室内可见光通信多径信道建模及MIMO-ACO-OFDM系统性能分析

发布时间：2018-05-10 06:32

本文选题：光通信 + 多输入多输出　；参考：《光学学报》2016年07期

【摘要】：当通信速率较高时,室内光信号的多径效应不可忽视,当发送端存在时间弥散性时,提出一种室内可见光通信-多输入多输出(VLC-MIMO)多径衰落信道建模方法.由于光正交频分复用(OFDM)技术能有效抵抗码间干扰,故将非对称限幅光OFDM(ACO-OFDM)和MIMO相结合,建立MIMO-ACO-OFDM系统.用迭代法计算每对LED和光电探测器(PD)之间的冲激响应,连接LED和PD阵列的几何中心作为等效视线传输(LOS)信道,建立了多径信道模型.分析表明,当PD在房间中间时多径信道路径增益大,多径干扰弱;当PD在墙角时信号衰减大,多径干扰强.采用迫零(ZF)和最小均方误差(MMSE)检测,理论推导了系统误码率性能,建立了蒙特卡罗仿真模型.仿真表明,低阶调制时系统有更好的性能.当调制阶数小于64时,MMSE比ZF更有优势,随着信噪比增大两中检测方法得到的系统性能趋于相同;当LED半功率角变小时光束会聚强,PD在房间中心时性能最好,越往墙边性能越差;当PD视场角变小时,虽然在房间中心时接收功率不变,但多径干扰变弱性能变好.
[Abstract]:When the communication rate is high, the multipath effect of indoor optical signal can not be ignored. When the transmitter exists time dispersion, a multi-path fading channel modeling method for indoor visible light communication-multi-input multi-output VLC-MIMO-is proposed. Because the optical orthogonal frequency division multiplexing (OFDM) technique can effectively resist inter-symbol interference (ISI), MIMO-ACO-OFDM system is established by combining asymmetric OFDM (ACO-OFDM) with MIMO. The impulse response between each pair of LED and photodetector is calculated by iterative method. The geometric center connecting LED and PD array is used as the equivalent line of sight transmission channel, and a multipath channel model is established. The analysis shows that when PD is in the middle of the room, the path gain of the multipath channel is large and the multipath interference is weak, and when PD is in the corner of the wall, the signal attenuation is large and the multipath interference is strong. The system error rate (BER) performance is derived theoretically by using zero-forcing ZF) and minimum mean square error (MMSE) detection, and a Monte Carlo simulation model is established. Simulation results show that the system has better performance under low order modulation. When the modulation order is less than 64, MMSE has more advantages than ZF, and the system performance tends to be the same with the increase of signal-to-noise ratio (SNR), and the performance of LED is the best when the half-power angle of the light beam converges in the center of the room, and the performance becomes worse with the increase of the signal-to-noise ratio (SNR). When the PD field angle becomes smaller, the received power is constant in the center of the room, but the multipath interference becomes weaker and better.
【作者单位】：西南交通大学信息编码与传输四川省重点实验室;兰州理工大学计算机与通信学院;
【基金】：国家自然科学基金(61461026;61271245;61265003;61465007) 东南大学移动通信国家重点实验室开放研究基金(2014D13)
【分类号】：TN929.1

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