Over 700 MHz-3 dB Bandwidth UOWC System Based on Blue HV-LED With T-Bridge Pre-Equalizer
Over 700 MHz-3 dB Bandwidth UOWC System Based on Blue HV-LED With T-Bridge Pre-Equalizer
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DOI：
10.1109/jphot.2019.2910090
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发表时间：
2019-06-01
影响因子：
2.4
通讯作者：
Liu, Lilin
中科院分区：
文献类型：
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作者：
Zhang, Ziying;Lai, Yuanjia;Liu, Lilin
为了在原始调制带宽、输出光功率和动态摆幅之间实现良好的平衡，三个小型 GaN 基蓝色发光二极管 (LED) 单元在芯片上级联互连，形成 9 V HV-LED。提出了一种单级T桥均衡器，可将基于HV-LED的可见光通信/水下光无线通信（VLC/UOWC）系统的-3 dB带宽和-6 dB带宽分别提升到700 MHz和900 MHz以上。据我们所知，它是类似 LED 光功率水平 (120 mW) 下 VLC/UOWC 系统中最宽的带宽。在3.8 x 10(-3)的前向纠错（FEC）限制下，使用16QAM-OFDM调制方案无需复杂的算法即可在1.8米自由空间传输上获得3.4 Gb/s的数据速率，在1.2米水下信道上获得3 Gb/s的数据速率。 T 桥均衡器还将无差错调制带宽分别提高到 16QAM-OFDM 下高达 450 MHz 和 8QAM-OFDM 下高达 600 MHz。此外，所开发的HV-LED和T桥均衡器的结合赋予了调制响应较宽线性区域的优点，这将使通信系统对LED的退化和系统波动具有更大的耐受性。
To achieve a good balance among the raw modulation bandwidth, the output optical power, and the dynamic swing range, three small GaN-based blue light-emitting diode (LED) cells are cascade interconnected on chip to form a 9 V HV-LED. A single-stage T-bridge equalizer is proposed to upgrade the -3 dB bandwidth and -6 dB bandwidth of a visible light communication/underwater optical wireless communication (VLC/UOWC) system based on the HV-LED to be over 700 and 900 MHz, respectively. To the best of our knowledge, it is the widest bandwidth of a VLC/UOWC system at the similar LED optical power level (120 mW). Under the forward error correction (FEC) limit of 3.8 x 10(-3), data rates of 3.4 Gb/s over 1.8-m free-space transmission and 3 Gb/s over 1.2-m underwater channel are obtained using 16QAM-OFDM modulation scheme without complex algorithm. The T-bridge equalizer also improves the error free modulation bandwidths up to 450 MHz under 16QAM-OFDM, and up to 600 MHz under 8QAM-OFDM, respectively. Furthermore, the conjunction of the developed HV-LED and T-bridge equalizer endows the merit of a wide linear region of the modulation response, which will make the communication system be more tolerance to LED's degradation and system fluctuations.