• Title/Summary/Keyword: VLC

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A Visible Light Communication Repeater Using an LED Lamp (LED 조명등을 이용한 가시광통신 중계기)

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.25 no.3
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    • pp.189-195
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    • 2016
  • In this paper, we newly introduce a visible light communication (VLC) repeater using the LED array in an LED lamp. The LED array is used for a light source in the repeater, which radiates light both for illumination and data transmission. A VLC repeater is made by adding some electronic circuits to the LED array including a photodetector, a demodulator, and a modulator. The repeater is installed on the ceiling of a room like a conventional LED lamp, receives the VLC signal from an arbitrary transmitter, recovers data, and radiates the signal to wide area in the room. We used a carrier frequency of 100 kHz for the uplink from a transmitter to the repeater, and 500 kHz for the downlink from the repeater to a receiver. The repeater is useful for increasing the transmission path to wide area over the obstacles that may exist between VLC transmitters and receivers.

Bandwidth-Efficient Precoding Scheme with Flicker Mitigation for OFDM-Based Visible Light Communications

  • Kim, Byung Wook;Jung, Sung-Yoon
    • ETRI Journal
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    • v.37 no.4
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    • pp.677-684
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    • 2015
  • Recently, orthogonal frequency-division multiplexing (OFDM) was applied to VLC systems owing to its high rate capability. On the other hand, a real-valued unipolar OFDM signal for VLC significantly reduces bandwidth efficiency. For practical implementation, channel estimation is required for data demodulation, which causes a further decrease in spectral efficiency. In addition, the large fluctuation of an OFDM signal results in poor illumination quality, such as chromaticity changes. This paper proposes a spectrally efficient method based on a hidden-pilot-aided precoding technology for VLC with less flickering than a conventional OFDM-based method. This approach can obtain channel information without any loss of bandwidth efficiency while ensuring illumination quality by reducing the flickering effect of an OFDM-based VLC. The simulation results show that the proposed method provides a 6.4% gain in bandwidth efficiency with a 4% reduction in flicker compared to a conventional OFDM-based method.

An Indoor Broadcasting System Using Light-Emitting Diode Lamps Coupled with Power Line

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.24 no.5
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    • pp.342-347
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    • 2015
  • We introduce an indoor broadcasting system using light-emitting diode (LED) lamps coupled with a 220 V power line. Two couplers connected to the power line constitute a power line communication (PLC) link. The transmission path from an LED lamp to a photodetector forms a visible light communication (VLC) link in free space. When the LED lamp is coupled to the power line, a composite PLC-VLC link is formed, making it possible to transmit a VLC signal beyond line-of-sight. In experiments, a 4 kHz analog signal modulated with a 100 kHz carrier was sent to the power line by a PLC coupler, and LED lamps coupled to the power line detected the signal and radiated it to multiple VLC receivers in the room. This configuration is useful in expanding an indoor VLC sensor network to adjacent rooms or constructing a voice broadcasting system in a building or apartments with existing power lines.

An Indoor Positioning System for Mobile Robots Using Visible Light Communication and Fuzzy Logic (가시광 통신과 퍼지 논리를 이용한 모바일 로봇의 실내 위치 인식 시스템)

  • Kim, Jun-Young;Kim, Ji-Su;Kang, Geun-Taek;Lee, Won-Chang
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.2
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    • pp.75-82
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    • 2016
  • Visible light communication (VLC) using LED lamps is suitable for implementing an indoor positioning system in an indoor environment where the global positioning system (GPS) signal does not reach. In this paper, we present an indoor positioning system for mobile robots using a VLC beacon and fuzzy rules. This system consists of an autonomous mobile robot, VLC modules, and device application software. Fuzzy rules are applied to plan the global and local paths along which the mobile robot navigates indoors. The VLC transmitter modules are attached to the wall or the ceiling as beacons to transmit their own location information. The variable pulse position modulation (VPPM) algorithm is used to transmit data, which is a new modulation scheme for VLC providing a dimming control mechanism for flicker-free optical communication. The mobile robot has a receiver module to receive the location information while performing its mission in the environment where VLC transmitters are deployed.

Novel Gain Control Scheme of Efficient Signal Detection Technique for Multiple Access VLC Systems (다중 접속 가시광 통신을 위한 신호 검출 기법의 게인 조절)

  • Lee, Sun Yui;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.11 no.1
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    • pp.32-36
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    • 2016
  • In this paper, a transceiver of VLC (Visible Light Communication) using LED white lighting has been implemented. We analyzed differences between conventional wireless communication and VLC with high-speed data transmission in a variety of environments, and confirmed symbols which passed through a channel using QAM. In order to get a high data rate, we found some variables that should be considered essentially though experiments. In addition, we set a bandwidth and found an optimal gain according to the distance between transmitter and receiver. We analyzed proposed system model through Labview and finally showed a system performance and to efficient data transmission and detection for VLC, we apply the orthogonal sequences to VLC system.

Link Recovery Scheme Using Cooperative Communication for VLC System (VLC 시스템을 위한 협동 통신을 이용한 링크 복구 방식)

  • Le, Nam-Tuan;Choi, Sun-Woong;Jang, Yeong-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.5B
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    • pp.357-364
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    • 2012
  • In Visible Light Communication (VLC) system, with the limitation of transmission range and Field Of View (FOV), LOS (Line of Sight) link between two transceivers should be guaranteed due to the straightness of the visible-light signal. Especially for indoor applications, link recovery is an advantage method to remain the link connection because of the link failure in which caused by movement obstacle. Link recovery schemes try to keep link dynamically without re-initialing connection. This article proposes a new link recover scheme for VLC system by using cooperative communication. Our propose scheme focuses on the QoS reservation resource by GTS in IEEE 802.15.7 specification in which the requested QoS resource from client should be guarantee during the application time. With the link recovery scheme, we will try to continue the link connection as long as possible when unexpected disconnect link. The mathematical analysis and simulation results show that proposed scheme increases the overall reliability of the VLC system.

Analysis Performance of VLC System according to the Transmission Distance and Angle of Incidence (전송 거리 및 입사각에 따른 가시광 통신 시스템 성능 분석에 관한 고찰)

  • Kim, Gyun-Tak;Han, Doo-Hee;Lee, Kye-San;Lee, Kyu-Jin
    • Journal of Convergence Society for SMB
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    • v.4 no.4
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    • pp.37-42
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    • 2014
  • In this paper, we analyzed the main factors that affect the performance in Visible Light Communication (VLC) system. Generally, published papers of VLC system have been studies to focus on increased data rates, transmission distance and modulation scheme. Therefore, in order to analyze detailed environment for VLC system, we was performed to analyze the performance of a major impact on the VLC system according to communication distance and the angle of incidence. The computer simulation results show that the performance attenuation was confirmed.

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Analysis of Indoor Localization Technology for Exhibition Services and Application Method of VLC/RF Converged Localization (전시 서비스를 위한 실내 측위 기술 분석 및 VLC/RF 결합 측위 적용 방안)

  • Kim, Ki-Yun;Lee, Min-Woo;Cha, Jae-Sang
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.1
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    • pp.217-225
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    • 2015
  • Recently, as the supply of smart phone is spreading and the exhibition industries are rapidly growing, future exhibitions are evolving toward active, customized, interactive, tangible services, which can give more satisfaction to visitors. To realize this services, the indoor localization in the exhibition of visitors is very important and according to the accuracy of localization the quality of services for exhibition are also different. In this paper, state-of-the art indoor localization techniques are investigated and new localization method are proposed. To achieve this goal, future exhibition service types are proposed, which are connected with IT technology. And also, BLE(Bluetooth Low Energy) technology including comparison of specifications and representative localization technologies are analysed. Furthermore we performed comparison study and simulation between RF and VLC channels. Finally based on this, we proposed converged VLC and RF(Wi-Fi and BLE) localization technique for exhibition.

Experimental Demonstration of Micro LED-to-LED Visible Light Communications (Micro LED-to-LED 무선 가시광 통신의 실험적 증명)

  • Kwon, Dong-Yoon;Kim, Sung-Man
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.2
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    • pp.219-226
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    • 2021
  • LED-to-LED VLC is a technology that uses LEDs as both a transmitter and a receiver unlike the typical VLCs. In this paper, we experimentally demonstrate a micro LED-to-LED VLC using Micro LED. We tested all the possible VLC cases using red, yellow, green, blue, and white color LED as both a transmitter and a receiver, and measured rise time and SNR. Then we calculated channel capacity depending on the LED color sets. Our experimental results show that the best channel capacity is 125 kbps when the transmitter micro LED was blue and the receiver LED was green. We also measured BERs of VLCs using OFDM signal, and we showed a successful micro LED-to-LED VLC upto 250 kbps.

Novel Gain Control Scheme for VLC systems (VLC 시스템의 새로운 이득 제어)

  • Lee, Sun Yui;Jung, Kuk Hyun;Hwang, Yu Min;Lee, Sung Hun;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.9 no.3
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    • pp.41-46
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    • 2014
  • In this paper, a transceiver of VLC (Visible Light Communication) using LED white lighting has been implemented. We analyzed differences between conventional wireless communication and VLC with high-speed data transmission in a variety of environments, and confirmed symbols which passed through a channel using QAM. In order to get a high data rate, we found some variables that should be considered essentially though experiments. In addition, we set a bandwidth and found an optimal gain according to the distance between transmitter and receiver. We analyzed proposed system model through Labview and finally showed a system performance. The performance showed a 2Mbps QAM data rate in real visible light indoor channels.