COVERAGE PERFORMANCES ANALYSIS ON COMBINED-GEO-IGSO SATELLITE CONSTELLATION1

The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit (GEO) satellite and Inclining GeoSynchronons Orbit (IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of GEO and IGSO to achieve regional coverage.In order to discuss the performances of the Combined-GEO-IGSO constellation,the performances of coverage,elevation,diversity,and transmission are simulated in China and surrounding regions by Satellite Tool Kit (STK).The simulation results show that:the combined constellation can reach higher multi-satellite coverage and higher communication elevation in China and surrounding areas; the Doppler shift,delay,and propagation loss of this constellation have little impact on the system.As regional coverage constellation,the Combined-GEO-IGSO is feasible.     

IGSO在卫星移动通信中的应用研究

研究利用IGSO星座提供卫星移动通信业务所涉及到的星座覆盖性能、多普勒频移及业务支持能力等问题。研究表明,采用2颗或3颗IGSO卫星构成的星座能够对我国区域提供较好的覆盖性能(单星和多星覆盖率及平均通信仰角),而引入的多普勒频移并不大。链路计算结果表明,采用IGSO卫星能够有效解决GEO卫星在高纬度区域的低仰角问题,并能用比较小的IGSO卫星来达到非常大的GEO卫星才能实现的性能。因此,采用IGSO的区域卫星移动通信系统具有较好的技术可行性。     

SIMULATION AND ANALYSIS OF PERFORMANCE ON THE COMPASSTM ENHANCED BY GEO AND IGSO

Positioning accuracy of the Global Navigation Satellite System (GNSS) can be analyzed by Positioning Dilution Of Precision (PDOP).In order to enhance the navigating performance of Asia and the Pacific areas,this paper analyzes the next generation BeidouTM navigation satellite system (CompassTM) enhanced by Geostationary Earth Orbit (GEO) and Inclining GeoSynchronized Orbit (IGSO).As global navigation satellite system,CompassTM must be robust enough to avoid system layoff,when some nodes are not available.So,the CompassTM enhanced by GEO and IGSO constellation is proposed and analyzed its PDOP proformance,this paper shows some exciting results of performance of CompassTM enhanced by GEO and IGSO.From the simulation results,we can found that:when more than fifteen satellites are invalid,the enhanced system could be operating normally.     

Simulation and analysis of performance on the Compass™ enhanced by GEO and IGSO

Positioning accuracy of the Global Navigation Satellite System (GNSS) can be analyzed by Positioning Dilution Of Precision (PDOP). In order to enhance the navigating performance of Asia and the Pacific areas, this paper analyzes the next generation Beidou™ navigation satellite system (Compass™) enhanced by Geostationary Earth Orbit (GEO) and Inclining GeoSynchronized Orbit (IGSO). As global navigation satellite system, Compass™ must be robust enough to avoid system layoff, when some nodes are not available. So, the Compass™ enhanced by GEO and IGSO constellation is proposed and analyzed its PDOP proformance, this paper shows some exciting results of performance of Compass™ enhanced by GEO and IGSO. From the simulation results, we can found that: when more than fifteen satellites are invalid, the enhanced system could be operating normally.     

Theatre in the Sky: a ubiquitous broadband multimedia‐on‐demand service over a novel constellation composed of quasi‐geostationary satellites

To meet an ever‐growing demand for wideband multimedia services and electronic connectivity across the world, development of ubiquitous broadband multimedia systems is gaining a tremendous interest at both commercial and academic levels. Satellite networks will play an indispensable role in the deployment of such systems. A significant number of satellite communication constellations have been thus proposed using Geostationary (GEO), Medium Earth Orbit (MEO), or Low Earth Orbit (LEO) satellites. These constellations, however, either require a potential number of satellites or are unable to provide data transmission with high elevation angles. This paper proposes a new satellite constellation composed of Quasi‐GeoStationary Orbit (Quasi‐GSO) satellites. The main advantage of the constellation is in its ability to provide global coverage with a significantly small number of satellites while, at the same time, maintaining high elevation angles. Based on a combination of this Quasi‐GSO satellites constellation and terrestrial networks, the paper proposes also an architecture for building a global, large‐scale, and efficient Video‐on‐Demand (VoD) system. The entire architecture is referred to as a ‘Theatre in the Sky’. Copyright © 2006 John Wiley & Sons, Ltd.     

区域性中轨道卫星移动通信系统“时间决定”星座设计

区域性卫星移动通信系统对于发展中国家具有十分重要的意义,特别是对于中国这样幅员辽阔且在广大农村地区缺乏基本通信手段的国家.采用中轨星座是解决这一问题的有效途径.本文提出了一种用于区域性系统的中轨星座设计方法:"时间决定"星座设计.该星座可为特定地区提供性能优越的服务,它提供的服务可以是时限的,也可以是非时限的.利用这种设计方法可以为中国设计经济的卫星移动通信系统星座方案,同时这些星座方案也可为美国大陆提供优越的服务.     

Performance evaluation of an optimized intersegment handover procedure for hybrid constellation satellite systems

Satellite system architectures based on geostationary or Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) constellation suffer from their intrinsic limitations in terms of coverage or flexibility. Traffic requirements concerning broadband services are expected to be very uneven both in time and space. To match this requirement and to improve coverage an innovative satellite system architecture, composed of a LEO/MEO segment to complement a Geostationary Earth Orbit (GEO) segment, has been proposed. In this scenario, to achieve interworking and to make it possible to hold the call while switching between the two segments, efficient intersegment handover (ISHO) procedures must be identified. The paper, after introducing the classical ISHO schemes, aims at defining and analysing an ISHO procedure developed to perform handover in case of hybrid constellations based on the use of both GEO and LEO/MEO orbits. Performance evaluation will be carried out for different system configurations utilizing a dynamic satellite constellation simulator in the time domain. The execution delay and its complementary cumulative distribution have been evaluated for different constellation geometry at different distances from the gateway. Copyright © 2002 John Wiley & Sons, Ltd.     

基于分布式星群的双层星座设计

当前,陆地通信系统已无法满足日益复杂的信息需求,利用空间信息网络实现全球范围内的无缝覆盖和高效容量传输成为研究热点。现有卫星通信系统以单层星座为主,缺少高低轨卫星之间的协同。提出了一种基于分布式星群的双层星座设计,以基于分布式星群的低轨卫星作为网络架构的基础,采用星间链路实现低轨卫星之间的通信,通过高轨卫星实现中低纬度地区覆盖性能加强。仿真结果表明,所提方法在仅依靠在国内部署卫星地面站的前提下可实现全球多重覆盖。     

适用于我国的中轨TDRSS星座方案研究

基于中轨跟踪与数据中继卫星系统(MEO-TDRSS)星座方案的功能和业务特性,对4种常见星座实现的我国中轨TDRSS的覆盖特性和星际链路性能进行了仿真分析和比较。仿真结果表明,我国的中轨TDRSS宜采用具备卫星全球均匀分布特性的玫瑰星座和共地面轨迹星座。     

在多模卫星导航接收机中集成IRNSS

IRNSS(Indian Regional Navigation Satellite System)是印度独立开发的区域卫星导航系统， 由 3 颗 GEO(Geostationary Orbit)卫星和 4 颗 IGSO(Inclined Geo-synchronous Orbit)构成，目前已经发射 3 颗卫星，整个系统预计于 2015 年建成。IRNSS 建成之后将对南纬 30°至北纬 50°、东经 30°至东经 130°的区域提供准确的定位服务，集成 IRNSS 的多模卫星导航接收机将对上述区域的用户带来更好的服务。本文描述了 IRNSS 卫星星座、信号特点、调制方式，分析了 IRNSS 的 SPS 信号与其他卫星导航系统信号的差别，给出了在多模导航接收机芯片上集成 IRNSS 的方式。     

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。     

一种中高轨混合的多层卫星骨干网络架构设计

卫星骨干网络将向宽带与中继融合方向发展,为陆、海、空、天基用户提供全球骨干传输、宽带接入、全域通联等服务。该文针对全域用户通联的新需求,创新采用“卫星骨干网络/全域用户接入”模型,提出一种具有层内、层间星间链路的中高轨混合的多层卫星骨干网络架构(3GEO+3IGSO/24MEO)。对该架构的全域覆盖性计算分析,得出该多层卫星骨干网络能够实现地球表面到地球同步轨道高度(约36000 km)全域100%覆盖,并为全域用户提供多重接入能力。进一步对路径数、最少跳数、最小时延等关键网络性能指标分析比较,说明了该架构中轨卫星与高轨卫星之间存在层间星间链路的必要性。分析结果表明:该架构能够满足全域宽带接入和全球骨干传输的需求。     

基于STK的双层卫星星座设计及仿真

轨道与星座的设计是整个卫星通信系统设计的基础,合理的轨道设计与星座配置方案可以显著提高系统的整体性能。结合GEO卫星处理能力强,LEO卫星星地时延小的特点,以提供全球实时接入为目标,提出了一种由LEO卫星提供全球覆盖的GEO/LEO双层卫星网络星座设计方案。运用卫星覆盖带分析方法,确定由48颗LEO卫星完成全球覆盖。通过在STK仿真环境下进行计算机仿真验证,得到所设计的卫星星座可完成全天时全球覆盖。     

基于低轨卫星的北斗反射事件仿真分析

导航卫星反射事件的空间分布和数量是星载反射信号应用的综合评估指标之一, 北斗系统作为我国独立研发的导航系统, 与其他系统相比, 其反射事件的空间分布和数量具有独特性.针对上述问题, 通过研究北斗系统空间星座的特征, 模拟生成了完整的北斗系统空间星座, 给出了反射事件空间分布和数量的分析步骤, 利用导航卫星反射信号的基本几何关系推导了镜面反射点存在性判决条件.从机理上分析了北斗反射事件的影响因素, 在此基础上仿真分析了低轨卫星轨道高度、倾角、升交点赤经以及近地点角距对北斗系统同步地球轨道、倾斜地球轨道和中地球轨道卫星反射事件空间分布和数量的影响.结果表明:低轨卫星高度、升交点赤经只影响北斗反射事件数量, 而不影响分布, 轨道倾角对数量和分布都有显著影响, 轨道近地点角距无显著影响.最后, 总结给出了对地观测需合理设计低轨卫星轨道参数的指导性结论.       

Research on hierarchical architecture and routing of satellite constellation with IGSO‐GEO‐MEO network

In this paper, a three‐layered medium Earth orbit (MEO), geostationary Earth orbit (GEO), and inclined geosynchronous orbit (IGSO) satellite network (IGMSN) is presented. Based on the idea of time‐slot division, a novel dynamic hierarchical and distributed QoS (quality of service) routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path for IGSO/GEO/MEO hierarchical architecture constellation (BMDP‐HAC) algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of the IGMSN and HDRP is evaluated through simulations and theoretical analysis. And then, the paper further analyzes the performance of the IGMSN structure and the BMDP‐HAC algorithm with failure satellites.     

非同步卫星区域性星座设计与性能分析

非同步卫星区域性星座可以完成对特定区域的时限 (或非时限 )连续覆盖 [1 ]。本文在此基础上提出了利用该星座以存储 /转发的方式实现非实时全球数据通信的方法。首先介绍了系统的有关概念 ,然后以一个具体的星座方案为例简要说明了设计方法 ,之后重点讨论了星座支持全球数据通信的性能及其分析 ,并给出了用户所关心的主要性能参数。最后简要叙述了星座性能优化的方法。     

基于GEO中继卫星的地月空间通信组网及连通性研究

The architecture of cislunar multi-hop communication networks, which focuses on the re-quirements of lunar full-coverage and continuous cislunar communications, is presented on the basis of Geosynchronous Orbit (GEO) satellite network relays. According to the geographical distribution of the forthcoming Chinese Deep Space Measuring and Controlling Network (DSMCN ), two networking schemes are proposed and two elevation angle opti-mization models are established for locating GEO relay satellites. To analyze the dynamic connectivi-ty, a dynamic network model is constructed with re-spect to the time-varying characteristics of cislunar trunk links. The advantages of the two proposed schemes, in terms of the Connectivity Rate (CR), In-terruption Frequency (IF), and Average Length of Connecting Duration (ALCD), are corroborated by several simulations. In the case of the lunar polar orbit constellation case, the gains in the perform-ance of scheme I are observed to be 134.55% , 117. 03% , and 217. 47% compared with DSMCN for three evaluation indicators, and the gains in the per-formance of scheme II are observed to be 238.22% , 240.40% , and 572.71% . The results validate that the connectivity of GEO satellites outperforms that of earth facilities significantly and schemes based on GEO satellite relays are promising options for cislu-nar multi-hop communication networking.     

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。     

GEO与NGEO卫星频谱共存干扰抑制技术（一）

由于对低延时实时系统和宽带数据的需求日益增加,人们越来越关注如何在几个可用的频带中部署更多的近地轨道（LEO）和中地轨道（MEO）卫星。当可用的非静止轨道（NGEO,即LEO/MEO）卫星数目增多时,其与在轨的地球静止轨道（GEO）卫星频谱共存已经成为了一种必须。在这种情况下,为了使它们的频谱可以共用,探索一项技术来抑制GEO和NGEO系统间的干扰是非常关键的。更具体地说,在GEO和NGEO卫星网络共存的情况下,共线干扰可能是一个严重的问题,特别是在赤道上空。本文提供了几个关于如何在NGEO卫星链路和GEO卫星链路共存情况下频率共用的研究。除此之外,本文提出了几种认知方法来解决共线干扰,也提出了未来研究方向。     

适合中国的卫星通信组网的星座方案

针对我国地域分布的实际情况及通信业务量各时段的差异,提出适合中国的卫星无线光通信系统星座方案,利用3颗中轨卫星和16颗低轨卫星组成的通信系统能够覆盖我国区域,满足通信要求。