接人体系的功能架构设计,并具体分析了各主要功能的设计与实现方法.     

卫星-CATV-Internet宽带网

本文从介绍宽带多媒体网络的技术要求开始,进一步分析宽带卫星多媒体通信系统如何符合宽带多媒体网络的技术要求,卫星与Internet、卫星VSAT－CATV－Internet综合网络,最后介绍几种最新宽带卫星多媒体通信系统。     

卫星综合宽带网络

随着欧洲本地化宽带网络的迅速发展和延伸，使国际宽带连接的采用成为当务之急，而卫星系统具备的性能可以很好地满足这一需求，本文首先介绍了专用于宽带网互连的基于卫星的系统的设计，然后示例分析了作为初创ＲＡＣＥⅡ（欧洲先进通信技术研究与开发）的一部分的ＣＡＴＡＬＹＳＴ系统，并结合考虑了正在进行中的试验的特征，最后，还探讨了将来采用卫星系统全面补充地面网络的技术发展的可能性。     

走向宽带化的VSAT卫星通信

受数据音频视频广播、计算机卫星宽带交互接入和音视频会议等业务的推动,VSAT卫星通信网向宽带业务发展巳成为必然趋势。分别对应以上业务的VSAT卫星通信网也日益趋于融合成一个统一的宽带VSAT通信网。发展宽带VSAT通信网的关键技术涉及到宽带数据广播、宽带多址接入、卫星通信规程、网络综合管理和宽带虚拟子网等。     

基于DVB-RCS的VSAT宽带卫星通信技术与应用

介绍了VSAT数据网原理、卫星通信系统宽带化的发展趋势及DVB-RCS开放标准。通过介绍基于DVB-RCS的VSAT宽带卫星通信系统在工程中的应用实例,其中包括系统业务与特点,以及各子系统的基本配置等,可以得出,随着网络和业务的宽带化,VSAT卫星通信系统正在从传统的窄带向宽带系统转变。在现有技术中,基于DVB-RCS...     

Broadband satellite networks-the global IT bridge

Next-generation broadband satellite networks are being developed to carry bursty Internet and multimedia traffic in addition to the traditional circuit-switched traffic (mainly voice) on a global basis. These satellites provide direct network access for personal applications as well as interconnectivity to the terrestrial remote network segments. The main requirement in success of these networks is that they should be able to transmit high data rate traffic with prescribed quality of service (QoS). Thus, the broadband satellite network has no choice other than the rise of ATM technology and to be optimized for Internet-based traffic. ATM is the promising technology for supporting high-speed data transfer potentially suitable for all varieties of private and public telecommunications networks. IP, on the other hand is the fast-growing Internet layer protocol that is applicable over any data link layer Internet-based applications are the emerging source of traffic in the future wireless networks and broadband satellite networks should consider Internet as the primary service. In this paper, we discuss the traditional ATM and wireless ATM networks and explain the characteristics of the wireless IP networks. The paper then uses those concepts in defining the criteria for the broadband satellite networks such as the QoS and traffic management. Application of the broadband satellite networks is also proposed     

IPv6 networks over DVB‐RCS satellite systems

Satellite plays an important role in global information infrastructure (GII) and next generation networks (NGNs). Similarly, satellite communication systems have great advantages to support IPv6 (Internet Protocol version 6) networks as a technology that allows universal access to broadband e‐services (audio, video, VPN, etc.). In the context of DVB‐S2 (digital video broadcast‐satellite) and DVB‐RCS (digital video broadcast‐return channel via satellite) standards, this paper presents the current SatSix project (satellite‐based communications systems within IPv6 networks) within the European 6th Framework Programme, which is implementing innovative concepts and effective solutions (in relation with the economical cost) for broadband satellite systems and services using the technology presented above. This project is promoting the introduction of the IPv6 protocol into satellite‐based communication systems. Moreover, through SatSix, the industry is addressing the next generation Internet, IPv6. It also enhances its competitive position in satellite broadband multimedia systems by exploiting the common components defined by the European DVB‐S2 and DVB‐RCS satellite broadband standards. Copyright © 2007 John Wiley & Sons, Ltd.     

Critical issues of onboard switching in DVB-S/RCS broadband satellite networks

The next generation of broadband satellite networks is challenged to accommodate multimedia services while concurrently integrating with terrestrial IP networks. With IP applications dominating the Internet, carrying IP traffic over the satellite has been under intensive study. Originally developed to bring digital television home through satellites, the DVB-S and DVB-RCS standards empower interactive satellite communications with economical standardized satellite terminals. Furthermore, onboard switching technology is increasingly gaining attention, due to optimized bandwidth usage, fully meshed network topology through one satellite hop, and quality of service guarantee. This article investigates the onboard switching technologies in DVB-S/DVB-RCS broadband satellite networks. Aside from the network system infrastructure and switch hardware architecture, the QoS mechanisms supported by the switch onboard the satellite are discussed in depth.     

A flow control scheme using broadcast information for Internet services in multiple-beam satellite networks

A new flow control scheme improving performance of the future broadband satellite networks is proposed and analyzed in this paper. The proposed scheme is particularly suitable for the Internet-based services in broadband satellite networks. The complexity of the proposed scheme is comparable with the existing flow control techniques, as it does not require the additional information to be provided by either the satellite or the Earth stations. The throughput and the satellite queue size performances of the proposed scheme are mathematically analyzed and simulated. The results show the significant improvement in the proposed scheme comparing with the conventional window-based and rate-based flow control techniques. Such a scheme can be used in the future satellite networks, which are an important component in the global information infrastructure (GII).     

Technical issues regarding satellite packet switching

Many concepts for advanced communication satellite networks have recently been proposed. Critical technical issues relating to satellite packet switching for meshed very small aperture terminal networks and broadband networks are addressed. Hardware considerations, networking and testing issues are discussed.     

一种卫星网络中基于Agent的可靠组播传输协议

IP 组播技术是一种可以把单个数据信息同时分发到不同的用户去的网络技术。卫星网络固有的广播信道特性使得它很适合组播应用。然而目前针对卫星网络的可靠组播服务研究很少,虽然已经有一些关于地面Internet组播协议建议,但他们并不适合于卫星网络。在卫星网络组播传输中的一个关键技术是传输协议设计。该文提出一种基于Agent的宽带卫星网络可靠组播传输协议(ASMTP)。该协议利用接收端Agent来实现卫星组播,采用分组级FEC和本地差错恢复纠正传播中的非相关错误和相关错误。在ASMTP中,还实现了流量控制和拥塞控制机制。仿真结果表明,在卫星网络环境中,ASMTP性能优于MFTP(Multicast File Transport Protocol),同时具有较好的网络可扩展性。     

基于IP协议的卫星组网通信关键技术研究

早期卫星组网一般采用地球同步卫星(GEO)作为中继器，而现在的卫星宽带信息网则是通过星间链路(ISL)实现相邻卫星之间直接通信，研究宽带卫星组网技术对于加快我国信息基础设施建设具有极其重要的作用。本首先介绍卫星通过星间链路组网通信的系统模型，然后分析卫星网络IP系统的协议堆栈，并对卫星网络TCP/IP协议各层采用的接口和协议、基本功能、工作方式等进行详细研究，最后对卫星组网通信中涉及的物理层、数据链路层和网络层的关键技术逐一进行了探讨。     

卫星通信向宽带发展的趋势

本文先说明卫星通信值得重视的优点。然后分别简述卫星ATM网、卫星多媒体系统和星上处理与交换 ,旨在介绍卫星通信正向宽带发展的趋势。