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中低轨卫星之间跨层激光链路的无缝切换直接决定了双层卫星光网络的稳定性.异步切换方法会导致网络拓扑频繁重构,而集中同步切换将造成两层间连接中断,网络运行状态失控.为此,本文提出了中低轨卫星星座激光链路的二次同步切换方法,在保证中低轨道卫星连通的基础上,可降低网络拓扑重构频率.研究了整数周期比的中轨道和低轨道卫星空间位置特性,建立了中低轨卫星星座构形二阶非球摄动模型,确定了中低轨道之间轨道周期比为3的双层卫星星座构形.按连接和切换顺序将该星座构形中跨层激光链路分为两组,以相对周期的1/4为基准,每次令其中一组同步切换,通过交替完成切换.研究结果表明,二次同步切换方法使得网络拓扑重构频率降低到链路切换频率的1/7,比集中切换方法在网络平均时延方面降低了30ms. 相似文献
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Tarik Taleb Abbas Jamalipour Nei Kato Yoshiaki Nemoto 《International Journal of Satellite Communications and Networking》2006,24(3):215-227
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. 相似文献
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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。 相似文献
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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。 相似文献
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国外卫星移动通信新进展与发展趋势 总被引:1,自引:0,他引:1
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... 相似文献
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In‐line interference mitigation techniques for spectral coexistence of GEO and NGEO satellites 下载免费PDF全文
Shree Krishna Sharma Symeon Chatzinotas Björn Ottersten 《International Journal of Satellite Communications and Networking》2016,34(1):11-39
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. 相似文献
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The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit (GEO) satellite and Inclining GeoSynchronous
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. 相似文献
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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. 相似文献
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LEO/MEO双层卫星网络层间星际链路建立策略的性能研究 总被引:1,自引:0,他引:1
从改善LEO/MEO双层卫星网络拓扑结构稳定性的角度出发,该文提出了3种基于集中重建的层间星际链路建立策略。新策略的基本思想是通过强制所有层间星际链路在相同时间进行重建来大幅减少网络拓扑的重构次数。仿真结果表明,与原有的策略相比,该文提出的策略能够以可接受的代价提高LEO/MEO双层卫星网络拓扑结构的稳定性。 相似文献
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随着低轨(LEO)通信卫星业务需求的增加,低轨卫星需要使用Ka频段进行通信。本文针对低轨卫星采用Ka频段可能与在轨的高轨卫星发生同频干扰问题,采用基于链路分离角的空域分隔方法进行干扰规避的角度间隔分析。分别从不同干扰场景、地面站分布情况来分析对干扰角度间隔的影响,并在此基础上提出该角度间隔范围内,低轨卫星需采取的干扰规避措施。 相似文献
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Due to the rapid development of space communication, satellite networks will be confronted with more complex space environment in future, which poses the important demand on the design of the survivable and efficient routing protocols. Among satellite networks, two-layered Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) satellite networks (LMSNs) have become an attractive architecture for their better communication service than single-layered satellite networks. To determine the topological dynamics of LMSN, the satellite group and group manager (SGGM) method is a prevalent strategy. However, it can not precisely capture the topological dynamics of the LEO layer, which may result in the unreliability of data transmission. Besides, most existing routing protocols based on the SGGM method will collapse once any top satellite fails. To overcome both limitations, this paper proposes a new topology control strategy for LMSNs. The proposed strategy determines the snapshot in terms of the topological change of the LEO layer, which ensures the topological consistency of routing calculation. Moreover, a new survivable routing protocol (SRP) is presented for LMSNs by combining both centralized and distributed routing strategies. The SRP can provide strong survivability under the LEO or MEO satellite failure. Besides, it can also achieve the minimum delay routing provided the MEO layer can effectively work. The performance of SRP is also evaluated by simulation and analysis. 相似文献
15.
针对低轨(LEO)大规模卫星星座系统存在电磁空间复杂且难于观测的问题,对低轨卫星星座链路特征进行研究。以Starlink和OneWeb星座为研究对象,根据低轨卫星的星座参数,获取等效全向辐射功(EIRP)值并进行可视化处理;对获取到的低轨电磁卫星数据进行分析,获取数据的衰减特性和时间、频率等的数据关系,计算星间的链路干扰以及时间上的分布特征;获取相对干扰时间的特征值以及星间数据的衰减与时频的多维特性,并分析不同场景下的干扰时间特征,从多个维度分析低轨大规模卫星星座系统间星间链路的干扰情况并进行仿真验证。实验证明了低轨大规模卫星星座系统之间的星间链路存在干扰情况,且频率越高,干扰现象越明显。 相似文献
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M. Leo M. Luglio 《International Journal of Satellite Communications and Networking》2002,20(6):417-434
To achieve a global cellular network, integration among segments offering different coverage (indoor, outdoor and global) must be pursued. Of course, the possibility to hold the call switching among different segments must be guaranteed. Hence, efficient algorithms to perform intersegment handover (ISHO) must be implemented. The paper aims at analysing some ISHO procedures developed in the frame of some European projects and other proposed in the literature, in a scenario with satellite and terrestrial segments interworking to achieve a worldwide cellular coverage. Performance evaluation will be carried out for different system configurations utilizing a dynamic satellite constellation simulator in the time domain. The impact of the distance user‐gateway on performance will be addressed. For each procedure, the execution delay and its complementary cumulative distribution have been evaluated for different constellation geometries at different distances from the gateway. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Handover management in Low Earth Orbit (LEO) satellite networks 总被引:13,自引:0,他引:13
Akyildiz Ian F. Uzunalioğlu Hüseyin Bender Michael D. 《Mobile Networks and Applications》1999,4(4):301-310
Low Earth Orbit (LEO) satellite networks will play an important role in the evolving information infrastructure. Satellites in the low earth orbits provide communication with shorter end-to-end delays and efficient frequency usage. However, some problems need to be solved before LEO satellite systems can be successfully deployed. One of these problems is the handover management. The objective of this paper is to survey the basic concepts of LEO satellite networks and the handover research. 相似文献
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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 相似文献
20.
QoS Handover Management in LEO/MEO Satellite Systems 总被引:4,自引:0,他引:4
Low Earth Orbit (LEO) satellite networks are foreseen to complement terrestrial networks in future global mobile networks.
Although space segment topology of a LEO network is characterized by periodic variations, connections of mobile stations (MSs)
to the satellite backbone network alter stochastically. As a result the quality of service delivered to users may degrade.
Different procedures have been proposed either as part of a resource allocation mechanism or as part of an end-to-end routing
protocol to manage transitions of MSs from one satellite to another (handover). All of these techniques are based on the prioritization
of requested handovers to ease network operation and therefore enhance provision of service. This paper proposes a new handover
procedure that exploits all geometric characteristics of a satellite-to-MS connection to provide an equable handover in systems
incorporating onboard processing satellites. Its performance is evaluated by simulations for a variety of satellite constellations
to prove its general applicability.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献