移动卫星通信系统及其关键技术

１　移动卫星通信概述 移动卫星通信系统特征是能向用户提供移动业务ＭＳＳ,并且利用卫星作中继站。所利用的卫星既可以是对地静止的卫星（ＧＥＯ）,又可以是对地非静止的卫星：如中轨道（ＭＥＯ）、低轨道（ＬＥＯ）和高椭圆轨道（ＨＥＯ）卫星等。可以称为卫星通信与移动通信结合的产物,既是一种提供移动业务的卫星通信系统,又是一种采用卫星作中继站的移动通信系统。 １．１移动卫星通信系统分类 移动卫星通信系统的分类可按其应用来分,也可按它们所采用的技术手段来分。按应用分,则分为海事移动卫星通信系统（ＭＭＳＳ）、航空移动卫星通信系统（ＡＭＳＳ）、陆地移动卫星通信系统（ＬＭＳＳ）。ＭＭＳＳ旨在改善海上救援工作,提高船舶使用效率和管理水平,增强海上通信业务和无线电定位能力。ＡＭＳＳ的主要用途是在飞机与地面之间为机组人员和乘客提供话音和数据通信业务。ＬＭＳＳ主要是利用卫星为行驶在陆地上的车辆提供通信。 通常人们根据卫星系统采用的技术手段和运行轨道,可分为对地静止轨道（ＧＥＯ）卫星移动通信系统和对地非静止轨道一（如低轨道ＬＥＯ、中轨道ＭＥＯ和高椭圆轨道ＨＥＯ）移动卫星通信系统）。ＧＥＯ系统采用静止卫星进行通信（如Ｉｎｍａｒｓａｔ的ＩＣＯ）...     

低轨道卫星在军事通信上的应用

近几年来，低轨道卫星（ＬＥＯ）通信在军事上应用的研究有了长足进展，本文主要介绍ＬＥＯ卫星在美军全球栅格网中的作用，ＯＲＢＣＯＭＭ系统在美军通信中的应用和ＬＥＯ光通信系统的设计和应用。     

浅谈卫星移动通信系统

结合卫星通信的特点和长处,分别以国际移动卫星组织（ＩＮＭＡＲＳＡＴ）和铱（Ｉｒｉｄｉｕｍ）系统为例详细介绍了静止轨道（ＧＥＯ）卫星移动通信系统和低轨道（ＬＥＯ）卫星移动通信系统的概况、系统组成、系统运行以及它们在我国的应用情况。     

第三代全球卫星移动通信系统在欧洲研究的进展

总结了欧盟“先进的通信技术与业务（ＡＣＴＳ）计划”在全球卫星移动通信方面研究的进展，介绍了ＩＮＳＵＲＥＤ、ＮＥＷＴＳＥＴ、ＳＥＣＯＭＳ、ＳＩＮＵＳ、ＴＯＭＡＳ工程在网络集成、空中接口、移动终端等方面取得的成果，认为卫星移动通信在未来的全球移动通信系统（ＵＭＴＳ）中占有重要的地位。     

EGNOS——-GPS和GLONASS的欧洲区域增强

欧洲正在开发的ＥＧＮＯＳ系统可为欧洲物陆、海、空用户提供ＧＰＳ和ＧＬＯＮＡＳＳ的区域增强服务。ＥＧＮＯＳ计划是欧洲卫星导航计划一个主要组成部分，它是由欧洲联盟委员会（ＣＥＵ）、欧空局（ＥＳＡ）和欧洲航空安全组织（ＥＵＲＯ ＣＯＮＴＲＯＬ）联合制定的。ＥＧＮＯＳ将提供如下的业务：基于ＧＥＯ的类ＧＰＳ测距信号（Ｒ－ＧＥＯ），用以改善ＧＰＳ定位在静地广播区域（ＧＢＡ）上接收机自主完善性监测（ＲＡＩＭ）的     

全球移动卫星通信

二十世纪８０年代以来，世界各地卫星通信迅猛发展，卫星技术日臻完善，使全球移动卫星通信得以实现。由于低轨道卫星（ＬＥＯ）投入使用，开辟了全球卫星移动通信的新领域。本文介绍有关卫星通信使用的频段、低轨道卫星的特点、低轨道与同步轨道卫星（ＧＥＯ）的比较、低轨道卫星如何实现覆盖全球并与地面联网实现全球通信等等。本文还介绍了国内外全球卫星移动通信实施的近况，可望在２０００年左右实现全球范围内的通信，使全球卫星移动通信能稳步跨入二十一世纪。     

原子滤光器可调谐特性在卫星光链路捕捉系统中应用探讨

在卫星激光通信捕捉系统中使用法拉第滤光器（ＦＡＤＯＦ）可以抑制背景辐射、展宽接收视场角减小捕捉时间．但ＦＡＤＯＦ的带宽要受到卫星间多普勒频移的制约,本文以赤道面圆形低轨道（ＬＥＯ）对同步轨道卫星（ＧＥＯ）光链路为实例,分析了ＬＥＯ轨道顶点和切点两个不同捕捉点的多普勒颇移特性．若采用切点作为捕捉点,卫星间多普勒频移较大,但频率变化量不大;若采用顶点作为捕捉点,卫星间多普勒频移值较小,但频率变化量大．对于不同情况的捕捉点,如何调整原子滤光器频移特性与之相适应,使带宽尽可能减小,是本文的研究目的．本文…     

空间激光通信

空间激光通信光纤技术已在地面上广泛应用。现在，欧洲空间局（ＥＳＡ）正在研究将该技术运用于空间光通信。利用激光将数据直接从一颗卫星发向另一颗卫星。１９９７年将首次演示这种链路。１９８６年，ＥＳＡ将发射月亮女神（Ａｒｔｅｍｉｓ）卫星测试并运用新的通信技术...     

ISDN和中继通信用的卫星通信系统DYANET—Ⅱ（下）

ＩＳＤＮ和中继通信用的卫星通信系统ＤＹＡＮＥＴ—Ⅱ（下）ＴｏｕｒＯｔｓｕ等４ＤＹＡＮＥＴ—Ⅱ的系统结构４．１网络结构ＤＹＡＮＥＴ—Ⅱ由一颗通信卫星、用户站（ＵＥＳ）、基站（ＢＥＳ）、一座控制站（ＣＥＳ）、一个卫星信道控制单元（ＳＣＵ）和一个卫星中转单...     

小LEO卫星系统的发展现状

在高速发展的信息社会里 ,高效、迅速、廉价地传输短消息是一种重要的通信需求。利用现有的地面有线或无线通信手段 ,可以方便地建立起覆盖一个城市或一个小区域的短消息通信系统。然而 ,如果这个系统要覆盖广大农村和边远地区 ,甚至全国或全球 ,考虑到经济因素 ,只依靠地面通信手段是无法实现的。小ＬＥＯ卫星系统就是基于建立一个覆盖全球准实时廉价的短消息通信系统的目的而提出的。按照卫星的轨道高度 ,卫星可分为三类 :低轨道卫星 (ＬＥＯ) ,轨道高度小于 50 0 0ｋｍ ;中轨道卫星 (ＭＥＯ) ,轨道高度介于 50 0 0ｋｍ～ 2 0 0 0 0ｋｍ ;…     

浅析地面无线数字电视广播系统建设

地面无线数字电视发展迅速,特别是随着国标的出台,地面无线数字电视的发展将迎来新一轮快速发展的时代.发展地面无线数字电视,是加速推进广播电视“村村通”工程的有效方式.首先概述了地面无线数字电视,然后介绍地面无线数字电视的优势,最后从建设需求、标准选择、系统结构和组成、信号覆盖情况等多方面,阐述新余市广播电视台的地面数字电视广播系统建设情况.     

移动通信无线覆盖均匀性分析

本文分析了移动通信系统中电波传播对覆盖均匀性的影响。通过典型路径传播损耗和移动通信系统同频干扰的分析,给出了衡量覆盖均匀性的性能指标。计算机模拟表明了覆盖均匀性与覆盖模式的关系。     

地面数字电视广播覆盖网建设的分析与思考

在加紧建设地方广播电视节目地面数字电视广播覆盖网的背景下,结合保山市地方广播电视节目地面数字电视广播覆盖网建设实例,从5个方面对整个系统进行了详细阐述.重点围绕技术方案展开探讨,总结了部分实用的技术数据、符合地方实际的成功做法.提出了下一步建设完善地方广播电视节目地面数字电视广播覆盖网的一些思路.     

Interference management for spectral coexistence in a heterogeneous satellite network

With the advent of the fifth generation of mobile radio communication by 2020, there will be many challenges such as increasing service demand with low delay in providing billions of end users called the satellite mobile users. It is expected that terrestrial communication systems will be faced with a dense network having many small cells anywhere and anytime. Therefore, there are some remote regions in the world where terrestrial systems cannot provide any services to end users. Furthermore, because of lack of spectral resources, it is very important that the spectrum is shared between satellite systems and terrestrial equipment by a suitable solution to interference management. In this paper, a heterogeneous satellite network that includes low earth orbit (LEO) satellite constellation and terrestrial equipment is proposed to provide low delay services. In this type of structure, interference management based on transmission power control between LEO satellite systems and mobile users is very important for obtaining high throughput. Moreover, in order to mitigate interference, transmission power control is shown based on noncooperative Stackelberg game under many subgames through pricing‐based algorithm and convex optimization method. Finally, the simulation results show that the performance of this study's system model will be improved through the proposed algorithm.     

Third generation mobile communication systems: overview and modelling considerations

Satellite and terrestrial cellular communication systems currently exist as two independent environments. In third generation systems these will complement each other and the cooperation between the two will allow for flexible and optimal radio resource allocation resulting in a reduction of some cost. However, the success of third generation systems will largely be dependent on their ability to provide improved quality of service over existing first and second generation systems, global coverage and an increased subscriber population. This paper reviews key features of the third generation systems, describes a teletraffic model suitable for such a multi-layer system, determines the benefits associated with a multilayer topology by studying the effect of the number of layers and the number of channels that can be supported by each layer and studies their effects on the performance parameters that determine the quality of service.     

Localization in terrestrial and underwater sensor‐based m2m communication networks: architecture,classification and challenges

Localizing machine‐type communication (MTC) devices or sensors is becoming important because of the increasing popularity of machine‐to‐machine (M2M) communication networks for location‐based applications. These include such as health monitoring, rescue operations, vehicle tracking, and wildfire monitoring. Moreover, efficient localization approaches for sensor‐based MTC devices reduce the localization error and energy consumption of MTC devices. Because sensors are used as an integral part of M2M communication networks and have achieved popularity in underwater applications, research is being conducted on sensor localization in both underwater and terrestrial M2M networks. Major challenges in designing underwater localization techniques are the lack of good radio signal propagation in underwater, sensor mobility management, and ensuring network coverage in 3D underwater M2M networks. Similarly, predicting the mobility pattern of MTC devices, trading‐off energy consumption and location accuracy pose great design challenges for terrestrial localization techniques. This article presents a comprehensive survey on the current state‐of‐the‐art research on both terrestrial and underwater localization approaches for sensor‐based MTC devices. It also classifies localization approaches based on several factors, identifies their limitations with potential solutions, and compares them. Copyright © 2015 John Wiley & Sons, Ltd.     

Control scheme for micro/macro/megacell-overlaying cellular systemincluding an LEO satellite system

A flexible radio resource management technique is proposed for multilayered cellular systems that consist of megacells using LEO satellites, and macrocell and microcell overlaid terrestrial cellular systems. In the proposed system, the radio spectra for microcell and macrocell terrestrial systems are adaptively and autonomously shared according to the traffic conditions of each microcell. Moreover, the radio resource for a satellite system is also dynamically shared by a temporarily unused satellite band. Computer simulation confirms that the proposed system can achieve high system capacity by reusing the radio resource allocated for the satellite band     

Technologies and performance for non-line-of-sight broadbandwireless access networks

This article presents emerging technologies for upcoming non-line-of-sight fixed or stationary broadband wireless access systems. We describe design trade-offs for overall maximization of the radio capacity and coverage of fixed wireless access (FWA) in multicell interference- and fading-prone environments. We characterize quantitatively the impact of key emerging radio technologies on the overall performance     

Cooperative strategies in satellite assisted emergency services

This paper deals with the cooperative strategies, which can be adopted in emergency scenarios by integrating space and terrestrial segments, and communication and localization services. First, the cooperative solutions for integrated Navigation and Communication systems are reviewed and an effective software‐defined radio implementation is described. Then, cooperative systems for broadcast and multicast communications in Incident Area Network are proposed and evaluated: in the broadcast scenario, low‐complexity relaying techniques are adopted to overcome the propagation impairments and the performance degradation; in the multicast system, radio resources management techniques for group communications are designed to allow the efficient use of scarce resources and improve connectivity and reliability of the overall system. The technical solutions have been studied and tested in the framework of the Italian National Research Project SAtellite‐assisted LocalIzation and Communication system for Emergency services [1]. Copyright © 2013 John Wiley & Sons, Ltd.     

5G广播电视演进和主要技术特点

地面无线广播电视作为广播电视最为重要的传输手段,在广播电视发展的很长一段时间内占据主导地位。随着计算机、微电子、移动通信、材料科学等技术飞速发展和人们不断提高的精神、物质、文化需求,无线广播电视技术开始探索向移动终端和个性化领域发展,广播电视与通信技术的融合已经成为全球性话题和探索研究方向。以国际通信组织3GPP为代表的通信与广播电视技术人员,从本世纪初开始了对现代广播电视传播体系的全面系统研究和探讨。本文全面介绍了3GPP广播模式的发展历程和主要技术特点,并基于我国广电兼具广播运营商和电信运营商的双重身份,指出了广电5G广播电视网建设演进路线,建议了未来中国3GPP广播电视分三阶段发展,提出了中国广播电视的核心模式:卫星组网+地面广播+基站覆盖。