共查询到20条相似文献,搜索用时 78 毫秒
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介绍了第三代移动通信系统的概念、业务内容,分析了CDMA技术及其存在的问题,比较了提交ITU的几种无线传输的地面系统候选技术方案之间的区别,探讨了我国发展IMT-2000应采取的对策。 相似文献
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分析了未来通信业务和通信网络的发展趋势,提出对第四代移动通信系统开展研究,对无线移动通信系统和网络的发展提出了一些看法。提出了一种未来无线移动通信系统的设想,并对其中的关键问题进行讨论。 相似文献
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本文讨论了第三代移动通信系统IMT-2000的基本构成和无线传输关键技术,分析了几种方案的参数和特性,以及实现RTT技术的具体方式。 相似文献
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文章介绍了目前两种3代移动通信系统中宽我一传输技术方案--以欧洲为代表的WQ-CDMA和以美国为代表的CDMA2000。 相似文献
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简述了现代移动通信技术的六大发展趋势:网络业务趋于数据化、分组化;网络技术的宽带化;网络技术的智能化;采用更高的频段;更有效利用频率;网络趋于融合,走向统一。为运营商和业务提供商带来新的利润增长点。 相似文献
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本文描述了IMT-2000移动通信系统的无线传输测试环境,提出了选择无线传输技术的基本原则,给出了无线传输技术进行评价的方法。 相似文献
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本文描述了IMT-2000移动通信系统中无线传输技术的基本要求,探讨了无线传输的基本构成,比较了目前的几种无线传输技术方案。 相似文献
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Giannetti Filippo Luise Marco Reggiannini Ruggero 《Wireless Personal Communications》1999,10(2):207-243
This paper intends to present a summary of the technical issues arising in the exploitation of the 60 GHz mm-wave band for mobile and personal communications. The most significant applications proposed so far are surveyed, with particular emphasis placed on recent experimentation about millimeter-wave propagation for road/railway transportation as well as indoor scenarios. As a case study, the capacity of a (micro-)cellular Code Division Multiple Access (CDMA) network in the 60-GHz band is also evaluated in detail. 相似文献
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The ultimate target of mobile communications is to afford any service for anyone anywhere at anytime. The developments for this target have been receiving close attentions during the past decade. At present, many countries and communications unions all open out their standards and productions in order to occupy the future communications market. Meanwhile, China has independently developed the 3rd generation mobile communications standard TD-SCDMA. The demands of consumers have been increas… 相似文献
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移动通信网络应用范围的不断扩展和新型业务的涌现需要有更多的特殊安全协议来保障其安全性.Yi Mu和Vijay Varadharajan提出了两种分别应用于同一服务区和不同服务区的端端保密通信协议 .本文首先分析了其不足之处,然后设计了同时适用于同一归属局和不同归属局移动用户之间进行保密通信的安全协议(分别称为域内和域间保密通信协议),最后,分析了上述协议的各项性能.与原有协议相比,本文所提出的协议不仅在安全性和其他性能上有较大改进,而且更具普遍性和统一性. 相似文献
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The forthcoming mobile communication systems are expected to provide much variety of services from high quality voice to high definition videos through high data rate wireless channels at anywhere in the world. High data rate requires broad frequency bands, and sufficient broadband can be achieved in higher frequency bands such as microwave, Ka-band and millimeter-wave. Broadband wireless channels have to be connected to broadband fixed networks such as the Internet and local area networks. The future generation systems will include not only cellular phones, but also many new types of communication systems such as broadband wireless access systems, millimeter-wave LAN, intelligent transport systems (ITS) and high altitude stratospheric platform station (HAPS) systems. The key words in the future generations of mobile communications are multimedia communications, wireless access to broadband fixed networks and seamless roaming among different systems. This article discusses the future generations mobile communication systems. 相似文献
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Willie W. Lu 《中国通信》2009,6(2):134-143
This paper relates to an advanced open mobile communication system and method of integrating the mobile communications, wireless access systems and wired communications into one common platform architecture for China's 4th generation mobile communications, supporting costeffective broadband voice, data and video services in wireless, mobile and wired environment with one single integrated mobile terminal device. The paper includes new architecture in the integrated mobile device and converged network access, and minimum modification in the existing mobile telecommunication infrastructures. This paper introduces the long-term evolution strategy for China's TDD system platform towards China's future 4G mobile communications. 相似文献
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Dr.I.S.Groves 《通信学报》1995,16(4):3-7
TheEvolutionofPersonalMobileCommunicationsDr.I.S.Groves(BTLaboratories,MartleshamHeathIpswich,IP57RE,England)Abstract:WithinE... 相似文献
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未来移动通信系统及其关键技术 总被引:8,自引:7,他引:1
文中介绍了未来移动通信系统的特点和网络架构。讨论了未来移动通信物理层的正交频分复用技术(OFDM)、多入多出系统(MIMO)、认知无线电技术、软件无线电技术以及自适应调制与编码技术等传输的关键技术以及相应的网络结构和协议。最后对未来移动通信系统的发展进行了一定的展望,即未来移动通信系统应该具有高教据率、高频谱利用率、低发射功率、灵活业务支撑能力等特点。 相似文献
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A penetration rate of portable phones became more than 50% in Japan andpeople are getting to expect new kinds of services provided by new generation systems. 3rd generation IMT-2000 commercial service is to be started in the second quarter of 2001 and 4th generation systems became new research target. This paper describes new services that will be provided by IMT-2000 systems in Japan and a concept of the 4th generation system. Major technologies for 4G systems are also presented. 相似文献
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This paper presents a picture of the mobile communications market and expected further development of systems and technologies. This is done with evaluating the market needs and reflecting these to available technology as well as technological opportunities. Despite of apparently advanced state of the technology and business, both market and technical solutions are concluded to likely experience further radical changes. The need for wireless capacity is two orders of magnitude more than what combined 2G and 3G would provide. A meaningful research objective to achieve is not in any single topic but will emerge from combining the needs of market and society with the opportunities offered by plurality of technologies. This opportunity starts form explorations aiming to a deeper understanding of the spatial propagation effects and ways to deploy them. 相似文献