共查询到19条相似文献,搜索用时 62 毫秒
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可见光通信是一项新兴基于白光LED的无线光通信技术,具有发射功率高、不占用无线电频谱、无电磁干扰、无电磁辐射和节约能源等优点,能够同时实现照明和通信的双重功能。阐述了可见光通信技术的发展动态,介绍基于白光LED的室内可见光通信系统,并对提高系统整体性能的若干关键技术进行了研究讨论,为白光LED室内可见光通信系统进一步研究提供依据。 相似文献
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为了研究室内多个白光LED构成的室内无线信道的特性,首先分析了多LED通信系统的基本构成,然后分析了光线追迹法求脉冲响应的基本原理和基本方法,提出了用简化的光线追迹法计算信道的脉冲响应,这种方法仅仅考虑三次以下的反射情况.最后,用数值仿真方法对室内信道的脉冲响应进行了研究.仿真结果表明,系统的脉冲响应以直接响应和一阶响应为主,并随接收器和发射装置的位置不同而发生变化. 相似文献
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为了研究室内可见光ID定位系统中可见光分布对定位功能实现的关系,搭建可见光通信异步ID定位系统,通过模拟仿真与实验相结合的方法,得出定位系统的定位范围和传输误码率分布。实验结果表明:利用Matlab可以近似地模拟实际模型的空间光分布,在光分布的三维分布图中找出定位系统光学边界,准确地调节定位系统的定位阈值。进一步搭建了50 cm50 cm50 cm的定位系统原型,在光学边界范围内实现无误码率的异步通信和定位功能,而在定位边界上,信号传输的误码率迅速上升,当信噪比为25 dB时,在光学边界上会出现8 cm的信号盲区,适当增加系统的信噪比,将有效降低信号盲区的大小。 相似文献
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可见光通信要同时兼顾照明和通信的双重作用,因此需要同时考虑光源布局及通信可靠性问题。为保证国际照明标准,在总LED灯珠不变的情况下,首先对光源布局进行了分析并数值计算了在同样功耗条件下3个及4个阵列布局方式的照度分布及均匀性。其次,为了提高多阵列可见光通信系统有效性及可靠性,将MIMO技术应用于VLC中,采用STBC编码数值计算了多阵列布局方式下系统可靠性。结果表明,在同样功耗条件下,4个阵列的MIMO系统照度均匀性较3个阵列提高了20.9%,当误码率为10-4时,41系统较31系统的误码性能大约可提高2 dB,42与32系统分别较41与31系统误码性能提高了6 dB与5 dB。 相似文献
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In this paper, we propose an indoor positioning system in which the visible light radiated from LEDs is used to locate the position of receiver. Compared to current indoor positioning systems using LED light, our system has the advantages of simple implementation, low cost, and high accuracy. In our system, a single photo diode receives pilot signals from LED panels on the ceiling. Then, the time differences of arrival of these pilot signals are used to estimate the position of the receiver. The system can be employed easily because it does not require embedding any ID to the pilot signal. In the paper, the estimation accuracy of the proposed system is analyzed through the simulation. The causes of estimation error are analyzed, and the estimation accuracy of the system in various conditions is shown by simulations. 相似文献
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Mohammed S.M. Gismalla Mohammad F.L. Abdullah Mussaab I. Niass Bhagwan Das Wafi A. Mabrouk 《International Journal of Communication Systems》2020,33(8)
Visible light communication (VLC) is an alternative technology to the radio frequency (RF) for different applications in the indoor and outdoor environments, it could be utilized for illumination and communication simultaneously, and it offers several advantages over contemporary RF technologies such as low power consumption, free license, large bandwidth, and being friendly to the environment. In this paper, an indoor VLC system uniformity improvement in terms of high received power, signal‐to‐noise ratio (SNR), and bit rate, with RMS delay spread reduction, is proposed. It features a novel model that utilizes a 13‐optical attocells configuration on the ceiling. Moreover, proposed model was evaluated at different semi‐angle at half power. The average received power and SNR were improved to 2.85 dBm and 75.5 dB, while achieved received power and SNR levels at the center of the room were 4.92 dBm and 79.5 dB, respectively. A minimum average RMS delay spread of 0.4749 nanoseconds is obtained, while the highest average bit rate calculated is 211 Mb/s. The proposed model provides a better communication quality and meets illumination standards requirements. 相似文献
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提出基于空时块码(STBC)调制的自适应多输入多输出正交频分复用(MIMO-OFDM)可见光通信(VLC)系统,该系统能够克服MIMO信道相关性并实现可靠通信。同时,引入功率比特分配(PBA)与OFDM相结合,以适应信道传输条件从而有效提高频谱效率。通过搭建一个22的MIMOOFDM VLC演示系统,实现了80 cm距离的传输,实验中测得的误码率始终保持在7%的前向纠错阈值3.810-3之下。实验结果表明,STBC MIMO-OFDM系统对MIMO信道相关性鲁棒,且PBA的应用能够大幅度提高数据速率。 相似文献
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Training sequence based channel estimation for indoor visible light communication system 总被引:1,自引:0,他引:1
Channel estimation is a key technology in indoor wireless visible light communications(VLCs).Using the training sequence(TS),this paper investigates the channel estimation in indoor wireless visible light communications.Based on the propagation and signal modulation characteristics of visible light,a link model for the indoor wireless visible light communications is established.Using the model,three channel estimation methods,i.e.,the correlation method,the least square(LS) method and the minimum mean square error(MMSE) method,are proposed.Moreover,the performances of the proposed three methods are evaluated by computer simulation.The results show that the performance of the correlation method is the worst,the LS method is suitable for higher signal to noise ratio(SNR),and the MMSE method obtains the best performance at the expense of highest complexity. 相似文献
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LED灯作为主要的新型照明工具,因其较高的灵敏度,可用于光通信系统中。为了研究与验证LED室内可见光语音通信系统的接收性能与传输距离,参照红外通信的信道模型,融入反射光的影响因素,在使用室内标准照明的光发射功率下,采用多径叠加网格算法,计算桌面各接收点接收信号功率等参量的分布,并设计与实现了LED可见光语音单向通信系统的收发电路。结果表明,当LED灯的发射功率大于2W、信号物理层通信速率不高于1Mbit/s的情况下,系统能够满足信号接收功率与接收信噪比的实际通信要求,并能够实现10m距离内的信号无失真解码与清晰收听。这一结果对LED可见光通信系统进一步的研究与应用有一定的价值。 相似文献
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A location-adaptive transmission scheme for indoor visible light communication (VLC) system is proposed in this paper. In this scheme, the symbol error rate (SER) of less than 10-3 should be guaranteed. And the scheme is realized by the variable multilevel pulse-position modulation (MPPM), where the transmitters adaptively adjust the number of time slots n in the MPPM symbol according to the position of the receiver. The purpose of our scheme is to achieve the best data rate in the indoor different locations. The results show that the location-adaptive transmission scheme based on the variable MPPM is superior in the indoor VLC system. 相似文献
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高精度室内可见光定位算法 总被引:3,自引:3,他引:0
针对目前室内定位算法精度不高、实现复杂等问 题,提出了一种基于白光LED的可见光室内定位方 法。首先利用由室内不同LED发出的定位参考信号到达定位终端的时间差(TDOA )的测量估计,得 到定位终端到达两个LED的传输距离之差,以此构造距离估计目标函数,然后采用有约束非 线性规划算法得到 定位终端的位置坐标,从而有效地解决了室内噪声环境中常规TDOA定位算法不收敛或误差偏大的问题。 同时,为了进一步优化定位性能,将距离信息引入加权因子中,提出了质心加权混合定位算 法。将提出的 定位算法在5m×5m×3m的空间区域中进行了仿真实验,同时考虑噪声因素的影响,结果 表明,提出的距离 估计目标函数法在信噪比(SNR)为2dB的条件下可以达到平 均5cm的定位误差,采用质心加权处理后平均定位误 差仅为3cm,有效地提高了室内定位精度和系统应用的普适性及鲁棒性。 相似文献