Chen Xiao, Dai Yizhan, Tong Zhijian, Yang Xingqi, Li Xin, Song Guangbin, Zou Haiwu, Jia Bowen, Qin Sitong, Zhang Zejun, Zhao Jian, Xu Jing
Appl Opt. 2022 Jan 1;61(1):41-48. doi: 10.1364/AO.443498.
In order to reduce turbulence-induced scintillation and deal with alignment problems, a 2×2 multiple-input multiple-output (MIMO) underwater wireless optical communication (UWOC) system is proposed and experimentally demonstrated. With help of the large divergence angle of light beams and large field of view (FOV) of the detectors, the effect of high-density air bubbles is greatly eliminated. Simulation and experimental results confirm that, in most intensity-modulation/direct-detection (IM/DD) MIMO-UWOC systems, the repetition coding (RC) scheme performs better than the space-time block coding (STBC) scheme. In a 50 m swimming pool, the maximum horizontal offset can reach 97.9 cm, which is 421% and 192% higher than that of STBC multiple-input single-output (MISO) and RC-MISO/STBC-MIMO schemes, respectively. With a data rate of 233 Mbps and a transmission distance of 50 m, the large detection range can meet a variety of underwater wireless communication requirements. The experiment indicates that, when the difference in the transmission distance between the two optical signals is higher than 1 m, the bit error rate (BER) of the RC scheme increases sharply, while the BER of the STBC scheme is stable. The MIMO coding scheme needs to be selected according to the actual application environment.
为了减少湍流引起的闪烁并解决对准问题，提出并通过实验演示了一种2×2多输入多输出（MIMO）水下无线光通信（UWOC）系统。借助光束的大发散角和探测器的大视场（FOV），高密度气泡的影响被大大消除。仿真和实验结果证实，在大多数强度调制/直接检测（IM/DD）MIMO-UWOC系统中，重复编码（RC）方案的性能优于空时分组编码（STBC）方案。在50米的游泳池中，最大水平偏移可达97.9厘米，分别比STBC多输入单输出（MISO）和RC-MISO/STBC-MIMO方案高421%和192%。在数据速率为233 Mbps且传输距离为50米的情况下，大检测范围可以满足各种水下无线通信需求。实验表明，当两个光信号的传输距离差异高于1米时，RC方案的误码率（BER）急剧增加，而STBC方案的BER则保持稳定。需要根据实际应用环境选择MIMO编码方案。
