In recent studies, visible light communication (VLC) has been predicted to be a prospective technique in the future 6G communication systems. To suit the trend of exponentially growing connectivity, researchers have intensively studied techniques that enable multiple access (MA) in VLC systems, such as the MIMO system based on LED devices to support potential applications in the Internet of Things (IoT) or edge computing in the next-generation access network. However, their transmission rate is limited due to the intrinsic bandwidth of LED. Unfortunately, the majority of visible light laser communication (VLLC) research with beyond 10 Gb/s data rates concentrates on point-to-point links, or using discrete photodetector (PD) devices instead of an integrated array PD. In this paper, we demonstrated an integrated PD array device fabricated with a Si-substrated GaN/InGaN multiple-quantum-well (MQW) structure, which has a 4×4$4\times 4$ array of 50 μm×50 μm$50\mathrm{\mu m}\times 50\mathrm{\mu m}$ micro-PD units with a common cathode and anode. This single-integrated array successfully provides access for two different transmitters simultaneously in the experiment, implementing a 2×2$2\times 2$ MIMO-VLLC link at 405 nm. The highest data rate achieved is 13.2 Gb/s, and the corresponding net data rate (NDR) achieved is 12.27 Gb/s after deducing the FEC overhead, using 2.2 GHz bandwidth and superposed PAM signals. Furthermore, we assess the Huffman-coded coding scheme, which brings a fine-grain adjustment in access capacity and enhances the overall data throughput when the user signal power varies drastically due to distance, weather, or other challenges in the channel condition. As far as we know, this is the first demonstration of multiple visible light laser source access based on a single integrated GaN/InGaN receiver module.

中文翻译：

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基于集成并行GaN/InGaN微型光电探测器阵列模块的灵活2×2多址可见光通信系统

在最近的研究中，可见光通信（VLC）被预测为未来 6G 通信系统中的一项有前景的技术。为了适应连接呈指数级增长的趋势，研究人员深入研究了在 VLC 系统中实现多址 (MA) 的技术，例如基于 LED 器件的 MIMO 系统，以支持物联网 (IoT) 或边缘计算中的潜在应用。下一代接入网。然而，由于 LED 的固有带宽，它们的传输速率受到限制。不幸的是，大多数数据速率超过 10 Gb/s 的可见光激光通信 (VLLC) 研究都集中在点对点链路上，或者使用分立光电探测器 (PD) 设备而不是集成阵列 PD。在本文中，我们展示了一种采用硅衬底 GaN/InGaN 多量子阱 (MQW) 结构制造的集成 PD 阵列器件，该器件具有50 μm × 50 μm微型 PD 单元的4 × 4$4\times 4$阵列，具有公共阴极和阳极。这个单一集成阵列在实验中成功地同时为两个不同的发射器提供了接入，实现了405 nm 的2 × 2 MIMO-VLLC 链路。使用 2.2 GHz 带宽和叠加的 PAM 信号，实现的最高数据速率为 13.2 Gb/s，扣除 FEC 开销后实现的相应净数据速率 (NDR) 为 12.27 Gb/s。此外，我们评估了霍夫曼编码方案，当用户信号功率由于距离、天气或信道条件的其他挑战而剧烈变化时，该方案带来了接入容量的细粒度调整并提高了整体数据吞吐量。据我们所知，这是基于单个集成GaN/InGaN接收器模块的多个可见光激光源接入的首次演示。 $50\mathrm{\mu m}\times 50\mathrm{\mu m}$$2\times 2$