共查询到20条相似文献,搜索用时 62 毫秒
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陆地移动卫星通信系统设计中的多径衰落研究 总被引:5,自引:2,他引:3
分析和讨论了陆地移动卫星系统设计中的多径误落分布,根据Nakagami-Rice分布和实验数据提出了LMSA中的多径衰落预测新方法。经比较,该方法预测值同数据吻合较好且有合理的物理解释和较大的适用范围。 相似文献
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在移动卫星系统中,多径衰落是影响通信质量的重要因素之一。本文对目前在移动卫星中应用比较广泛的抗多径衰落技术进行了归纳与总结,并分析了四种的典型的抗衰落技术,最后给出了选择抗多径衰落技术方案的一般性原则。 相似文献
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移动卫星通信信道研究 总被引:2,自引:0,他引:2
分析了移动卫星通信信道的传输特征,建立并计算机模拟了移动卫星信道的统计模型,并在此基础上,建立了理想的K用户直接扩频码分多址(DS-CDMA)收发系统,研究其下行链路的误码性能。 相似文献
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多径衰落移动无线系统中的同频道干扰预测 总被引:1,自引:1,他引:0
同频道干扰是微蜂窝结构移动通信网所要考虑的一个核心问题,要想成功地对任何一种频率再用无线系统进行规划设计,就必须很好地了解并分析研究同频道干扰对系统性能的影响。本文对具有Nakagami衰落和对数正态衰落的同频道干扰特性进行了理论分析,并提出了对微蜂窝多径衰落移动无线电系统中的同频道干扰及其影响进行预测的近似方法。 相似文献
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UHF频段卫星通信的现状与未来发展 总被引:1,自引:0,他引:1
简述了特高频频段(UHF)应用于卫星通信(SATCOM)的优点及作用;介绍了当前广泛应用于美国陆海空三军和各政府机构中的UHF卫星通信系统——特高频后续(UFO)卫星系统;陈述了美军下一代UHF卫星通信系统——移动用户目标系统(MUOS)及其关键技术;提出了一种提高UHF卫星通信系统容量的新方案。 相似文献
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在通信卫星发射前,为了验证地面设备的工作特性,本文设计了一个测试平台,模拟UHF频段信道衰落特性,并给出了衰落与多普勒环境下设备性能测试情况。 相似文献
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K波段卫星通信系统的抗衰落对策 总被引:2,自引:0,他引:2
本文概述了K波段卫星通信系统发展的优越性和巨大潜力。简单介绍了该波段卫星通信系统的衰落影响因素,提出了三各抗衰落对策,位置分集、自适应资源共享技术、自适应调制技术,并加以重点讨论。同时也分析了各种抗衰落技术的优势及存在问题。 相似文献
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Approximate Outage Analysis of Land Mobile Satellite Systems in Lognormally Shadowed Rician Channels
Hossein Samimi 《Wireless Personal Communications》2011,61(2):477-490
Among the proposed models for land mobile satellite (LMS) channels, the shadowed Rice model proposed originally by Loo, has found wide applications in different frequency bands. In Loo’s model, it is assumed that the received signal is affected by nonselective Rice fading with lognormal shadowing on the direct component only, while the diffuse scattered component has constant average power level. The resulting composite probability density function (PDF) includes an infinite-range integral and is not available in closed-form, thereby making the performance evaluation of LMS communication links in these channels cumbersome. To bypass this problem, in this paper an approximation method is developed which makes it possible to describe the envelope PDF as a sum of weighted Rice’s PDFs. Therefore, in contrast with Loo’s PDF, the proposed method leads to an easy-to-use, closed-form approximate expression for the PDF and also for the most statistical characteristics, such as cumulative distribution function and moments of the signal envelop in shadowed Rice channels. Based on the derived expressions, the performance analysis of a single receiver operating over lognormally shadowed Rice channel is investigated in terms of the outage probability. Numerically evaluated results show the good accuracy of the proposed approximation method. 相似文献
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This paper presents the results of a measurement campaign conducted in the winter of 2002 around the city of Munich in southern Germany. The primary goal was to evaluate the link performance of the land mobile satellite channel at Ku-band and to characterize the temporal behavior of the channel to help in the evaluation of different fade mitigation techniques for future mobile satellite systems that aim at employing this frequency band. To achieve this objective, first- and second-order channel statistics will be presented, the outage probability of the channel analyzed, and a Markov-chain-based narrowband channel model proposed. 相似文献
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阴影环境下陆地移动卫星信道的模型研究 总被引:3,自引:0,他引:3
陆地移动卫星信道通常用全阴影模型和部分阴影模型进行分析。本文利用全阴影模型的研究结论,就实际陆地移动卫星信道部分阴影模型的仿真问题,拟合了模型参数与卫星仰角之间的关系。通过统计特性的数值计算,验证了部分阴影模型与全阴影模型的一致性。 相似文献
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本文根据我国陆海空移动用户的需求与特点,借鉴国外经验,提出了建设UHF频段卫星移动通信系统的建议;对照已建成的C波段卫星固定通信系统,分析了其优缺点;最后深入探讨了应用中的若干技术问题。 相似文献
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Ashagrie Getnet Flattie 《中兴通讯技术(英文版)》2013,(4):47-52
A mobile satellite indoor signal is proposed to model perfor mance of cooperative communication protocols and maximal ra tio combining.Cooperative diversity can improve the reliability of satellite system and increase data speed or expand cell radi us by lessening the effects of fading.Performance is determined by measured bit error rates(BERs)in different types of coopera tive protocols and indoor systems(e.g.GSM and WCDMA net works).The effect of performance on cooperative terminals lo cated at different distances from an indoor cellular system is al so discussed.The proposed schemes provide higher signal-tonoise ratio(SNR)-around 1.6 dB and 2.6 dB gap at BER 10-2for amplify-and-forward(AF)and decode-and-forward(DF)cooperative protocols,respectively,when the cooperative termi nal is located 10 m from the WCDMA indoor system.Coopera tive protocols improve effective power utilization and,hence,improve performance and cell coverage of the mobile satellite network. 相似文献
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This paper describes the result of measurements of the correction factor for buildings around a mobile station on UHF land mobile propagation characteristics. In order to express buildings around a mobile station quantitatively, four parameters are proposed: area factor of occupied buildings(alpha) , extended-area factor of occupied buildings(alphá) , buildings volume over a sampled area(beta) and buildings volume over an extended-area(betá) . The examination was carried out for each parameter in the 400 MHz and the 800 MHz bands. Consequently, it was clear that α was a suitable parameter for buildings around a mobile station, considering the balance of prediction accuracy and the efforts required to calculate a parameter. 相似文献
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