Author Affiliations
Abstract
1 Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, People’s Republic of China
2 National Institute of LED on Silicon Substrate, Nanchang University, Nanchang 330096, People’s Republic of China
3 State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, People’s Republic of China
4 State Key Laboratory of Optical Communication Technologies and Networks, China Information Communication Technologies Group Corporation, Wuhan 430000, People’s Republic of China
5 Peng Cheng Laboratory, Shenzhen, 518055, China
High-speed visible light communication (VLC), as a cutting-edge supplementary solution in 6G to traditional radio-frequency communication, is expected to address the tension between continuously increased demand of capacity and currently limited supply of radio-frequency spectrum resource. The main driver behind the high-speed VLC is the presence of light emitting diode (LED) which not only offers energy-efficient lighting, but also provides a cost-efficient alternative to the VLC transmitter with superior modulation potential. Particularly, the InGaN/GaN LED grown on Si substrate is a promising VLC transmitter to simultaneously realize effective communication and illumination by virtue of beyond 10-Gbps communication capacity and Watt-level output optical power. In previous parameter optimization of Si-substrate LED, the superlattice interlayer (SL), especially its period number, is reported to be the key factor to improve the lighting performance by enhancing the wall-plug efficiency, but few efforts were made to investigate the influence of SLs on VLC performance. Therefore, to optimize the VLC performance of Si-substrate LEDs, we for the first time investigated the impact of the SL period number on VLC system through experiments and theoretical derivation. The results show that more SL period number is related to higher signal-to-noise ratio (SNR) via improving the wall-plug efficiency. In addition, by using Levin-Campello bit and power loading technology, we achieved a record-breaking data rate of 3.37 Gbps over 1.2-m free-space VLC link under given optimal SL period number, which, to the best of our knowledge, is the highest data rate for a Si-substrate LED-based VLC system.
Author Affiliations
Abstract
1 Key Laboratory for Information Science of Electromagnetic Waves (MoE), Department of Communication Science and Engineering, Fudan University, Shanghai 200433, China
2 National Institute of LED on Silicon Substrate, Nanchang University, Nanchang 330096, China
3 State Key Laboratory of Optical Communication Technologies and Networks, China Information Communication Technologies Group Corporation, Wuhan 430074, China
High-speed visible light communication (VLC) using light-emitting diodes (LEDs) is a potential complementary technology for beyond-5G wireless communication networks. The speed of VLC systems significantly depends on the quality of LEDs, and thus various novel LEDs with enhanced VLC performance increasingly emerge. Among them, InGaN/GaN-based LEDs on a Si-substrate are a promising LED transmitter that has enabled VLC data rates beyond 10 Gbps. The optimization on the period number of superlattice interlayer (SL), which is a stress-relief epitaxial layer in a Si-substrate LED, has been demonstrated to be an effective method to improve Si-substrate LED’s luminescence properties. However, this method to improve LED’s VLC properties is barely investigated. Hence, we for the first time experimentally studied the impact of SL period number on VLC performance. Accordingly, we designed and fabricated an integrated 4 × 4 multichromatic Si-substrate wavelength-division-multiplexing LED array chip with optimal SL period number. This chip allows up to 24.25 Gbps/1.2 m VLC transmission using eight wavelengths, which is the highest VLC data rate for an InGaN/GaN LED-based VLC system to the best of our knowledge. Additionally, a record-breaking data rate of 2.02 Gbps over a 20-m VLC link is achieved using a blue Si-substrate LED with the optimal SL period number. These results validate the effectiveness of Si-substrate LEDs for both high-speed and long-distance VLC and pave the way for Si-substrate LED design specially for high-speed VLC applications.
Photonics Research
2021, 9(8): 08001581
Author Affiliations
Abstract
1 Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, China
2 Photonics Labora-tory, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
Visible-light communication (VLC) stands as a promising component of the future communication network by providing high-capacity, low-latency, and high-security wireless communication. Superluminescent diode (SLD) is proposed as a new light emitter in the VLC system due to its properties of droop-free emission, high optical power density, and low speckle-noise. In this paper, we analyze a VLC system based on SLD, demonstrating effective implementation of carrierless amplitude and phase modulation (CAP). We create a low-complexity memory-polynomial-aided neural network (MPANN) to replace the traditional finite impulse response (FIR) post-equalization filters of CAP, leading to significant mitigation of the linear and nonlinear distortion of the VLC channel. The MPANN shows a gain in Q factor of up to 2.7 dB higher than other equalizers, and more than four times lower complexity than a standard deep neural network (DNN), hence, the proposed MPANN opens a pathway for the next generation of robust and efficient neural network equalizers in VLC. We experimentally demonstrate a proof-of-concept 2.95-Gbit/s transmission using MPANN-aided CAP with 16-quadrature amplitude modulation (16-QAM) through a 30-cm channel based on the 442-nm blue SLD emitter.
superluminescent diode visible-light communication neural network Opto-Electronic Advances
2020, 3(8): 08200009
Author Affiliations
Abstract
Academy for Engineering and Technology, Shanghai Institute for Advanced Communication and Data Science, Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, China
Visible light communication (VLC) shows great potential in Internet of Vehicle applications. A single-input multi-output VLC system for Vehicle to Everything is proposed and demonstrated. A commercial car headlight is used as transmitter. With a self-designed 2 × 2 positive-intrinsic-negative (PIN) array, four independent signals are received and equalized by deep-neural-network post-equalizers, respectively. Maximum-ratio combining brings high signal-to-noise ratio and data rate gain. The transmission data rate reaches 1.25 Gb/s at 1 m and exceeds 1 Gb/s at 4 m. To the best of our knowledge, it is the first-time demonstration of beyond 1 Gb/s employing a commercial car headlight.
visible light communication Internet of Vehicle Vehicle to Everything single-input multi-output deep neural networks maximum-ratio combining Chinese Optics Letters
2020, 18(11): 110602
复旦大学通信科学与工程系电磁波信息科学教育部重点实验室, 上海 200433
随着无线通信领域的发展,具有诸多优点的可见光通信(VLC)已经发展成为了一种具有广阔前景的通信手段。然而,可见光通信中的各种非线性效应会给其信号处理带来诸多的困难,并恶化系统的性能。机器学习在解决非线性问题方面具有很大的优势和潜力,结合机器学习算法的可见光通信技术必然具有巨大的研究价值。已有研究表明,传统的机器学习算法如K-means、DBSCAN以及支持向量机(SVM)等在预均衡、后均衡、抗系统抖动,以及相位纠正等方面均有很好的表现。而深度神经网络(DNN)则因为其强大的非线性拟合能力能够更进一步提升VLC系统的性能。对以上几种方法进行了分析和介绍,并对其在可见光通信信号处理领域的应用进行了分析与总结,希望可以为机器学习解决可见光通信方面的各种非线性问题提供参考。
光通信 机器学习 非线性效应 信号处理 神经网络 激光与光电子学进展
2020, 57(1): 010001
Author Affiliations
Abstract
Shanghai Institute for Advanced Communication and Data Science, Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, China
Underwater visible light communication (UVLC) is expected to act as an alternative candidate in next-generation underwater 5G wireless optical communications. To realize high-speed UVLC, the challenge is the absorption, scattering, and turbulence of a water medium and the nonlinear response from imperfect optoelectronic devices that can bring large attenuations and a nonlinearity penalty. Nonlinear adaptive filters are commonly used in optical communication to compensate for nonlinearity. In this paper, we compare a recursive least square (RLS)-based Volterra filter, a least mean square (LMS)-based digital polynomial filter, and an LMS-based Volterra filter in terms of performance and computational complexity in underwater visible light communication. We experimentally demonstrate 2.325 Gb/s transmission through 1.2 m of water with a commercial blue light-emitting diode. Our goal is to assist the readers in refining the motivation, structure, performance, and cost of powerful nonlinear adaptive filters in the context of future underwater visible light communication in order to tap into hitherto unexplored applications and services.
060.4510 Optical communications 070.4340 Nonlinear optical signal processing 120.2440 Filters Chinese Optics Letters
2019, 17(10): 100011
Author Affiliations
Abstract
1 Department of Communication Science and Engineering, Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, China
2 National Institute of LED on Silicon Substrate, Nanchang University, Nanchang 330096, China
Visible light communication based on light-emitting diodes (LEDs) has become a promising candidate by providing high data rates, low latency, and secure communication for underwater environments. In this paper, a self-designed common-anode GaN-based five-primary-color LED (RGBYC LED) on a Si substrate is proposed and fabricated. The design of a common anode is used to mitigate the saturation effect for a low-frequency component. Additionally, compared with commercially available LEDs that suffer from nonlinearity distortion, applying the designed LED can provide much better and broader linearity according to the measurement results. Therefore, the modulation depth and system performance can be further improved to implement a high-speed underwater visible light communication (UVLC) system. There is no nonlinearity compensation algorithm applied due to the good linearity of the proposed LED; thus, the offline digital signal processing is simplified. We experimentally demonstrate 14.81 Gbit/s 64 quadrature amplitude modulation (QAM)-discrete multitone (DMT) and 15.17 Gbit/s bit-loading-DMT transmissions through a 1.2-m-long underwater channel based on the proposed RGBYC LED with an intrasymbol frequency-domain averaging channel estimation and zero-forcing equalization. As far as we know, this is the highest data rate for an LED-based UVLC system.
Photonics Research
2019, 7(9): 09001019
