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Ghaffari B.M. Matinfar M.D. Salehi J.A. 《Selected Areas in Communications, IEEE Journal on》2009,27(9):1676-1686
In this paper we present and investigate a digital design and implementational details of a wireless optical CDMA (OCDMA) system based on generalized optical orthogonal codes (OOCs). A detailed digital implementation analysis and transmitter/receiver architectures in the context of the above design are fully studied. We analyze various subsystems for a wireless OCDMA system including detector and receiver structure, acquisition, and tracking blocks as well as evaluating their performance in a typical wireless OCDMA communication system. By analyzing two main parts of the system, namely, chip-level detector and OCDMA receiver blocks we evaluate the performance of the overall system. Analytical and simulation results are presented to depict system performance. Results on the design and implementation of such systems in this paper indicate the viability and the importance of OOC based wireless OCDMA technology to satisfy certain applications need in a wider communication system worldwide. Finally we describe an experimental prototype where we highlight the main aspects of the implementation of the system. 相似文献
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无线局域网中的预约CDMA接入技术 总被引:3,自引:0,他引:3
在传统的无线MAC接入协议(如ALOHA,CSMA/CA,TDMA和CDMA)的基础上,重点探讨了基于码分多址的预约CDMA无线多址接入协议。该协议的在无线局域网接入时,无论在时间延迟还是吞吐量特性方面均比传统的无线接入协议有很大的改善。 相似文献
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The authors have discussed several alternatives in wireless LAN design: media choice, operating frequency, operating mode, network topology, and access method. Although each technical choice presents both advantages and disadvantages, they argue that there is a design point that provides the best fit with present and future wireless LAN user needs. Considering all factors-including robustness, regulatory considerations, and interference avoidance-using a product based on the slow frequency-hopping spread spectrum, in the 2.4 GHz ISM band, relying on a base station remote station network topology and using a TDMA-based access method is the best way to meet the needs of radio-frequency wireless LAN users. The choices are many, but slow frequency-hopping at 2.4 GHz and TDMA-based medium access control provide the best mix of cost, range, interference, and performance 相似文献
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Fiber-optic digital video multiplexing using optical CDMA 总被引:1,自引:0,他引:1
The use of laser pulsing in the form of code-division multiple access (CDMA) to multiplex a set of digital video signals over a fiber network is proposed. The laser pulsing is used to generate unique code sequence addresses which identify each source, and the video data are modulated on these sequences. Digital encoding using pulse position modulation (PPM) is proposed, having advantages that permit efficient integration of optical and electronic processing. Data recovery is achieved by optical correlation for sequence recognition, followed by standard electronic PPM decoding. The relation between key system parameters of the encoding, decoding, and optics is derived, and indicates that compressed video rates between 5 and 20 Mb/s/channel, with 25-50 channels, is possible with relatively standard hardware. Experimental breadboard results being carried out at USC on this system indicate the feasibility of the CDMA concept for fiber multiplexing 相似文献
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WLAN产品发展很快,已经成为许多笔记本电脑的标准配置,作为2001年最惹人注意的通信产品而引起广泛的关注,相应的最新标准也获得通过,为其进一步的发展注入了新的活力。本文全面介绍了WLAN的历史发展沿革,各种标准以及主要的应用场景。 相似文献
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通过了解无线局域网的组成和工作原理,分析影响安全的因素,并通过加密、认证等手段以及应用完整的安全解决方案,从而更好地做到无线局域网的安全防护. 相似文献
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无线局域网以其可移动性、布线简便、组网灵活和成本低廉的特点,在各行各业中越来越受到人们的关注和广泛的应用。在互联网高速发展的今天,无域局域网作为有线网络的补充或替代,有着极大广阔的发展前景和市场潜力。介绍了当前最流行的3种不同的IEEE 802.11扩展标准的特性。讨论了无线局域网的5种拓扑结构。对于无线局域网的安全技术也进行了讨论。 相似文献
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《中兴通讯技术》2001,(3):64
无线局域网标准 IEEE802.11是第一代无线局域网标准之一。 1990年 IEEE802标准化委员会成立 802.11无线局域网 (WLAN)标准工作组。 802.11无线局域网标准工作组任务为研究 1Mbit/s和 2Mbit/s数据速率、工作在 2.4GHz开放频段的无线设备和网络发展的全球标准,并于 1997年 6月公布了该标准。该标准定义物理层和媒体访问控制 (MAC)规范,允许无线局域网及无线设备制造商建立互操作网络设备。
IEEE 802.11标准中物理层定义了数据传输的信号特征和调制。在物理层中,定义了两种 RF传输方法和一种红外线传输方法。在该标准中, RF传输采用扩频方法,即采用了跳频扩频 (FHSS)和直接序列扩频 (DSSS)两种方法,工作在 2.4000GHz~ 2.4835GHz频段。 相似文献
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展望无线技术走近无线局域网 总被引:1,自引:0,他引:1
吴南晖 《信息技术与标准化》2002,(4):4-8
无线局域网技术(包括IEEE802.11、蓝牙技术、HomeRF等)将是新世纪无线通信领域最有良好发展前景的重大技术之一,本文着重介绍了无线局域网标准的进展,IEEE802.11、蓝牙技术、HomeRF等几种主流标准的比较,分析了无线局域网技术,市场,发展与应用前景。 相似文献
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介绍了VoIP的概念和基本原理和构架,重点论述了VoIP在WLAN的应用上面临的挑战及VoWLAN的发展前景,并且探讨了解决这些挑战的方法. 相似文献
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