Silicon-Photomultiplier-Based Underwater Wireless Optical Communication Using Pulse-Amplitude Modulation
Silicon-Photomultiplier-Based Underwater Wireless Optical Communication Using Pulse-Amplitude Modulation
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DOI：
10.1109/joe.2019.2923501
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发表时间：
2020-10-01
影响因子：
4.1
通讯作者：
Hranilovic, Steve
中科院分区：
文献类型：
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作者：
Khalighi, Mohammad Ali;Akhouayri, Hassan;Hranilovic, Steve
由于海洋经济的持续增长，新兴的海事应用对高数据速率的水下无线链路有着固有的需求。在这种情况下，水下无线光通信被认为是一种有前途的中短距离数据传输技术；目前可用的技术提供的传输跨度约为100米。为了扩大传输范围，硅光电倍增管（SiPMs）最近成为一种具有高接收灵敏度和操作灵活性的光探测解决方案。在本文中，我们介绍了在Rx处使用脉冲幅度调制（PAM）和频域均衡（FDE）来提高通信速率，使其超过光电元件的带宽（BW）限制。例如，对于一个BW限制为2 MHz和2- pam传输，目标误码率（BER）为10（-4）的链路，如果数据速率高于类似的8 Mbps而没有均衡，则链路变得不可操作，而使用FDE可以获得更高的数据速率，例如，20和50 Mbps，最大范围分别为28和10米，在清晰的水域中，对于SensL MicroSB-30020 SiPM，平均传输光功率仅为0.6 W。同时，SiPM的非线性失真限制了调制顺序，从而限制了相对较短范围内的数据速率。我们还提出了PAM调制和解调的适当处理，考虑到使用SiPM时的量子噪声限制Rx。我们表明，当在Rx上不执行信道均衡时，使用非二进制PAM对于中等数据速率（比总链路BW高几MHz的符号速率）无疑是有利的。然而，当使用FDE时，只有对于非常高的数据速率（例如，符号速率比链路BW高10倍），链路频率响应具有高度的频率选择性时，非二进制PAM才变得非常有趣，性能优于2-PAM。
Emerging maritime applications arising from the continued growth of the marine economy have an inherent need for high data rate underwater wireless links. Within this context, underwater wireless optical communication is known as a promising technology for data transmission over short-to-medium ranges; the current available technology provides a transmission span of about 100 m. In view of extending the transmission range, silicon photomultipliers (SiPMs) have recently emerged as a photodetection solution offering high receiver (Rx) sensitivity together with operational flexibility. In this paper, we introduce the use of pulse-amplitude modulation (PAM) together with frequency-domain equalization (FDE) at the Rx to boost the communication rate beyond the bandwidth (BW) limitation of the optoelectronic components. For instance, for a link BW limited to 2 MHz and 2-PAM transmission with a target bit-error rate (BER) of 10(-4), the link becomes nonoperational for data rates higher than similar to 8 Mbps without equalization, whereas much higher data rates can be attained using FDE, e.g., 20 and 50 Mbps with maximum ranges of 28 and 10 m, respectively, in clear waters for the SensL MicroSB-30020 SiPM and an average transmit optical power of 0.6 W only. Meanwhile, the nonlinear distortion of the SiPM is shown to limit the modulation order and thus the data rate in relatively short ranges. We also propose appropriate processing for PAM modulation and demodulation, given the quantum-noise-limited Rx when using an SiPM. We show that the use of nonbinary PAM is undeniably advantageous for moderate data rates (symbol rate a few MHz higher than the overall link BW) when no channel equalization is performed at the Rx. However, when employing FDE, only for very high data rates (e.g., symbol rate ten times higher than the link BW), where the link frequency response becomes highly frequency selective, the nonbinary PAM becomes practically interesting, outperforming 2-PAM.