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。

In the multiple-input multiple-output (MIMO) visible light communication (VLC) system, the effect of multipath can not be ignored specially at high bit rates. A modeling method for indoor multipath channel in VLC-MIMO system is proposed when there is the time dispersion at transmitter. A modeling method for indoor multipath channel in VLC-MIMO is proposed. Because the orthogonal frequency division multiplex (OFDM) can effectively resist inter-symbol-interference (ISI), the MIMO-asymmetrically clipped optical (ACO)-OFDM system is proposed by combing ACO-OFDM and MIMO techniques. The impulse response of each pair of LED and photoelectric detector（PD） is calculated by using recursive method. Then considering that the link between the centroid of LED and PD array is the equivalent line of sight (LOS) link, the multipath channel is established. The analysis results indicate that the gain of multipath channel is large and the multipath interference is weak when the PD arrays are at the center of the room, while the signal attenuation is large and the multipath interference is strong when the PD arrays are in a corner. The Monte Carlo bit-error-ratio (BER) simulation of MIMO-ACO-OFDM system are derived and modeled during both zero-forcing (ZF) and minimum mean square error (MMSE) signal detection. The BER performance degrades as the modulation order increases. When the modulation order is less than 64, the BER performance of ZF is worse than that of MMSE and the performance difference between ZF and MMSE decreases as the SNR increases. When the semi-angle at half power of LED becomes small, it has a better performance at the center of the room due to the strong beam convergence. Moreover, when the field of view (FOV) of LED becomes small, it has a better performance at the center of the room due to the decreased multipath interference, although the received power remains the same.