在水下无线光通信(UOWC)中,光传输可能会发生在近水面,此时水表面波扰动对通信性能的影响不可忽视。在实验室环境下搭建了近水面UOWC系统,应用风扇控制产生水表面波扰动场景,研究水表面波扰动对通信性能的影响。采用不归零开关键控(NRZ-OOK)调制,研究速率为500 Mbit/s的伪随机信号在10 m自来水信道传输过程中,输入光强和水表面波扰动对信号误码率(BER)的影响。研究表明:光信号在近水面传输时,系统的BER与输入光强的大小密切相关。水表面波扰动对通信质量影响显著,不仅与光传输链路中水表面波扰动的区域范围有关,还与水表面波扰动的深度有关,而且BER随扰动的范围和深度呈现某种特定的统计规律。该规律对近水面光链路、水-空链路及空-水链路的无线光通信系统的接收、跟踪和瞄准装置设计与优化具有一定指导意义。

In underwater optical wireless communication (UOWC), optical transmission can occur near the water surface. Therefore, the influence of water surface wave disturbance on communication performance cannot be ignored. In this study, a near-surface UOWC system is developed in a laboratory environment. The water surface wave disturbance scene is generated by fan control, and the influence of the water surface wave disturbance on the communication performance is studied. In the experiment, non-return-to-zero on-off keying (NRZ-OOK) modulation is adopted to study the influence of input light intensity and water surface wave disturbance on the bit error rate (BER) of a pseudo-random signal with a rate of 500 Mbit/s transferred in a 10 m tap water channel. The results show that the BER of the system is closely related to the input light intensity when the optical signal is transmitted near the water surface. The water surface wave disturbance has a significant impact on the quality of communication, which is related to the range of the water surface wave disturbance in the optical transmission link and also to the depth of the water surface wave disturbance. Moreover, the BER presents a certain statistical law with the range and depth of the disturbance. This statistical law has a certain guiding significance for receiving, tracking, and aiming devices of the near-water surface optical link, water-air link, and air-water link of a wireless optical communication system.