Zhang Li, Wang Zhaoming, Wei Zixian, Chen Chen, Wei Guodan, Fu H Y, Dong Yuhan
Opt Express. 2020 Oct 12;28(21):31796-31807. doi: 10.1364/OE.405417.
We experimentally demonstrated a high-speed multi-user green and blue laser diode based underwater optical wireless communication (UOWC) system using non-orthogonal multiple access (NOMA) with polarization multiplexing. The system affords eight users with a record sum rate of 18.75 Gbps over 2-m underwater plus 0.5-m free-space channel. The modulation bandwidths of four detachable optical paths with different wavelengths and polarization states all exceed 1.5 GHz. The results suggest that the flexible balance according to both user fairness and overall throughput/sum rate can be achieved via an appropriate power allocation strategy. The joint optimization of driving current and user assignment ensures the feasibility of providing stable high-speed UOWC for multiple users. With the proposed OFDMA-NOMA scheme, user scale expands by twice while the sum rate for single path reaches 3.2 Gbps. Finally, the BER performances of NOMA modality in turbulent underwater environment with air bubbles of different flow rates are also discussed in detail.
我们通过实验展示了一种基于高速多用户绿色和蓝色激光二极管的水下光无线通信（UOWC）系统，该系统采用非正交多址接入（NOMA）和偏振复用技术。该系统为八个用户提供了在2米水下加0.5米自由空间信道上18.75 Gbps的创纪录总速率。四条具有不同波长和偏振态的可拆卸光路的调制带宽均超过1.5 GHz。结果表明，通过适当的功率分配策略，可以实现用户公平性与整体吞吐量/总速率之间的灵活平衡。驱动电流和用户分配的联合优化确保了为多个用户提供稳定高速UOWC的可行性。采用所提出的正交频分多址接入 - 非正交多址接入（OFDMA - NOMA）方案，用户规模扩大了两倍，单路径总速率达到3.2 Gbps。最后，还详细讨论了在具有不同流速气泡的湍流水下环境中NOMA模式的误码率性能。
