移动卫星通信车载站若干关键技术讨论

由于移动卫星通信系统中的车载站在通信过程中是运动的,因此存在卫星功率有限、传输高速业务与移动站低天线增益之间的矛盾;系统有时是在非高斯信道中工作的,电波传播情况复杂;地面终端的天线时刻对准所使用的卫星。对如何利用有限的卫星功率条件,在地面终端的快速移动中,实时传输宽带多媒体业务,涉及卫星的带宽和功率、移动终端能力、天线伺服跟踪等相关问题进行了讨论,给出了设计原则和设计思路。     

Broadband satellite system technologies for effective use of the12-30 GHz radio spectrum

Broadband satellite systems are an integral part of communications technology, aiming to provide a wide range of services to a society that increasingly expects ubiquitous access to broadband telecommunication services. Key drivers behind the development of these systems include rapid growth in the use of the Internet, PC- and TV-based e-commerce and interactive broadcasting services. In the UK, broadband satellite service trials are currently being conducted by BT, amongst others, with a primary objective of providing services to areas where asymmetric digital subscriber line (ADSL) technology has not been deployed. Two key factors for the success of broadband satellite technology lie in the area of overcoming constraints associated with frequency spectrum and orbital resources. This paper provides a review of technologies employed in geostationary (GSO) and nongeostationary (NGSO) satellite networks designed for the provision of broadband services to fixed and portable ground terminals within the 12 to 30 GHz frequency range. After reviewing the system design parameters related to the use of the radio frequency spectrum, consideration is given to the issues involved in sharing spectrum between GSO and NGSO satellite networks     

Transport protocols in multicast via satellite

In a wide variety of broadband applications, there is a need to distribute information to a potentially large number of receiver sites that are widely dispersed from each other. Communication satellites are a natural technology option and are extremely well suited for carrying such services because of the inherent broadcast capability of the satellite channel. Despite the potential of satellite multicast, there exists little support for multicast services over satellite networks. Although several multicast protocols have been proposed for use over the Internet, they are not optimized for satellite networks. One of the key multicast components that is affected when satellite networks are involved in the communication is the transport layer. In this paper, we attempt to provide an overview of the design space and the ways in which the network deployment and application requirements affect the solution space for transport layer schemes in a satellite environment. We also highlight some of the issues that are critical in the development of next generation satellite multicast services. Copyright © 2004 John Wiley & Sons, Ltd.     

Integrated services from high-altitude platforms: a flexible communication system

In this article the provision of integrated services from high-altitude platforms (HAPs) is discussed, and a flexible communication system for HAP-based communications is identified and analyzed, with particular attention to the delivery of broadband services from HAPs to highspeed trains. The high coding gain required by the proposed scenario is achieved through adaptive concatenated coding schemes, while smart antennas operating with adaptive beamforming algorithms are employed at the ground stations. The simulated system performance based on a multi-antenna model of the stratospheric channel is reported, and the use of HAPs in synergy with terrestrial and satellite systems is discussed.     

MIMO场景下的低轨卫星选星算法

低轨(LEO)宽带星座卫星通信作为地面5G无线通信系统的重要补充,始终面临地面可视卫星数量大、传统选星算法计算复杂度高等难题。为实现高效的卫星分组选择算法,基于多输入多输出(MIMO)系统原理,以大尺度路径损耗模型为基础,结合递减卫星选择算法,从而以较低计算复杂度、更快收敛速度有效逼近最优容量性能。该算法在典型LEO星座系统构型下通过数值仿真得到了验证,为未来5G低轨卫星星座通信传输方案设计提供了一种参考思路。     

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...     

In‐line interference mitigation techniques for spectral coexistence of GEO and NGEO satellites

The interest towards the deployment of Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) satellite systems in several frequency bands is increasing due to the requirement of low latency for real‐time systems and high demand of broadband data. When the number of usable Non‐Geostationary (NGEO) satellites, that is, LEO/MEO in space, increases, the frequency coexistence between the NGEO satellite systems with the already existing geostationary (GEO) satellite networks becomes a requisite. In this context, it is crucial to explore interference mitigation techniques between GEO and NGEO systems in order to allow their spectral coexistence. More specifically, in the coexistence scenario of GEO and NGEO satellite networks, in‐line interference may be a serious problem, especially in the equatorial region. In this paper, we provide several frequency sharing studies in the context of the coexistence of an NGEO satellite link with another NGEO/GEO satellite link. Furthermore, we carry out interference analysis between GEO and MEO satellite systems considering the case of the O3b satellite system and propose an adaptive power control technique for both the uplink and downlink scenarios in order to mitigate the in‐line interference. Moreover, we suggest several cognitive solutions for mitigating the in‐line interference and provide future research issues. Copyright © 2014 John Wiley & Sons, Ltd.     

QoS Guarantees in Heterogeneous Systems Consisting of IP Core Networks with Satellite Access

This paper aims at investigating the issue of differentiated QoS provision to services over a heterogeneous terrestrial-satellite infrastructure. In particular, the implementation of a dynamic mapping of the main service classes offered by IP IntServ and DiffServ models over satellite bearer services is investigated.Objective of the research is to enable mobile subscribers to access broadband services offered within a fixed IP core network, through satellite links. This has to be performed while still guaranteeing the same Quality of Service (QoS) offered by the IP IntServ and DiffServ models over the terrestrial segment. In such an environment, the considered traffics derive from multimedia applications and are characterised by real-time and non-real-time constraints as well as variable (VBR) and constant (CBR) bit-rate profiles.     

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.     

面向全球能源互联网的天空地协同卫星通信网络架构

全球能源互联网的监测、调度、授时、同步及定位等业务均需要能提供广域覆盖、泛在灵活接入服务的可靠通信网络。针对该需求,首先分析阐述全球能源互联背景下各种新型业务需求及其特点,并总结各种业务的共性数据特征;然后论述卫星通信技术的特点以及与全球能源互联网业务特点与数据传输需求的高度契合性,最终提出融合卫星通信网络的全球能源互联网天空地协同网络体系架构。其以IP技术为基础,各层网络通过星间、星地、星空、空空、空地以及地面有线、无线链路连接起来,构建全球覆盖的一体化网络体系。     

Ka高通量宽带卫星网络服务应用模式探讨

2017年4月12号第一颗国产高通量宽带卫星-中星16发射成功，Ka高通量宽带卫星网络在国内已经正式运行,本文就国内高通量卫星宽带业务做相应探讨。     

Simulation and analysis of software defined cognitive frequency hopping multi beam satellite system

Traditional multi-beam satellites cannot adapt to the changing traffic because of the fixed bandwidth and cannot adjust dynamically for the traffic load.In the future,the multi-beam broadband satellite system must have great flexibility and can be dynamically adjusted according to the change of the traffic flow.Beam hopping for multi-beam broadband satellite network system has been proposed to improve the traditional multi-beam broadband satellite network system performance,whose principle is to assign different beams to different time slots,rather than the allocation of bandwidth,so that in each time slot,the entire available bandwidth is allocated to each beam,and the time window is periodically applied to the beam selection system ,in the full band hopping mode,the band can be selected optimally in the duration of each beam to meet user transmission bandwidth and delay requirements.With the development of cognitive radio technology,cognitive beam hopping for multi-beam satellite system can further improve the efficiency of spectrum utilization,to meet the growing shortage of spectrum resources,to achieve large-capacity high-bandwidth broadband satellite network system,and to support the rising user service capacity and the transmission efficiency of user services under different load conditions.In addition,software definition technology is also used in satellite networks,which could achieve effective management of satellite resources to improve the utilization of satellite resources.In this paper,the principle of software-defined cognitive hopping multi-beam broadband satellite network system is discussed.The spectrum utilization efficiency and throughput are analyzed,which can be used as a reference for broadband satellite network system design.     

Efficient Integration of IP-Based Terrestrial and Satellite Systems: ARQ Techniques and Inter-Segment Handover

A satellite communication system is an excellent candidate toprovide broadband integrated Internet services to globallyscattered users. The inter-operation between a satellite systemand the existing terrestrial Internet infrastructure introducesnew challenges at different layers. Automatic Repeat reQuest (ARQ)techniques have been introduced at radio link layer to improve theperformance of Transport Control Protocol (TCP)/IP over wirelessterrestrial links, but these techniques are usually dismissed inpresence of high latency links such as satellite links. In thispaper, we will show that a truncated power control can effectivelyimprove the trade-off delay-residual error after retransmissionsand makes ARQ techniques a feasible solution for error control insatellite links. Furthermore, mobility management issues inpresence of satellite diversity are addressed. Performance of anInter-Segment Hand-Over (ISHO) procedure, in terms of propagationdelay, will be carried out through simulation for different spacesegment configurations.     

卫星通信与5G融合系统发展探究

5G具有先进和成熟的技术,而卫星通信具有天然优势,例如灵活提供网络无线宽带回传、大广域广播多播、安全应急类通信等,是未来移动通信的重要组成部分。文章分析了5G和卫星通信发展情况,以及融合场景与核心技术,表达了对未来发展的展望,为相关人员提供参考。     

国外卫星移动通信新进展与发展趋势

在地面移动通信迅猛发展的新形势下,提供相似业务的卫星移动通信的发展动态和趋势值得关注.首先介绍了国外卫星移动通信市场发展动态,然后分别介绍了静止轨道、中轨道和低轨道三类卫星移动通信系统的最新进展,其中静止轨道卫星移动通信发展最好,中低轨道卫星移动通信系统发展相对不景气;最后探讨了卫星移动通信的发展趋势,指出通过星地集成...     

宽带卫星通信系统分析与技术展望

详细探讨了宽带卫星通信的发展概况、设计原则、问题和折衷考虑,提出了宽带卫星通信网络的结构模型以及卫星星座设计选择,讨论并分析了宽带卫星通信的若干关键技术以及发展所面临的问题,最后阐述了宽带卫星通信技术的未来发展趋势。     

Bandwidth galore?

The author gives a user's perspective on the role of satellite systems in the provision of broadband access to remote regions. BT launched a broadband satellite service to the Scottish Highlands & Islands and Northern Ireland. In principle, such systems offer an attractive solution to the problem of delivering telecommunication services to remote, low-density regions, but will the system work? Will it appeal to the small office/home office user? Will it mean less investment in other technologies? This article looks at these issues from the perspective of a telecommunications and IT consultant, based in the North West Highlands-currently using ISDN2 for connectivity to the major networks, who took part in the early trial of the new BT satellite service     

Satellite constellation of MEO and IGSO network routing with dynamic grouping

Because inter‐satellite links (ISLs) among the distributed satellite nodes can be used to support autonomous control in satellite system operation to reduce dependency on the ground stations, it becomes a popular communication paradigm for the future satellite systems. However, this introduces great technical challenges, particularly for routing protocol to support such space communication system. Facing the challenges, we present out study of routing technology in this paper tailored for satellite network of MEO (Table 1) and IGSO with ISLs in addition to satellite–ground links. The study aims to explore the routing strategies and algorithms of satellite network based on the evolution law of network topology to provide reference design for data exchange in autonomous satellite system. A comprehensive investigation, ranging from the analysis of relevant factors affecting data exchange in satellite networks to the primary application and resource constraints in designing satellite routing strategy, has been conducted. Our main contribution is to propose an on‐demand computing and caching centralized routing strategy and algorithm on the satellite network. The routing strategy and algorithm is designed for satellite network topology dynamic grouping. The route calculation for user data transmission is divided into three phases: direction estimation, direction enhancement, and congestion avoidance. The strategy and algorithm provide significant advantages of high efficiency, low complexity, and flexible configuration, by which the satellite networks can provide the features of flexible configure, efficient transferring, easy management, structural survivability, and great potential in scalability. Copyright © 2013 John Wiley & Sons, Ltd.     

基于内容分发的卫星网络

随着宽带业务的蓬勃发展,利用广播网络传送各种内容变得更为流行,卫星通信运营者面临巨大的机遇,他们可以把原有网络转变为传送大量新的强业务的多用途平台。文章阐述利用现有卫星技术和设备实现内容分发的方案,分析利用卫星网络进行内容分发的优势和要求,介绍卫星分发平台的组成和应用。     

卫星导航星地对接模型系统的设计与实现

随着GPS、GLONASS、GALILEO等导航系统的建设,各种导航定位系统的卫星功能越来越强大,其性能也越来越受到重视和关心。在卫星发射之前,如何进行卫星的测试与试验,是必须面临的问题。建立一套星地对接模型系统,模拟仿真真实地面设备的导航信号环境,与卫星进行星地对接试验,对卫星进行功能检查和性能检验,是解决这一问题的有效途径。介绍了星地对接模型系统的工作原理设计和信号的模拟要求,详细阐述了星地对接模型系统各种特征的实现途径,并对模拟信号进行了系统实现。