Optical Bidirectional Beacon based Visible Light Communications

Signals

Visible light communication (VLC ) is an emerging research area in wireless communication. The system works the same way as optical fiber-based communication systems. However, the VLC system uses free space as its transmission medium. The invention of the light-emitting diode (LED) significantly updated the technologies used in modern communication systems. In VLC, the LED acts as a transmitter and sends data in the form of light when the receiver is in the line of sight (LOS) condition. The VLC system sends data by blinking the light at high speed, which is challenging to identify by human eyes. The detector receives the flashlight at high speed and decodes the transmitted data. One significant advantage of the VLC system over other communication systems is that it is easy to implement using an LED and a photodiode or phototransistor. The system is economical, compact, inexpensive, small, low power, prevents radio interference, and eliminates the need for broadcast rights and burie...

IEEE Access

Owing to its several advantages over other wireless schemes, visible light communication (VLC) shall be at the forefront of optical wireless communication technology. However, due to multipath reflections and spatial distribution of light-emitting diode (LED) transmitters, there is an inherent delay spread in the VLC channels. We perform a comprehensive quantitative study on the effect of several practical factors like LED semi-angle, wall reflectivity, number of reflections, number of LED panels, room size, and user locations on the channel delay parameters, namely RMS delay spread and coherence bandwidth of the channel. We present the detailed derivation of the multipath VLC channel model and incorporate the effect of inter-symbol interference in bit error rate (BER) performance of the multipath VLC system. We analyze the average BER of the system under different practical scenarios and determine the penalty in signal to noise ratio entailed by a change in the system parameters mentioned above. We conclude that it is sufficient to model up to three reflections in the VLC channel to emulate the effect of multipath propagation on the channel characterization and BER analysis of the system. The results and analyses presented herein provide critical insights into the effect of multipath reflections in indoor VLC links, particularly the BER performance and channel delay characteristics. We also provide some key recommendations for the design of practical VLC systems by outlining the data rates that can be served under different system configurations. INDEX TERMS Multipath channel, delay spread, coherence bandwidth, inter-symbol interference, bit error rate, visible light communication. I. INTRODUCTION Visible light communication (VLC) is an upcoming optical wireless communication technology that integrates communication and illumination by utilizing the illumination infrastructure of white light-emitting diodes (LEDs) for data communication [1]-[4]. Due to rapid advancements in the field of solid-state lighting devices [5] and a simultaneous boom in Internet traffic over the last few decades, the research on VLC has garnered much interest in the area of wireless communication systems. VLC opens up the untapped visible range (∼400-700 THz) of the electromagnetic spectrum that is unlicensed and free. Thus, VLC promises to support The associate editor coordinating the review of this manuscript and approving it for publication was Wenchi Cheng .

Visible Light Communication (VLC) is an emerging field in Optical Wireless Communication (OWC) which utilizes the superior modulation bandwidth of Light Emitting Diodes (LEDs) to transmit data. In modern day communication systems, the most popular frequency band is Radio Frequency (RF) mainly due to little interference and good coverage. However, the rapidly dwindling RF spectrum along with increasing wireless network traffic has substantiated the need for greater bandwidth and spectral relief. By combining illumination and communication, VLC provides ubiquitous communication while addressing the shortfalls and limitations of RF communication. This paper provides a comprehensive survey on VLC with an emphasis on challenges faced in indoor applications over the period 1979-2014. VLC is compared with infrared (IR) and RF systems and the necessity for using this beneficial technology in communication systems is justified. The advantages of LEDs compared to traditional lighting technologies are discussed and comparison is done between different types of LEDs currently available. Modulation schemes and dimming techniques for indoor VLC are discussed in detail. Methods needed to improve VLC system performance such as filtering, equalization, compensation, and beamforming are also presented. The recent progress made by various research groups in this field is discussed along with the possible applications of this technology. Finally, the limitations of VLC as well as the probable future directions are presented.

2018

In recent years there is growing research in optical wireless communication. This growing popularity isdue to several characteristics like such as large bandwidth that is also not having spectrum r ...

Journal of Lightwave Technology, 2015

Visible light communications (VLC) is a new emerging technology, which provides both data transmission and illumination by utilizing the visible range (370 780 nm) of the electromagnetic spectrum. In order to maximize the available data rate and enhance the users mobility within an indoor environment, it is essential to characterize the communication channel. In this paper we present both analytical and experimental results for a VLC system affected by movement of people for different indoor conditions (i.e. furnished office room, empty hall and corridor). VLC systems utilize multiple light-emitting diodes mounted in the ceiling and the configuration is based on the non-directed line of sight. We consider random movement of people within the room, focusing on the impacts of shadowing and blocking on mobility and link system performance by investigating changes in the channel characteristics using the cumulative distribution function of the received power distribution and the delay profile. We demonstrate the behaviour of communication channels for different scenarios from corridor, the most robust against people movement induced fading, to the office rooms and halls, the most vulnerable to the received power fluctuation.

International journal of wireless and mobile networks, 2023

Provisioning of quality of service (QoS) is a critical issue in visible light communication (VLC) systems and other wireless communication systems. LED lights are becoming widely used for homes and offices for their luminous efficacy improvement. VLC is a new way of wireless communication. Typical transmitters used for visible-light communication are visible-light LEDs, and receivers are photodiodes and image sensors. We present new applications that will be made possible by visible light communication technology. Especially location-based services are considered suitable for visible light communication applications.

The aim of this paper is to determine the viability of Indoor Optical Wireless Communication System. This paper introduces Visible Light Communication along with its merits, demerits and applications. Then the main characteristics of VLC system are described, around which the project is designed. Multiple Input-Multiple Output (MIMO) technique is used in the project in order to enhance the data rate of transmission. Instead of using a system of only one LED and one APD, which transmits only one bit at a time, a system of 4 LEDs and 4 APDs is introduced, which increases the data rates by 300% from the previous case. We observe the signal, noise, SNR, BER etc. across the room dimension. Finally, in the last chapter we summarize our results on the basis of MATLAB simulations and propose some modifications to this model that can be implemented in future.

Practical issues including LED choices, concentrators, and assembling an optical lens and a photodetector have significant impacts on an optical wireless communication link. This paper studied behaviors of the illumination coverage of an indoor VLC. Firstly, effect of diffuse lens is investigated. Array of LEDs with diffuse lens of three different degrees, namely 15, 30, and 60 degree are employed in the experiment at three distinct distances-2, 2.5, and 3 m. Secondly, calculation of the maximum radius of the LED array at the transmitter is discussed in details. Finally, at receiver side, a photodetector is attached with two types of concentrators: biconvex and hemispherical lens. Based on all of our experimental results concerns and recommendation were provided for link design of indoor visible light communications.

Visible light communications (VLC) is a new emerging technology, which provides both data transmission and illumination by utilizing the visible range (370 – 780 nm) of the electromagnetic spectrum. In order to maximize the available data rate and enhance the user’s mobility within an indoor environment, it is essential to characterize the communication channel. In this paper we present both analytical and experimental results for a VLC system affected by movement of people for different indoor conditions (i.e. furnished office room, empty hall and corridor). VLC systems utilize multiple light-emitting diodes mounted in the ceiling and the configuration is based on the non-directed line of sight. We consider random movement of people within the room, focusing on the impacts of shadowing and blocking on mobility and link system performance by investigating changes in the channel characteristics using the cumulative distribution function of the received power distribution and the delay profile. We demonstrate the behaviour of communication channels for different scenarios from corridor, the most robust against people movement induced fading, to the office rooms and halls, the most vulnerable to the received power fluctuation.

2012

This paper presents the development of a Visible Light Communications (VLC) system for a local area network (LAN). The link is analyzed for all development stages and compared with a typical Ethernet system. The VLC system uses a Philips Luxeon Rebel as the transmitter and a Centronic OSD15-5T as the receiver coupled with a blue filter to achieve the required 10 Mb/s bit rates. The distance in which the optical link was measured was up to 1 m, and the link was successful (BER 10-6) for distances up to 0.7 m. To achieve higher distances and therefore to make the system practical in the home or office environment, the number of LEDs used can be scaled.