共查询到18条相似文献,搜索用时 156 毫秒
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本文首先介绍了Ka频段卫星通信雨衰产生机理及ITU-R雨衰预测模型。然后重点介绍了103°E在轨Ka卫星在我国各雨域地区(典型城市)的雨衰情况。最后联系以往Ku频段工程实施经验,总结出常用的三种Ka频段卫星通信抗雨衰补偿方法:分集技术中的业务速率分集技术、功率控制技术中的上行链路开环功率控制技术和自适应编码技术中的自适应纠错编码技术。 相似文献
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Ka频段卫星通信分集和自适应抗雨衰技术 总被引:1,自引:0,他引:1
Ka频段卫星通信的抗雨衰技术能够有效降低Ka频段的雨衰影响,提高Ka频段信号
传输质量。重点讨论了分集技术和自适应技术,综述了现有的抗雨衰技术及其之
间的联系,总结了热点研究方向,为今后抗雨衰技术的研究奠定了基础。 相似文献
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Ka频段的抗雨衰对策 总被引:4,自引:0,他引:4
Ka频段卫星通信系统具有广阔的应用前景,该文从Ka频段雨衰的特点以及卫星通信系统上下行链路的不同特点出发,提出了自适应抗雨衰对策。详细分析了自适应杭雨衰对策的实现原理及算法,分析得出:上行链路采用自适应功率控制,下行链路采用自适应纠错编码是解决ka频段的雨衰问题的有效方法。 相似文献
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随着Ka频段卫星通信产品的推广应用,降雨衰减在卫星通信系统中的影响越来越大。经典雨衰预测方法利用年固定时间百分比降雨率数据计算,在卫星通信系统设计中发挥了重要作用,但并不能用于天气对全网各节点的影响分析。随着气象科技的不断进步,小时降水量预报不断精细,使得在特定通信保障任务中评估预测各节点雨衰值成为可能。在充分介绍了经典雨衰模型ITU-R和数值天气预报的基础上,从降雨率换算、降雨率平均化、雨顶高度判定三个角度出发,提出了构建基于降水预报数据雨衰预报模型的关键问题,并指出了相关改进方法。 相似文献
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Ka频段卫星通信因其具有可提供的带宽大(3.5GHz)、通信容量大、波束窄、终端尺寸小,轨道平面内可容纳的卫星多和抗干扰能力强等优势成为未来卫星通信的必然趋势。Ka频段卫星通信面临的一个巨大挑战在于它受气象因素的影响大,这一度使研究人员认为Ka频段卫星通信是不可能实现的。降雨、闪烁、大气吸收等因素都会导致Ka频段地空链路信道质量的恶化。根据Ka频段卫星通信的特点,分析了降雨衰减的特性,提出了几种抗雨衰的办法。 相似文献
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Peeramed Chodkaveekityada Hajime Fukuchi 《International Journal of Satellite Communications and Networking》2017,35(4):281-293
The effects of rain attenuation on communication systems will become more pronounced in future satellite communication systems, especially with the planned use of the 21‐GHz band or higher‐frequency bands. Diversity techniques provide a solution to mitigate rain attenuation effects. This study proposes a time diversity technique, one such technique that is likely to demonstrate high effectiveness. To model the system, rainfall rate statistics are necessary, and reliability is improved as the amount of statistical data increases. This paper derives the cumulative distribution of the rainfall rate across Japan over 4 years using rain radar data from the automated meteorological data acquisition system and ground‐based rain radar network and evaluates the rainfall rate at 23 observation points across Japan. We carry out a performance evaluation for all locations within Japan to confirm the efficiency of the time diversity method. Finally, we propose prediction model of the time diversity gain for Japan and other significant parameter which is time correlation of rainfall rate that was found from the time diversity results for further investigation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Time diversity evaluation for attenuation mitigation method using attenuation data in Thailand and Japan
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Peeramed Chodkaveekityada Hajime Fukuchi 《International Journal of Satellite Communications and Networking》2017,35(4):295-305
In order to support future satellite broadcasting and communication in the Ka band and above, the time diversity method provides a novel attenuation mitigation technique for maintaining satellite service availability at levels between 99.9 and 99.99%. In this paper, the time diversity method is analyzed using various time delays from between 1 min and 1 h in an effort to mitigate convective rain attenuation by using various beacon signal transmission delays. For comparison purposes, receiver beacon data from Japan and Thailand are presented to highlight tropical and non‐tropical zone regional differences, and the International Telecommunications Union (ITU) R P.618‐12 standard is used for scaling up the Thaicom beacon frequencies from 12.57 and 12.59 GHz in the Ku band to 19.45 GHz, which is the Ka band frequency used by Japan's communication satellite (CS) beacon. We found that the time diversity method is very useful for mitigating the effects of rain attenuation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Kanellopoulos J.D. Kritikos T.D. Panagopoulos A.D. 《Antennas and Propagation, IEEE Transactions on》2007,55(7):2043-2055
The design of reliable, modern satellite communication networks, in which both frequency and orbital congestion are increasing, requires modeling of interference effects. The dominant sources of aggravation of nominal interference due to propagation phenomena are assumed to be differential rain attenuation from an adjacent satellite communication network operating at the same frequency and cross polarization due to rain and ice-crystals. A physical methodology to predict the statistics of the carrier-to-noise-plus-total-interference (CNIDR), which has already been applied to single and double-site systems, is extended to include triple-site diversity reception schemes. This method is based on a model of convective raincells model and the lognormal assumption for both the point rainfall statistics and slant path rain attenuation. The statistical properties of spatial inhomogeneity of rain attenuation over six satellite slant paths is firstly here presented. A set of simple, approximate formulas are presented which follow from a regression analysis on the previous theoretical results. The results serve to examine the influence of various parameters upon the total availability performance. 相似文献
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The propagation of high frequency electromagnetic waves through rain is affected by absorption and scattering, which both lead to signal attenuation on satellite or terrestrial super high frequency (SHF) and extremely high frequency (EHF) links. Many factors govern rain effects on waves propagating in the atmosphere, namely raindrop size distribution, rain cumulative distribution, water temperature, refractive index and operating frequency. A high degree of accuracy in the calculation of specific attenuation caused by rain (attenuation per km) is of importance when planning high frequency radio communication systems. Until now, the kRα expression has been widely used for such calculations. This relationship in which R (mm/h) represents the rain rate, α and k parameters determined for each frequency by interpolation, can be considered to be a compromise between the complexity and a simplified approach of the Van de Hulst relationship. In this paper, we present a new theoretical model based on physical laws and allowing the calculation of specific attenuation caused by all kinds of hydrometeor particles on high frequency electromagnetic waves. This method, which we derived from the forward scattering amplitude and the Van de Hulst relationship, is governed by wave polarization, the wave incidence angle, the radio link operating frequency, and precipitation particle size distribution in the climate of interest. Its application gives theoretical results which are in very good agreement with data gathered on terrestrial or earth–satellite links in several localities around the world. This new proposed model can be easily used and will constitute a very useful tool for evaluating satellite and terrestrial radio link performances, mainly in the future which will bring an expansion of high frequency satellite systems. © 1997 John Wiley & Sons, Ltd. 相似文献
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介绍了影响雨衰的要素以及常用的雨衰预测模型---IT U-R模型,通过IT U-R雨衰预测模型,以扬州地区为例计算了雨衰大小,并通过M atlab进行仿真,分析了海拔高度、卫星纬度以及信号频率对卫星通信系统的降雨衰减特性的影响。 相似文献
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降雨对于CAPS微小卫星终端通信的影响 总被引:2,自引:1,他引:1
中国区域卫星定位系统(CAPS)是卫星导航通信一体化的系统。当利用CAPS微小卫星终端系统进行卫星通信时,所用的天线口径极小,增益低,终端的有效全向辐射功率EIRP。较小,整个通信链路的余量较小。虽然C波段的降雨衰减远没有Ku波段大,但是相对于微小卫星终端的整个卫星通信链路来说,降雨带来的信号衰减、地球站接收天线G/T值的变化以及对卫星通信上、下行链路载噪比的影响也是不可忽视的。文章对这些影响进行了分析,并利用ITU—R给出的降雨衰减预报模式,给出了C波段的降雨衰减的计算方法及结果,并且分析了降雨对CAPS微小卫星通信系统的整个链路余量的影响。 相似文献
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