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Organic photovoltaics for simultaneous energy harvesting and high-speed MIMO optical wireless communications

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Light(Science & Applications) 2021年第3期10卷 379-389页

作者： Iman Tavakkolnia Lethy K.Jagadamma Rui Bian Pavlos P.Manousiadis Stefan Videv Graham A.Turnbull Ifor D.W.Samuel harald haas LiFi Research and Development Centre Department of Elearonic&Electrical EngineeringThe University of StrathclydeTechnology&Innovation Centre99 George StreetGlasgow G11RDUK Organic Semiconductor Centre SUPASchool of Physics and AstronomyUniversity of St AndrewsSt Andrews KY169SSUK pureLiFi Rosebery House9 Haymarket TerraceEdinburgh EH125EZUK

We show that organic photovoltaics(OPVs)are suitable for high-speed optical wireless data receivers that can also harvest *** addition,these OPVs are of particular interest for indoor applications,as their bandgap is larger than that of silicon,leading to better matching to the spectrum of artificial *** selecting a suitable combination of a narrow bandgap donor polymer and a nonfullerene acceptor,stable OPVs are fabricated with a power conversion efficiency of 8.8%under 1 Sun and 14%under indoor lighting *** an optical wireless communication experiment,a data rate of 363 Mb/s and a simultaneous harvested power of 10.9 mW are achieved in a 4-by-4 multipleinput multiple-output(MIMO)setup that consists of four laser diodes,each transmitting 56 mW optical power and four OPV cells on a single panel as receivers at a distance of 40 *** result is the highest reported data rate using OPVs as data receivers and energy *** finding may be relevant to future mobile communication applications because it enables enhanced wireless data communication performance while prolonging the battery life in a mobile device.

关键词： MIMO simultaneous lighting

Modulation Techniques for Li-Fi

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ZTE Communications 2016年第2期14卷 29-40页

作者： Mohamed Sufyan Islim harald haas Li-Fi Research and Development Centre Institute for Digital Communications University of Edinburgh

Modulation techniques for light fidelity （Li-Fi） are reviewed in this paper. Li-Fi is the fully networked solution for nmltiple users that combines communication and illumination simultaneously. Light emitting diodes （LEDs） are used in Li-Fi as visible light transmitters, therefore, only intensity modulated direct detected modulation techniques can be achieved. Single carrier modulation techniques are straightforward to be used in Li-Fi, however, computationally complex equalization processes are required in fre- quency selective Li-Fi channels. On the other hand, multiearrier modulation techniques offer a viable solution for Li-Fi in terms of power, spectral and computational efficiency. In particular, orthogonal frequency division multiplexing （OFDM） based modulation techniques offer a practical solution for Li-Fi, especially when direct current （DC） wander, and adaptive bit and power loading techniques are considered. Li-Fi modulation techniques need to also satisfy illumination requirements. Flickering avoidance and dimming control are considered in the variant modulation techniques presented. This paper surveys the suitable modulation techniques for Li-Fi including those which explore time, frequency and colour domains.

关键词： light fidelity (Li-Fi) optical wireless communications (OWC) visible light communication (VLC) intensity modulation and directdetection (IM/DD) orthogonal frequency division multiplexing (OFDM)

Cluster-Based Design for Two-hop Cellular Networks

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International Journal of Communications, Network and System Sciences 2008年第4期1卷 370-385页

作者： Hrishikesh VENKATARAMAN Sinan SINANOVIC harald haas 不详

Optimal resource allocation with an objective of maximizing the system capacity is an NP-hard problem in multihop cellular networks. Hence, different heuristic algorithms have been developed over the years that would improve the network system capacity. In this paper, a novel cluster-based architecture is proposed for a two-hop cellular network whereby the transmission distance between any communicating pair is restricted to half the cell radius. In this design, a given radio resource is used by two simultaneously communicating pairs in every hexagonal cell, but for only half the time slot period. The characteristic feature of this cluster-based design is that it enables a frequency reuse ratio of one. The proposed hierarchical system is analyzed and tested under realistic propagation conditions including lognormal shadowing. It has been observed that the system capacity of a cluster-based design is 2.5 times that obtained from the single-hop cellular system with no relaying. In addition, the cluster-based design achieves higher capacity compared to state-of-the-art two-hop algorithms. This is an important finding since the hierarchical cluster-based approach has fewer degrees of freedom in the selection of the routing path for the end-to-end connection. Practical routing algorithms should be able to benefit from this.

关键词： Cluster-Based Design Synchronized Resource Reuse Interference Model Spatial Protection Margin

Triple-cation perovskite solar cells for visible light communications

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Photonics Research 2020年第8期8卷 I0001-I0009页

作者： NATALIE AMICA RUI BIAN PAVLOS MANOUSIADIS LETHY KJAGADAMMA IMAN TAVAKKOLNIA harald haas GRAHAM ATURNBULL IFOR DWSAMUEL Organic Semiconductor Centre SUPASchool of Physics and AstronomySt AndrewsFife KY169SSUK LiFi Research and Development Centre Institute for Digital CommunicationsSchool of EngineeringUniversity of EdinburghEdinburgh EH93FDUK

Hybrid perovskite materials are widely researched due to their high absorptivity,inexpensive synthesis,and promise in photovoltaic *** materials are also of interest as highly sensitive *** this study,their potential for use in visible light communication is explored in a configuration that allows for simultaneous energy and data *** a triple-cation material and appropriate device design,a new record data rate for perovskite photodetectors of 56 Mbps and power conversion efficiencies above 20%under white LED illumination are *** this device design,the−3 dB bandwidth is increased by minimizing the dominating time constant of the *** correlation between the bandwidth and time constant is proved using measurements of time-resolved photoluminescence,transient photovoltage,and device resistance.

关键词： perovskite visible illumination

1 Gbps free-space deep-ultraviolet communications based on Ⅲ-nitride micro-LEDs emitting at 262 nm

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Photonics Research 2019年第7期7卷 19-25页

作者： Xiangyu He Enyuan Xie Mohamed Sufyan Islim Ardimas Andi Purwita Jonathan J.D.McKendry Erdan Gu harald haas Martin D.Dawson Institute of Photonics Department of PhysicsUniversity of StrathclydeGlasgow G11RDUK Li-Fi R&D Centre the University of EdinburghInstitute for Digital CommunicationsEdinburgh EH9 3JLUK

The low modulation bandwidth of deep-ultraviolet(UV) light sources is considered as the main reason limiting the data transmission rate of deep-UV communications. Here, we present high-bandwidth Ⅲ-nitride microlight-emitting diodes(μLEDs) emitting in the UV-C region and their applications in deep-UV communication systems. The fabricated UV-C μLEDs with 566 μm2 emission area produce an optical power of 196 μW at the 3400 A∕cm2 current density. The measured 3 dB modulation bandwidth of these μLEDs initially increases linearly with the driving current density and then saturates as 438 MHz at a current density of 71 A∕cm2, which is limited by the cutoff frequency of the commercial avalanche photodiode used for the measurement. A deep-UV communication system is further demonstrated. By using the UV-C μLED, up to 800 Mbps and 1.1 Gbps data transmission rates at bit error ratio of 3.8 × 10-3 are achieved assuming on-off keying and orthogonal frequency-division multiplexing modulation schemes, respectively.

关键词： communications Ⅲ-nitride micro-LEDs

10 Gbps wavelength division multiplexing using UV-A, UV-B, and UV-C micro-LEDs

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Photonics Research 2022年第2期10卷 516-523页

作者： Daniel M.Maclure Jonathan J.D.McKendry Mohamed Sufyan Islim Enyuan Xie Cheng Chen Xiaobin Sun Xudong Liang Xiaohui Huang Hanaa Abumarshoud Johannes Herrnsdorf Erdan Gu harald haas Martin D.Dawson Institute of Photonics Department of PhysicsSUPAUniversity of StrathclydeGlasgow G11RDUK LiFi Research and Development Centre Department of Electronic&Electrical EngineeringUniversity of StrathclydeTechnology&Innovation CentreGlasgow G11RDUK Fraunhofer Center of Applied Photonics Technology&Innovation CentreGlasgow G11RDUK Zhixin Semiconductor(Hangzhou)Co. Ltd.Hangzhou 311200China

Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV microlight-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately 1369 μm^(2)(equivalent to circular device pixels of diameter;0 μm). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.

关键词： Gbps multiplexing diodes

Towards 10 Gb/s orthogonal frequency division multiplexing-based visible light communication using a GaN violet micro-LED

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Photonics Research 2017年第2期5卷 35-43页

作者： MOHAMED SUFYAN ISLIM RICARDO X.FERREIRA XIANGYU HE ENYUAN XIE STEFAN VIDEV SHAUN VIOLA SCOTT WATSON NIKOLAOS BAMIEDAKIS RICHARD V.PENTY IAN H.WHITE ANTHONY E.KELLY ERDAN GU harald haas MARTIN D.DAWSON Li–Fi R&D Centre the University of Edinburgh Institute for Digital Communications Institute of Photonics Department of Physics University of Strathclyde Institute for Digital Communications Li–Fi R&D Centre the University of Edinburgh School of Engineering University of Glasgow Centre for Advanced Photonics and Electronics Electrical Engineering Division Department of Engineering University of Cambridge

Visible light communication(VLC)is a promising solution to the increasing demands for wireless *** nitride micro-sized light emitting diodes(micro-LEDs)are strong candidates for VLC due to their high *** violet micro-LEDs are reported in this work with electrical-to-optical bandwidths up to 655 *** orthogonal frequency division multiplexing-based VLC system with adaptive bit and energy loading is demonstrated,and a data transmission rate of 11.95 Gb/s is achieved with a violet micro-LED,when the nonlinear distortion of the micro-LED is the dominant noise source of the VLC system.A record 7.91 Gb/s data transmission rate is reported below the forward error correction threshold using a single pixel of the segmented array when all the noise sources of the VLC system are present.

关键词： Towards 10 Gb/s orthogonal frequency division multiplexing-based visible light communication using a GaN violet micro-LED VLC OFDM LEDs

Towards 6G wireless communication networks:vision, enabling technologies, and new paradigm shifts

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Science China(Information Sciences) 2021年第1期64卷 5-78页

作者： Xiaohu YOU Cheng-Xiang WANG Jie HUANG Xiqi GAO Zaichen ZHANG Mao WANG Yongming HUANG Chuan ZHANG Yanxiang JIANG Jiaheng WANG Min ZHU Bin SHENG Dongming WANG Zhiwen PAN Pengcheng ZHU Yang YANG Zening LIU Ping ZHANG Xiaofeng TAO Shaoqian LI Zhi CHEN Xinying MA Chih-Lin I Shuangfeng HAN Ke LI Chengkang PAN Zhimin ZHENG Lajos HANZO Xuemin (Sherman) SHEN Yingjie Jay GUO Zhiguo DING harald haas Wen TONG Peiying ZHU Ganghua YANG Jun WANG Erik G.LARSSON Hien Quoc NGO Wei HONG Haiming WANG Debin HOU Jixin CHEN Zhe CHEN Zhangcheng HAO Geoffrey Ye LI Rahim TAFAZOLLI Yue GAO H.Vincent POOR Gerhard P.FETTWEIS Ying-Chang LIANG National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast University Purple Mountain Laboratories Shanghai Institute of Fog Computing Technology (SHIFT) ShanghaiTech University Research Center for Network Communication Peng Cheng Laboratory State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and Telecommunications National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China (UESTC) China Mobile Research Institute School of Electronics and Computer Science University of Southampton Department of Electrical and Computer Engineering University of Waterloo Global Big Data Technologies Centre (GBDTC) University of Technology Sydney School of Electrical and Electronic Engineering The University of Manchester LiFi Research and Development Centre Institute for Digital CommunicationsSchool of EngineeringThe University of Edinburgh Huawei Technologies Canada Co. Ltd. Huawei Technologies Department of Electrical Engineering (ISY) Link?ping University Institute of Electronics Communications & Information Technology (ECIT)Queen's University Belfast State Key Laboratory of Millimeter Waves School of Information Science and EngineeringSoutheast University School of Electrical and Computer Engineering Georgia Institute of Technology 5G Innovation Centre University of Surrey Princeton University Vodafone Chair Mobile Communications Systems Technische Universit?t Dresden Center for Intelligent Networking and Communications (CINC) University of Electronic Science and Technology of China (UESTC)

The fifth generation(5G) wireless communication networks are being deployed worldwide from 2020 and more capabilities are in the process of being standardized, such as mass connectivity, ultra-reliability,and guaranteed low latency. However, 5G will not meet all requirements of the future in 2030 and beyond, and sixth generation(6G) wireless communication networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, better intelligence level and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architecture, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. Our vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle(UAV) communication networks, thus achieving a space-airground-sea integrated communication network. Second, all spectra will be fully explored to further increase data rates and connection density, including the sub-6GHz, millimeter wave(mmWave), terahertz(THz),and optical frequency bands. Third, facing the big datasets generated by the use of extremely heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of artificial intelligence(AI) and big data technologies. Fourth, network security will have to be strengthened when developing 6G networks. This article provides a comprehensive survey of recent advances and future trends in these four aspects. Clearly, 6G with additional technical requirements beyond those of 5G will enable f

关键词： 6G vision network architecture air interface and transmission technologies space-air-ground-sea integrated network all spectra artificial intelligence network security.

Will Germany move into a situation with unsecured power supply?

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Frontiers in Energy 2019年第3期13卷 551-570页

作者： harald SCHWARZ Energy Distribution and High Voltage Engineering Faculty 3Brandenburg University of TechnologyCottbus-Senftenberg 03013Germany

Together with a huge number of other countries, Germany signed the Paris Agreements in 2015 to prevent global temperature increase above 2℃. Within this agreement, all countries defined their own national contributions to CO2 reduction. Since that, it was visible that CO2 emissions in Germany decreased, but not so fast than proposed in this German nationally determined contribution to the Paris Agreement. Due to increasing traffic, CO2 emissions from this mobility sector increased and CO2 emission from German power generation is nearly constant for the past 20 years, even a renewable generation capacity of 112 GW was built up in 2017, which is much higher than the peak load of 84 GW in Germany. That is why the German National Government has implemented a commission (often called "The German Coal Commission") to propose a time line: how Germany can move out of coal-fired power stations. This "Coal Commission" started its work in the late spring of 2018 and handed over its final report with 336 pages to the government on January 26th, 2019. Within this report the following proposals were made:①Until 2022: Due to a former decision of the German Government, the actual remaining nuclear power generation capacity of about 10 GW has to be switched off in 2022. Besides, the "Coal Commission" proposed to switch off additionally in total 12.5 GW of both, hard coal and lignite-fired power plants, so that Germany should reduce its conventional generation capacity by 22.5 GW in 2022.②Until 2030: Another 13 GW of German hard coal or lignite-fired power plants should be switched off.③Until 2038:The final 17 GW of German hard coal or lignitefired power plants should be switched off until 2038 latest. Unfortunately the "Coal Commission" has not investigated the relevant technical parameter to ensure a secured electric power supply, based on German's own national resources. Because German Energy Revolution mainly is based on wind energy and photovoltaic, this paper will describe the

关键词： CO2 reduction mobility sector renewable generation coal commission secured power generation capacity reliable power supply power-to-gas power-to-heat