共查询到17条相似文献,搜索用时 171 毫秒
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针对无人飞行器大动态运动特点,提出利用地空测控窄带扩频链路的信道估计,辅助OFDM传输方式的下行宽带链路进行信道估计的方法。基于OFDM信道估计基带模型,设计了奇偶OFDM符号分组交错导频插入方式,设计了基于窄带链路多普勒频偏、多径时延信道估计的宽带链路信道估计算法。在大多普勒与多径传输信道下对算法误码率性能进行了仿真,验证了下行宽带链路具有较强的抗大多普勒、抗多径衰落的性能。 相似文献
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光纤无线电技术是近年发展起来的一种新兴宽带传输技术,满足日益增长的用户带宽需求和灵活的移动接入。然而,由于电光转换的非线性失真和无线信道的多径衰落,接收信号会受到干扰的影响而恶化,因而需要采用均衡技术对信道响应进行补偿。文中将上行信道等效为Wiener模型,接收端均衡器首先补偿光纤信道的非线性失真,减少交扰调制失真,然后采用判决反馈结构的均衡器对无线信道的响应进行补偿减少码间干扰。仿真结果验证了该方法的有效性。 相似文献
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本文分析了多径衰落信道接收信号的特点,建立了多径传播的仿真模型,并对正交频分复用OFDM系统,分别通过AWGN高斯信道、两径瑞利衰落信道、六径瑞利衰落信道进行计算机模拟仿真,得出OFDM系统具有抗多径衰落性能的结论. 相似文献
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正交频分复用OFDM(Orthogonal Frequency Division Multiplexing)与光载无线电ROF(Radio OverFiber)技术结合为实现低成本、高速数据传输的无线网络提供了可能。但RoF链路的非线性降低了系统性能。丈中在分析Machzehnder调制器的静态模型基础上,提出用Volterra级数与冲击响应分析模型相结合模型化RoF非线性系统。在此模型基础上分析Mach-Zehnder调制器以及射频放大器非线性对OFDM信号的影响。仿真分析显示非线性会使OFDM信号频谱展宽,降低信号幅度,并且随着光调制指数的增加误差矢量,带外干扰增加。为OFDM-RoF系统的线性化处理以及系统光调制器调制指教的选择提供了理论依据。 相似文献
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The integration of orthogonal frequency division multiplexing (OFDM) and radio-over-fiber (RoF) techniques have made cost-effective and high-data-rate mobile wireless Internet networks possible, such as wireless broadband networks. This paper describes the distortion effects of OFDM signals fed via an RF amplifier integrated with an RoF link employing active and passive electroabsorption modulators (EAM) for chiefly broadband in-building network applications. First, peak-to-average power ratio was investigated for RoF links. Second, the adjacent channel power ratio, which estimates the degree of spectral re- growth due to the in-band and out-of-band interference resulting from distortion effects from nonlinear amplification, error vector magnitude, and system distortion effects, was also observed for the proposed system. In this study, we considered a combined Volterra-series and impulse response-based analytical model for WiBro systems and compared it to the observed measurements. We analyzed the different nonlinear distortion effects for OFDM signals driven via an RF amplifier that was integrated with an RoF link employing a distributed feedback laser as a transmitter and an active and passive InP EAM as a receiver. The results show significant agreement between the suggested analytical model and the measurement case. This study is unique in that it examines the distortion effects of RoF links with active and passive EAMs as an access point for OFDM-based wireless access networks. 相似文献
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A novel radio-over-fiber (ROF) system has been proposed and simulated, which is based on orthogonal frequency division multiplexing (OFDM) and asymmetrical filtering of optical carrier suppression (OCS) technique, so it can effectively suppress the fading effect caused by power periodic show that the 2.5 Gbit/s OFDM-modulated wideband wireless (SMF) successfully. variation in traditional OCS system. Simulation results signal can be transmitted over 25 km single mode fiber 相似文献
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文章提出一种新型的光载波抑制一差分相移键控(OCS-DPSK)调制格式,可以实现光载无线(RoF)系统的3个关键功能:分发下行RoF信号、产生远端本振信号和上行数据的重调制,从而实现成本最优的RoF接入网络。文章作者实验演示了基于单个单臂马赫-曾德调制器产生OCS-DPSK控调制格式的全双工RoF传输系统。 相似文献
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A Novel Scheme for Seamless Integration of ROF With Centralized Lightwave OFDM-WDM-PON System 总被引:1,自引:0,他引:1
《Lightwave Technology, Journal of》2009,27(14):2786-2791
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Yong-Duck Chung Kwang-Seong Choi Jae-Sik Sim Hyun-Kyu Yu Jeha Kim 《Lightwave Technology, Journal of》2007,25(11):3407-3412
We developed an analog optical system-on-package (SoP) transmitter for a 60-GHz-band radio-over-fiber (RoF) link. The SoP transmitter consisted of an electroabsorption modulator, radio frequency amplifiers, and a bandpass filter. The 60-GHz RoF wireless link was prepared to measure the performance of the SoP transmitter. The transmission characteristics of 64-quadrature amplitude modulation (64-QAM) data of the 60-GHz RoF wireless link, including the SoP transmitter, were investigated by measuring the error vector magnitude (EVM) and signal-to-noise ratio (SNR) with a baseband frequency. The EVM of the 60-GHz RoF wireless link was between 2.25% and 2.80%, and the SNR was between 27.36 and 29.31 dB from 140 and 770 MHz, at input baseband power of -9 dBm. The noise figure had the minimum of 8.44 dB at 500 MHz. We successfully transmitted digital community antenna television (CATV) system signals through the 60-GHz RoF wireless link, including the SoP transmitter. Digital CATV signals of 86 channels could be transmitted through the 60-GHz RoF wireless link, and the total throughput was found to be 2.61 Gb/s. 相似文献