Showing papers by "Min Zhang published in 2018"

Joint atmospheric turbulence detection and adaptive demodulation technique using the CNN for the OAM-FSO communication.

Abstract: A novel joint atmospheric turbulence (AT) detection and adaptive demodulation technique based on convolutional neural network (CNN) are proposed for the OAM-based free-space optical (FSO) communication. The AT detecting accuracy (ATDA) and the adaptive demodulating accuracy (ADA) of the 4-OAM, 8-OAM, 16-OAM FSO communication systems over computer-simulated 1000-m turbulent channels with 4, 6, 10 kinds of classic ATs are investigated, respectively. Compared to previous approaches using the self-organizing mapping (SOM), deep neural network (DNN) and other CNNs, the proposed CNN achieves the highest ATDA and ADA due to the advanced multi-layer representation learning without feature extractors designed carefully by numerous experts. For the AT detection, the ATDA of CNN is near 95.2% for 6 kinds of typical ATs, in cases of both weak and strong ATs. For the adaptive demodulation of optical vortices (OV) carrying OAM modes, the ADA of CNN is about 99.8% for the 8-OAM system over the computer-simulated 1000-m free-space strong turbulent link. In addition, the effects of image resolution, iteration number, activation functions and the structure of the CNN are also studied comprehensively. The proposed technique has the potential to be embedded in charge-coupled device (CCD) cameras deployed at the receiver to improve the reliability and flexibility for the OAM-FSO communication.

Undersampled-Based Modulation Schemes for Optical Camera Communications

Abstract: Widespread use of white light-emitting diodes and ubiquitous smart devices offer the opportunity to establish VLC, which has become a hot research topic based on the growing number of publications over the last decade Camera-based VLC, namely OCC, provides many unique features when compared to a single-photodiode-based system, such as the ability to separate incident light in the spatial and color domains OCC technology represents a promising approach to utilize the benefits of VLC in beyond-5G scenarios and is one of the key technologies of the Internet of Things Establishing a long communication channel in OCC, as well as non-flickering illumination by using low-frame-rate camera detectors, requires special modulation schemes This article provides an overview of the principles of three categories of modulation schemes for OCC systems using a low-frame-rate camera detector In addition, a series of undersampled modulation schemes are proposed and discussed to achieve flicker-free OCC with higher spectral efficiency In addition, framing structures are designed to solve problems occurring in OCC systems using particular modulation schemes To evaluate the performance of these modulation schemes, measured bit error rate values are shown Finally, challenges in the implementation of OCC systems are also outlined

40 Gbps–80 GHz PSK-MDM based Ro-FSO transmission system

Abstract: Bandwidth shortage of wireless carriers is a global issue that has further led to investigating the use of millimeter wave (mm-wave) in broadband cellular communication infrastructure. Radio over free space (Ro-FSO) optical system provides seamless integration of radio and optical platforms and makes it suitable for millimeter applications. This work is focused on transmission of two phase shift key encoded independent radio channels, each carrying 20 Gbps–40 GHz data, by mode division multiplexing of two modes: Laguarre Gaussian (LG) 00 and Hermite Gaussian (HG) 01. Furthermore, the modal decomposition of both channels is reported in terms of power coupling coefficient.

Linewidth-tolerant and multi-format carrier phase estimation schemes for coherent optical m-QAM flexible transmission systems.

Abstract: Multi-format and linewidth-tolerant carrier phase estimation (CPE) is a vital part of digital signal processing (DSP) units for future elastic optical transmissions to relax the laser linewidth limitation. In this paper, an innovative CPE scheme outperforming existing CPEs in both universality and performance is presented and verified for multiple quadrature amplitude modulation (QAM) formats. Based on the technique of extended QPSK partitioning and quasi-linear approximation, accurate phase estimation is determined by calculating the intersection of two symmetric straight lines with very low complexity. Comprehensive simulation results of square 4/16/32/64-QAM not only demonstrate that the scheme can be applied to different modulation formats with a universal structure, i.e., indicate its flexibility in the format-adaptive elastic optical networks (EONs), but also show that the linewidth tolerance is greatly enhanced even in comparison with traditional BPS schemes. In addition, taking 64-QAM as an example, the computational efforts can be significantly reduced by a factor of 15.7 (or 10.3) in the form of multipliers (or adders). The slightly better OSNR performance is experimentally validated in polarization multiplexing 16GBaud 4/16-QAM systems respectively, which shows the potential application for flexible receiver-side DSP unit in EONs.

Real-Time 262-Mb/s Visible Light Communication With Digital Predistortion Waveform Shaping

Abstract: A digital predistortion waveform shaping scheme combined with a blue filter is proposed to optimize both the rise and fall times of a light-emitting diode (LED) and the optical receiver current of the signal of the real-time visible light communication (VLC) system. The proposed scheme is implemented on a field-programmable gate array (FPGA) and a digital-to-analog converter based test bed, which is flexible and reconfigurable by programming the FPGA to match different LED characteristics and varied data rates. A 262-Mb/s non-return-to-zero on-off keying modulation based real-time VLC link with a bit error rate of less than $1.0\times 10^{-6}$ is achieved over a transmission distance of 5.0 m, which uses a single white phosphorous LED with a limited power of 0.1 W.

Simultaneous channel estimation and signal detection in wireless ultraviolet communications combating inter-symbol-interference.

Abstract: One primary challenge in wireless ultraviolet communications (UVCs) is the inter-symbol-interference (ISI), which may block the detection of current informative signal, especially when channel-related characteristics are unknown In this paper, we propose a UV channel-related Bayesian scheme that can simultaneously estimate the channel characteristics and detect informative signals, which therefore can address the ISI disturbance By investigating the UV single-scattering photon model, the dynamic behaviors of the channel state information (CSI), which involve the uncertain signal and the unknown channel parameters are formulated Hence, a sequential Bayesian process is suggested to estimate the UV CSI Numerical analysis shows that the proposed scheme can obtain a promising estimation performance (ie, the relative errors are less than 4%), and gain an extra 4dB detection performance compared with imperfect maximum-likelihood sequence detection (MLSD) scheme

Colorless-Light and Tunable-Light-Source Schemes for TWDM and WDM PONs

Abstract: The passive optical network (PON) has recently emerged as the most widely deployed and successful optical access solution. Data rate demands, driven by the growing use of broadband services, are expected to increase continuously over the next few decades. TWDM PONs and WDM PONs show the most promise for emerging broadband services involving various applications. In both TWDM and WDM PONs, a colorless light source or tunable transmitter is used on the ONU side and is indispensable for low-cost and plug-and-play ONUs. This article describes the principles of different colorless- light-source schemes and the architectures of the corresponding TWDM and WDM PON systems. Also, their transmission performances are analyzed and compared. Further, four types of wavelength control methods for light sources based on tunable laser diodes are described and analyzed. The features, characteristics, and applicability of the various colorless-light and tunablelight- source schemes are analyzed and compared.

Machine Learning Enabling Traffic-Aware Dynamic Slicing for 5G Optical Transport Networks

Abstract: We demonstrate a machine-learning-based traffic-aware approach for dynamic network slicing in optical networks. Experimental results indicate that the proposed framework achieves 96% traffic prediction accuracy, 49% blocking reduction and 29% delay reduction compared with conventional solutions.

Multifunctional all-optical signal processing scheme for wavelength-division-multiplexing multicast, wavelength conversion, format conversion, and all-optical encryption using hybrid modulation format exclusive-OR gates based on four-wave mixing in highly nonlinear fiber.

Abstract: A multifunctional optical signal processing scheme for 10-Gbaud quadrature phase shift keying (QPSK) and binary phase shift keying (BPSK) signals based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF) is proposed. Wavelength-division-multiplexing (WDM) multicast, wavelength conversion, modulation format conversion, and hybrid modulation format exclusive-OR (HMF-XOR) logic gates are realized simultaneously by simulation. One-to-three WDM multicast of 20-Gbps QPSK signals are achieved paying the optical signal-to-noise ratio (OSNR) penalties <0.8 dB at the bit error rate (BER) of 10−3. The converted BPSK signals with high performance are obtained; they are generated from wavelength conversion of 10-Gbps BPSK and format conversion from 20-Gpbs QPSK. In the case of HFM-XOR logic gates, we discuss the extension application in all-optical encryption. Therefore, both theoretical analysis and simulation results are conducted to analyze the feasibility of the dual-channel all-optical encryption for QPSK and BPSK signals. The OSNR penalties of decrypted QPSK and BPSK signals at the BER of 10−3 are 1 dB and 0.7 dB, respectively. The concentrated constellations and clear eye diagrams indicate the high performance of decrypted signals.

Alarm Compression Based on Machine Learning and Association Rules Mining in Optical Networks

Abstract: A method based on machine learning and association rules mining was proposed. Experiments show that the approach is practical in alarm compression, and the performance of KNA method is better than the classical Apriori algorithm.

Simultaneous wavelength and format conversion in SDN/NFV for flexible optical network based on FWM in SOA

Abstract: We propose an all-optical wavelength and format conversion model (CM) for a dynamic data center interconnect node and coherent passive optical network (PON) optical network unit (ONU) in software-defined networking and network function virtualization system based on four-wave mixing in a semiconductor optical amplifier. Five wavelength converted DQPSK signals and two format converted DPSK signals are generated; the performances of the generated signals for two strategies of setting CM in the data center interconnect node and coherent PON ONU, which are over 10 km fiber transmission, have been verified. All of the converted signals are with a power penalty less than 2.2 dB at FEC threshold of 3.8 × 10 − 3, and the optimum bias current of SOA is 300 mA.

Intelligent Optical Spectrum Analyzer Using Support Vector Machine

Abstract: A machine learning-based intelligent optical spectrum analyzer is proposed to perform center wavelength detection and OSNR calculation for QPSK signals. The good performance and fast speed are obtained, especially for SVM, achieving the optimal accuracy (100%) and the least test time (< 0.34 s).

ADTP-based OSNR Monitoring Technique Using Convolutional Neural Network

Abstract: An ADTP-based OSNR monitoring scheme using convolutional neural network is proposed. The OSNR over a range of 15-30 dB can be estimated accurately.

Service-aware Network Slicing Supporting Delay-Sensitive Services for 5G Fronthaul

Abstract: A service-aware dynamic network slicing scheme for wavelength resource supporting delay-sensitive services in 5G fronthaul is proposed. The experiment results demonstrate that this scheme is able to effectively reduce the end-to-end delay of services.

Security Performance of LDPC and Polar Codes in UV Wireless Communications

Abstract: The growing demand for access to high-capacity wireless communication systems opens up the need for the alternative and complementary technology of optical wireless communications including ultraviolet (UV). In modern wireless communications networks the users and data security, which is extremely important in order to ensure users’ data protection and confidentiality, has become a hot topic. In this paper, we investigate security in a UV communications system by adopting two well-known coding schemes of low-density parity-check (LDPC) and polar codes (PCs). We show that the UV system with coding offers enhanced security performance compared to the un-coded system with the PCs offering a higher security level and a longer transmission span compared to the LDPC.

Fiber Link Analysis and Q-factor Estimation Using CNN on Eye-Diagram

Abstract: A joint fiber link analysis and Q-factor estimation scheme using CNN-based deep learning technique on eye-diagram is proposed. Compared with the other five machine learning algorithms, the proposed one achieves the highest accuracy.

Experimental Demonstration of Traffic-aware Load Balancing for Fronthaul Network

Abstract: We propose a traffic-aware load balancing (TALB) scheme of fronthaul network and establish a software-defined optical fronthaul network (SD-OFNet) testbed. The experimental results demonstrate that TALB scheme is able to improve network performance significantly.

Visible light application device for acquiring data by scanning light source through camera

Abstract: The embodiment of the invention provides a visible light application device for acquiring data by scanning a light source through a camera. The device comprises a short message source, an informationsending end and an information receiving end, wherein the short message source is connected to the information sending end and is used to provide short messages to represent information correspondingto different light sources; the information sending end is connected to the information receiving end, and is configured to code and modulate the short messages and send the coded and modulated shortmessages to the information receiving end in a manner of optical signals; and the information receiving end is connected to the information sending end, and is configured to perform image processing on the received optical signals and obtain the short messages through frame synchronization and decoding. The scheme of the invention can achieve the effective transmission of the short messages whiletaking into consideration the illumination.

Simultaneous Wavelength and Format Conversion in Data Center Interconnect Node for NFV/SDN Optical Network based on FWM in SOA

Abstract: We propose an all-optical wavelength and format conversion model in data center interconnect node based on FWM in an SOA. Experimental results present useful to enable interconnection between data centers for NFV/SDN flexible optical network.