共查询到19条相似文献,搜索用时 78 毫秒
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介绍了MIMO和OFDM技术,MIMO—OFDM技术是由MIMO系统与OFDM技术结合而成的。基于OFDM的MIMO系统具有逼近极限的系统容量和良好的抗衰落特性,文中全面地介绍了MIMO—OFDM技术的结构和基本工作原理。 相似文献
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与传统单载波技术相比,正交频分复用(OFDM)技术具有频谱利用率高和抗频率选择性衰落能力强等优点,是提高系统传输速率和可靠性的有效手段,并且随着对OFDM技术的研究逐渐完善和成熟,OFDM技术已经得到广泛应用。在此主要介绍了OFDM技术原理和关键技术,分析了OFDM技术的应用现状,展望了在下一代移动通信中的应用和研究方向。 相似文献
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本文通过对OFDM技术性能的分析,阐述了OFDM技术的无线系统结构和OFDM技术的优势,结合海上无线系统的实际应用情况,论述了OFDM宽带无线通信系统在海上无线系统的应用,通过分析和研究得出基于OFDM技术的无线宽带通信系统是海上无线通信系统发展的必然趋势. 相似文献
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近年来,OFDM技术应用广泛。本文阐述了OFDM技术概念、工作原理、工作特点和OFDM技术在移动数据通信中的应用。 相似文献
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基于OFDM技术的光纤通信系统融合了OFDM技术以及光纤通信的双重优点。在高速率、超长距离、大容量的光纤系统中,光OFDM可作为关键技术来应用。文中简要的概述OFDM技术,介绍了光纤通信系统的特性,探究了OFDM技术在光纤通信系统中的综合应用。 相似文献
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本文简述了OFDM(正交频分复用)技术的基本原理,给出了OFDM系统的构成及功能模块,论述了OFDM技术的主要特点,介绍了OFDM技术在宽带无线通信领域中的应用. 相似文献
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OFDM技术在4G中的应用 总被引:2,自引:0,他引:2
首先给出了正交频分复用(OFDM)技术的概念,详细叙述OFDM技术的基本原理和研究现状,阐述OFDM的关键技术及在4G中的应用,给出了4G的技术规范、技术要求和国内外对4G中关键技术的研究现状。分析表明OFDM技术在不增加带宽的情况下能提高系统容量,是4G移动通信技术中的核心技术。最后给出OFDM在今后的4G移动通信系统中的研究方向。 相似文献
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Asmaa Ibrahim Tawfik Ismail Khaled Elsayed M. Saeed Darweesh 《International Journal of Communication Systems》2019,32(16)
The Orthogonal Frequency Division Multiplexing (OFDM) has emerged as one of the promising techniques because of its robustness to multipath fading with high‐speed data transmission. Classical bipolar OFDM cannot be used in intensity modulated with direct detection (IM/DD) optical communication systems, as visible light communication (VLC), so many optical modulation techniques as asymmetrical clipped optical OFDM (ACO‐OFDM) and DC‐Clipped OFDM (DCO‐OFDM) have been investigated. In this paper, we introduce a novel optical modulation scheme that meets the optical communications requirements. The proposed odd clipping optical OFDM technique (OCO‐OFDM) is based on the Fourier transform symmetry properties in which the imaginary and odd signal is converted to odd and real valued signal. As a result of this work, the proposed OCO‐OFDM and its modified version have several benefits over ACO‐OFDM and DCO‐OFDM. By introducing a better bit error rate, with the same spectral efficiency as DCO‐OFDM and the same power efficiency as ACO‐OFDM for real valued modulation technique as Binary Phase‐Shift Keying (BPSK), and with the same spectral efficiency and power efficiency as ACO‐OFDM for complex valued modulation technique as Quadrature Phase‐Shift Keying (QPSK) and Eight Phase‐Shift Keying (8PSK). 相似文献
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多载波CDMA是OFDM和CDMA结合的综合技术,兼有OFDM和CDMA的优点,可以在无线信道中传送高速数据流,在频谱效率、频率分集、抗多径干扰等方面都能获得较大好处。首先介绍了OFDM的基本原理,给出MC-CDMA的系统模型,然后通过仿真,比较了OFDM系统和MC-CDMA系统的误码性能。结果表明,MC-CDMA系统性能优于OFDM系统,说明了OFDM和CDMA技术结合的必要性。 相似文献
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近年来,正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术得到了非常广泛的应用,而同步性能的好坏对于采用OFDM技术的系统能否正常工作有很大的影响。文章介绍了OFDM系统的一般同步流程,对几种经典的OFDM系统同步算法进行了综述,并分析了OFDM系统同步技术的发展方向。 相似文献
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Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing (OFDM) systems. To counter this problem, a new wireless transmission technology based on Zero-Padding Carrier Interferometry OFDM (ZP-CI/OFDM) is proposed. In a ZP-CI/OFDM system, transmission symbols are spread to all OFDM subcarriers via carrier interferometry codes. This reduces the Peak-to-Average Power Ratio (PAPR) that traditional OFDM suffers and also exploits frequency diversity gain. By zero-padding at the transmitter, advanced receiver technologies can be adopted for ZP-CI/OFDM so that frequency diversity gain can be further utilized and the power efficiency of the system is improved. 相似文献
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目前,基于DFT变换的OFDM高效调制方法(DFT-OFDM)已经成为无线传输领域中的重要研究热点.但是,为达到较高的业务质量,DFT-OFDM采用了插入循环前缀(CP)的办法以减少ISI,从而降低了频谱利用率.为进一步改善频谱的利用效率,本文提出一种基于复小波包(Complex Wavelet Packet)正/反变换的OFDM调制方法(CWP-OFDM),并且将其与DFT-OFDM进行比较.仿真结果表明,在GSM TU50 信道环境中,当具有更高频谱效率的情况下,CWP-OFDM可以具有与DFT-OFDM同样或更好的误码性能. 相似文献
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TIAN Qing-hua ZHANG Qi TAO Ying LIU Nai-jin XIN Xiang-jun ZHANG Li-jia XU Da-xiong 《中国邮电高校学报(英文版)》2013,20(3):37-42,77
Orthogonal frequency division multiplexing (OFDM) is attracting more attention for its capability of high speed transmission. However, the OFDM possesses an obvious shortage in its high ratio of the peak power to the average power (PAPR), which has become the main issue holding it back to be applied to the broadband satellite communication system. OFDM combined with time division multiplexing (TDM), dividing the subcarriers of OFDM into some blocks in time tune, can decrease the high PAPR of OFDM. Meanwhile, the advantages of OFDM can be preserved. In this paper, OFDM/TDM is applied to the broadband satellite communication system. This paper theoretically analyses OFDM/TDM system model as well as its restraining effect on PAPR, and proposes frequency domain multiplexing-pilot (FDM-Pilot) channel estimation algorithm. Simulation results show OFDM/TDM in broadband satellite communication system has approving performance and decreased the PAPR. 相似文献