In order to alleviate the impact of turbulence on the performance of underwater wireless optical communication (UWOC) in real time, and achieve high-speed real-time transmission and low cost and miniaturization of equipment, a 2×2 real-time multiple-input and multiple-output (MIMO) high-speed miniaturized UWOC system based on a field-programmable gate array (FPGA) and a high-power light-emitting diode (LED) array is designed in this Letter. In terms of multiplexing gain, the imaging MIMO spatial multiplexing and high-order modulation for the first time are combined and the real-time high-speed transmission of PAM-4 signal based on the LED array light source in 12 m underwater channel at 100 Mbps rate is implemented, which effectively improves the throughput of the UWOC system with a high-power commercial LED light source. In light of diversity gain, the system employs the diversity of repeated coding scheme to receive two identical non-return-to-zero on-off keying (NRZ-OOK) signals, which can compensate the fading or flickering sublinks in real time under the bubble-like simulated turbulence condition, and has high robustness. To our knowledge, this is the first instance of a high rate and long-distance implementation of a turbulence-resistant real-time MIMO miniaturized UWOC system based on FPGA and high-power LED arrays. With spatial diversity or spatial multiplexing capabilities, its low cost, integrity, and high robustness provide the system with important practical prospects.

大气湍流引起的光强闪烁效应会导致信噪比下降，严重影响自由空间光通信的正常工作。空间分集技术能够有效克服这种影响，为抑制12.7 km城市水平信道大气湍流光强闪烁，设计了空间分集接收发射系统，并对分集接收的最大比合并、等增益合并和选择合并方案的抑制效果进行了对比，结果表明等增益合并方案工程实现简单，抑制效果明显，相比于单路信号闪烁指数可降低至40.1%。最后，根据全天闪烁指数变化反演了大气折射率结构常数变化，与PAMELA模型的模拟结果对比，趋势相符。研究结果对提高自由空间光通信质量有着重要意义。