Search query: The Transmitter of the Visible Light Communication System

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abstract: In recent years, semiconductor lighting technology, also known as green lighting, has been developed rapidly. The light emitting diode (LED) is one of the most promising solid green light sources of the twenty first century.
author_names: Nan Chi
title: The Transmitter of the Visible Light Communication System
year: 2018

abstract: The method of implementations visible light communication system and the transmitting and receiving devices, including post transmitting side data to be sent constellation modulation, maps the modulated signal to the light source corresponding to and data to be sent optical signal transmitted through; receiving end will receive the the optical signal into an electrical signal, and determines the signal constellation of modulated light source according to the received signal corresponding to the received data obtained after demodulation. In the present invention, the transmission end in accordance with the visible light source is placed constellation modulation constellation, and the data to be transmitted is a signal obtained after the modulation constellation, mapped onto constellation points corresponding to the position of light source and driving the light source, so that by an optical signal transmitted data to be sent to the receiver; the receiver terminal determines the corresponding constellation point constellation according to a modulation signal source emitting a position, to acquire data from the sender. By the process of the present invention, to achieve a visible light communication, a visible light to meet the future demand scenarios.
title: Implemented method of visible light communication system and transmitter and receiver means
year: 2013

abstract: Due to limited interference range, the advantage of visible light communication (VLC) over wireless fidelity (WiFi) lies more in the unit area transmission rate rather than the single link transmission rate. To characterize the achievable transmission rate per unit area, we consider an indoor downlink VLC network with dense attocell configuration for the transmitters with single color light emitting diode (LED) and multi color LEDs, assuming binomial distributed users. We divide each attocell into central region and boundary region, and propose the transmission protocols based on such attocell division. We optimize the LED half power angle to maximize the mean achievable transmission rate per unit area. More specifically, we investigate the rates of cell center and cell boundary users under fairness consideration for the single LED transmitter system. We characterize the mean achievable transmission rate per unit area under the white light constraints in the multiple LEDs transmitter system. The performance of the proposed transmission protocols is evaluated by numerical results.
author_names: Jiaojiao Xu

Chen Gong

Jianghua Luo

Zhengyuan Xu
title: LED Half Power Angle Optimization for Ultra Dense Indoor Visible Light Communication Network Deployment
venue: IEEE Open Journal of the Communications Society
year: 2020

abstract: A high efficiency linear assisted Visible Light Communication (VLC) LED driver working as a transmitter is presented in this work. A linear assisted transmitter is based on the idea of using a high efficiency but bandwidth limited circuitry which delivers most of the power and a low efficiency but fast linear amplifier (linear assistance) which corrects the distortion of the signal. The presented solution takes advantage of the light in a VLC system by summing the contribution of the linear amplifier in light instead of electrically, which leads to a electrical isolation between both stages and a reduction of the complexity comparing to the traditional approach used in Envelope Tracking (ET) and Envelope Elimination and Restoration (EER) techniques. As experimental results, the design of a linear assisted Class E amplifier delivering a 16 PSK phase digital modulation with a 1 MHz carrier is presented. On one hand, the Class E amplifier delivers most of the power (92% of the signal power) at high efficiency (81 and, on the other hand, the linear amplifier only delivers the error signal at lower efficiency. The efficiency of the signal circuitry is up to 75% and the efficiency of the whole system considering the signal and the LED biasing circuitry is up to 85%
author_names: Daniel Garcia Aller

Diego G Lamar

Pablo Fernandez Miaja

Juan Rodriguez

Javier Sebastian
title: Design of a Linear Assisted VLC LED Transmitter Based on Summing the Light
venue: IECON 2019 45th Annual Conference of the IEEE Industrial Electronics Society
year: 2019

abstract: The emergence of visible light communication (VLC) as a subset of optical wireless communication (OWC) in the early 2000s has turned any light emitting diode (LED) source into a potential data transmitter. The design process for any VLC or OWC system typically involves a link budget analysis performed by studying the signal to noise ratio (SNR) at the receiver. Since this SNR strongly depends on the radiant flux collected by the receiver, an accurate model for this parameter is required. The point source model has been widely used since 1979 and generally provides a good approximation of the received radiant flux. However, it might be less accurate for typical extended lighting sources like LED panels or large area organic LEDs. In this paper, the radiant flux distribution of flat Lambertian rectangular or circular sources is derived from a vector analysis of their irradiance. It is then validated through actual measurements in the case of a circular source. The resulting extended source models thus better capture the light beam pattern of such transmitters to enable a more accurate link budget. It provides at the same time almost identical results to the point source model for small sources and can, therefore, be seen as a natural extension of this already widely used model.
author_names: Juan Camilo Valencia-Estrada

Bastien Bechadergue

Jorge Garcia-Marquez
title: Full Field Radiant Flux Distribution of Multiple Tilted Flat Lambertian Light Sources
venue: IEEE Open Journal of the Communications Society
year: 2020

abstract: In this paper, we propose a multi hop transmission system using visible light communication to transmit audio data. In our proposed transmission system, at the transmitter we encode audio data based on S/PDIF standard a popular standard for digital audio signal, and transmit the encoded audio signal via general LED. At each relay, digital audio signal is improved and amplified before sending. At the receiver, encoded audio signal from photodiode (PD) is decoded, amplified and coverted to analog audio signal. We evaluate our proposed transmission system in a room with flourescent light source. The audio signals obversed at the receiver show that with the support of relays, our proposed transmission system can provide high quality audio transmission from transmiter to receiver via multi hop relays at a long distance.
author_names: Le The Dung

Seungwan Jo

Beongku An
title: VLC Based Multi hop Audio Data Transmission System
venue: GPC
year: 2013

abstract: In this paper, we present and evaluate a practical two way communication system that employs LED as both transmitting and receiving device. Specially, by employing analog switch to isolate transmitting receiving circuits and using microcontroller to control two different data flows going through this analog switch, we build a simple prototype consisting of two transceivers and several relays to demonstrate the possibility of efficiently delivering bi directional text message between two computer users via one hop and multi hop through visible light communication channel. Our proposed system can be further developed to transfer multimedia data which can be considered as an alternative to radio as communication medium.
author_names: Le The Dung

Seungwan Jo

Beongku An
title: Demonstration of Low Complexity LED to LED Two Way Visible Light Communication System
venue: 2016 International Symposium on Computer, Consumer and Control (IS3C)
year: 2016

abstract: Visible light communications (VLC) is a short range optical wireless communication technology that uses light emitting diodes (LEDs) as lighting devices and data transmitters. This paper describes a multiuser VLC system using Hadamard coded modulation (HCM) for indoor data transmission. Considering the peak transmitted power limit of the LEDs, a DC reduced HCM (DCR HCM) is used to reduce the nonlinear clipping distortion. Since the Hadamard codewords have different bandwidth requirements for a given symbol rate, they can be assigned to users with varying hardware capabilities. Optimally assigning codewords to users is found to significantly improve the average throughput, up to twice higher than a random assignment for a typical scenario. When the number of active users is less than the size of the Hadamard matrix used, more than one codeword can be assigned per user, which further improves the throughput. This paper also examines a scenario where multiple lamps in an indoor space transmit the same data. Since the time of arrival for the received signals emitted from different lamps is different, the Hadamard codes received are no longer orthogonal, resulting in multiple access interference and inter chip interference. The number of acceptable codewords is computed based on the specific interference experienced in different parts of the indoor space. The spatial distribution of the maximum throughput is also simulated, showing that the ratio of the maximum to the minimum data rate can be as high as 10 when considering the entire area of a typical indoor room. This article is part of the theme issue 'Optical wireless communication'
author_names: Jie Lian

Mohammad Noshad

Maite Brandt-Pearce
title: Indoor multiuser visible light communication systems using Hadamard coded modulation
venue: Philosophical Transactions of the Royal Society A
year: 2020

abstract: The asynchronous nature of smartphone to smartphone (S2S) based on visible light communication (VLC) imposes a significant challenge on the speed of camera based receiver processing time and algorithm. Recent improvements on the smartphone camera hardware and the current release of the highly customised camera2 application programming interface (Camera2 API) have increased the smartphone's computational capability. This paper presents a comparative study of the acceleration frameworks, which can be used for image processing on Android device to maximize the code performance, thus reducing the computational time of data frame detection. An experimental S2S VLC system is developed for evaluation of the graphical processing unit acceleration (GPU) Android runtime (ART) and native development kit (NDK) based algorithms for processing the captured data. In addition, we determine the total number of processed pixels for multiple frames with the maximum possible detection frequency for S2S VLC. Using the additive property of RGB colour space, two sets of experiments are implemented: firstly the conversion from YUV to RGBA (Red Green Blue Alpha) using all of the available colour based data, which leads to ~500% of improvement in colour conversion time using NDK compared to ART. A gain of 200% is also achieved compared to GPU based algorithms. Secondly, the grayscale filtered YUV to RGBA conversion shows that NDK processing time is 200% faster than the direct ART, which outperforms GPU conversion at lower frame sizes. From the results findings, we propose an optimal approach for camera based VLC application development using Android smartphones.
author_names: Hubert Dzieciol

Hoa Le Minh

Zabih Ghassemlooy

Pham Tien Dat

Tran The Son
title: Comparative Study of Image Processing Performance of Camera Based Visible Light Communication Using Android Acceleration Frameworks
venue: 2018 11th International Symposium on Communication Systems, Networks Digital Signal Processing (CSNDSP)
year: 2018

abstract: This paper proposes a novel design for a PC to PC USB based indoor visible light communications system. The USB interface enables the design to be suitable not only for a PC but also for a variety of mobile devices. The experimental results show that the bandwidth of the established VLC link reaches 8.0 MHz with a measured bit error rate of 10e 5 spanning a distance of 2.0m. The data communication uses the ON OFF keying non return zero (OOK NRZ) format, which is sufficient for transferring a high definition Youtube video stream.
author_names: Tran The Son

Andrew Burton

Hoa Le Minh

Dang Quang Hien
title: Experimental study of PC to PC over a visible light channel using Li Fi USB dongle
venue: 2019 26th International Conference on Telecommunications (ICT)
year: 2019