Design and Experimental Analysis of a Laser-Based Li-Fi Communication System

Radio frequency (RF)-based wireless systems are broadly used in communication systems such as mobile networks, satellite links, and monitoring applications. These systems offer outstanding advantages over wired systems, particularly in terms of ease of installation. However, researchers are looking for safer alternatives as a result of worries about possible health problems connected to high-frequency radiofrequency transmission. Using the visible light spectrum is one promising approach; three cutting-edge technologies are emerging in this regard: Optical Camera Communication (OCC), Light Fidelity (Li-Fi), and Visible Light Communication (VLC). In this paper, we propose a Multiple-Input Multiple-Output (MIMO) modulation technology for Internet of Things (IoT) applications, utilizing an LED array and time-domain on-off keying (OOK). The proposed system is compatible with both rolling shutter and global shutter cameras, including commercially available models such as CCTV, webcams, and smart cameras, commonly deployed in buildings and industrial environments. Despite the compact size of the LED array, we demonstrate that, by optimizing parameters such as exposure time, camera focal length, and channel coding, our system can achieve up to 20 communication links over a 20 m distance with low bit error rate.

Currently, wireless communication systems that use radio frequency are commonly deployed, for example, mobile communication systems, satellite systems, and the Internet of Things (IoT) systems. Based on their easy installation, wireless communication systems have benefits over other wired communication systems. However, using high frequencies to transfer data via wireless communication can hold significant risks for human health. Several researchers have studied this topic using visible light instead of Radio Frequency (RF) waveforms in communication systems. Many potential approaches are relevant in this regard, i.e., visible light communication, light fidelity, free-space optical, and optical camera communication. Artificial intelligence is also influencing the future of industry and people and is used to solve complex problems, create intelligent solutions, and replace human intelligence as the driving force behind emerging technologies such as big data, smart factories, and the IoT. In this paper, we proposed the architecture of the MIMO C-OOK (Multiple-Input Multiple-Output Camera On–Off Keying) scheme, which uses a convolutional neural network for light-emitting diode detection and a deep learning neural network for threshold predictions considering long-distance communication and mobility support. Our suggested method aimed to improve the performance of the traditional camera on–off keying scheme by increasing data rate, communication distance, and low bit error rate. Our suggested technique may achieve a communication distance of up to 22 m with a low error rate when considering the mobility impact (2 m/s, i.e., walking velocity) by controlling the exposure time, focal length, and employing Forward Error Correction code.

The fifth-generation (5G) mobile network is the next paradigm shift in the revolutionary era of the wireless communication technologies that will break the backward compatibility of today’s communication systems. Visible Light Communication (VLC) and Light Fidelity (LiFi) technologies are among the potential candidates that are expected to be utilized in the future 5G networks due to their indoor energy-efficient communications. Realized by Light Emitting Diodes (LEDs), VLC and LiFi possesses a number of prominent features to meet the highly demanding requirements of ultrahigh-speed, massive Multiple-Input Multiple-Output (MIMO) device connectivity, ultra-low-latency, ultra-high reliable and low energy consumption for 5G networks. This paper provides an overview contributions of VLC and LiFi towards 5G networks. Furthermore, we explain how VLC and LiFi can successfully provide effective solutions for the emerging 5G networks.

Modern hospitals are beginning to adopt E-HEALTH as efficient complements to the traditional healthcare services. To support the E-HEALTH services, a locatable, radiation-free and high-capacity communication system is urgently needed in hospitals. Power line communication (PLC) system can use the ubiquitous power line network to power the light-emitting diode (LED) lights while serving as the backbone network for the indoor visible light communication (VLC) systems naturally. In this paper, an integrated broadband power line and visible light communication systems with OFDM modulation is proposed for the indoor hospital applications. This gives a brand-new solution to replace the conventional wireless communication systems in hospitals.

This study evaluates the implementation and performance of a Visible Light Communication (VLC) system designed to transmit text data between two personal computers (PCs). The proposed system utilizes three distinct light-emitting diode (LED) —Single LED, 2 × 2 LED Array, and 4 × 4 LED Array—as transmitters and three types of photodetectors—BPW34 photodiode, solar cell, and light-dependent resistor (LDR)—as receivers. Controlled by an Arduino, the system investigates the relationships between data rate, transmission distance, beam angle, LED configurations, and detector types. Experimental results confirmed that the BPW34 photodiode outperformed the solar cell and LDR in terms of maximum achievable data rate and transmission distance, consistent with its superior bandwidth and sensitivity characteristics. The findings also reveal that, at a zero-degree beam angle, the system employing the BPW34 photodiode achieved a maximum transmission distance of 9.15 m at 1 kilobit per second (kbps) with a single LED configuration, diminishing to 1.24 m at 4 kbps. The 2 × 2 LED array extended the distance 14.20 m at 1 kbps and 2.30 m at 4 kbps. Conversely, the 4 × 4 LED array exhibited the most extensive propagation distances, achieving 16.30 m at 1 kbps and maintaining 3.25 m at 4 kbps. These findings underscore the efficacy of increasing LED array size in enhancing propagation distance, particularly at lower data rates. The study highlights the potential of VLC systems for efficient indoor optical communication, providing valuable insights for optimizing LED configurations and receiver technologies in future applications.

Radio frequency (RF) waveforms are widely used in wireless technologies, such as mobile system, smart factory, and smart home systems. Due to its simplicity of installation, wireless communication is better than wire communication. However, the use of high frequencies for data transmission can be harmful to human health. To replace RF waveform for communication system, Optical Wireless Communication (OWC), which deploys visible light waveform for communication, was researched widely by researchers around the world. Visible Light Communication (VLC), Light Fidelity (LiFi), and Optical Camera Communication (OCC) are the three candidates for replacing RF system. In this research, we present an multiple-input multiple-output (MIMO) modulation system based on on-off keying (OOK) modulation in the time domain and a light-emitting diode (LED) array. By adjusting the exposure time, focal length, forward error correction, and Deep learning for object detection, it is still possible to implement this technique with 10 links in various locations at a distance of 20 m with a velocity of 2 m/s.

De-Noising Scheme for VLC-Based V2V Systems; A Machine Learning Approach

Li-Fi (Light Fidelity) is a new wireless communication technology that is comparable to Wireless Fidelity (Wi-Fi). However, Li-Fi is supposed to be better than Wi-Fi, and this has been theoretically verified. Li-Fi is also thought to make a significant contribution to wireless networks. The practical application of Li-Fi will be discussed in this study. In this paper we chose NOMA because of its ability and efficiency in simultaneously transporting data, as well as its application in 5G cellular networks. VLC stands for visible light communication, as the name implies. In this section, we will investigate how the data transporting capabilities of Li-Fi make use of the visible light emitted by light emitting diodes (LEDs). In this paper, the effectiveness of a non-orthogonal multiple access (NOMA) protocol used in a downlink visible light communication (VLC) system is evaluated for two distinct situations. On a two-user paired NOMA, we create an analytical expression of the system coverage probability for QoS provisioning and show that optimum power allocation coefficients do exist. Additionally, we establish the existence of optimal power allocation coefficients. Last but not least, the numerical and analytical results illustrated in our work show that the VLC single-cell system throughput obtained with our technique is better than that obtained with the earlier strategy. Additionally, it is shown that the suggested alternative lower bound fits the original NOMA-VLC GRPA objective asymptotically using indoor VLC channels.

Today, people prefer supermarkets where they can meet all their needs today for their daily needs. People prefer large markets where they can meet all their needs today for their daily needs. These markets, which have a lot of product capacity, mean more waste of time for the consumer. In such indoor and large areas, it is necessary to plan a route to prevent loss of time. In this study, location determination process was made with visible light communication (VLC) in closed areas and the most suitable route was determined by using Genetic Algorithm (GA) with these locations. It is thought that wireless communication resources will not be sufficient in the future due to the density. VLC systems, developed to solve this problem, are a communication system that uses the light source for data transmission. It has been seen in related studies that this system is quite successful in terms of speed, reliability and energy efficiency. VLC systems basically use a transmitter, receiver and microcontroller for their control. In this study, LED light source, TEMP6000 phototransistor-light sensor and ATMEGA328P (Arduino) are used. Due to its very fast on and off feature, the data sent from the LED light source, is detected by the light sensor TEMP6000. After that, it was modulated using On-Off Keying (OOK). In addition to data transmission, VLC systems, which can be used to determine location especially in indoor areas, can also be used for indoor navigation. Also in this study, indoor positioning is designed on the basis of a market application with VLC. The location data was obtained according to the signal strength, which was transferred from the receiver to Matlab. The operation of the system has been tested on the basis of light sources, products under these sources and the shortest path to the products selected by the user. The shortest distance between the stops selected for this navigation process was found by the Floyd-Warshall algorithm. The shortest path was determined by using a GA for the stops with known distance between them, as in the Traveling Salesman Problem (TSP). In this way, the customer will be able to minimize the time and energy consumed in the market.

This paper presents a real-time 106 Mbit/s visible light communication (VLC) system using only non-return-to-zero on-off keying (OOK-NRZ) modulation and general lighting LED. With a pre-emphasis module based LED driver, the 3-dB modulation bandwidth of VLC link is extended from 4 to 106 MHz. Given the BER upper Limit was 1.3 × 10−3, the highest bit rates achieved through the designed system were 106 and 98 Mbit/s at the distances of 60 and 70 cm, respectively.

Visible Light Communication (VLC) has emerged as a powerful technique for wireless communication systems. Providing high data rate and increasing capacity are the major problems in VLC. Recent evidence suggests that Multiple Input Multiple Output (MIMO) technique can offers improved data rates and increased link range. This paper describes the design and implementation of visible light communication system in indoor environment exploring the benefits of MIMO. The specific objective of this research was to implement a 4×4 Multiple Input (LEDs) Multiple Output (photodetectors)-VLC communication system, where a 16 white power LEDs in four arrays are setting up at transmitter and four RX modules are setting up at receiver side without the need for additional power or bandwidth as well as analyze a mathematical model for a VLC- 4×4 MIMO with different modes such as the suitable angles to cover the entire room. The research designs practically an electronic circuit for the transmitter and receiver with inexpensive components. The power distribution of different propagation modes is calculated for Single Input Single Output (SISO) and MIMO channels in typical room dimensions. The results in this paper indicate that the power is distributed uniformly for entire room when implemented VLC-MIMO as compared to VLC-SISO. Furthermore, a 4×4 MIMO implementing VLC is compared in term of BER vs. SINR with SISO communication system for both Line of Sight (LOS) and Non Line of Sight (NLOS) propagation modes. Comparing the two results of LOS and NLOS, it can be seen that a 4×4 MIMO implementing VLC for LOS perform better than the same system with NLOS due to decreasing in the received power resulted from the multipath effect.

Visible Light Communication (VLC) or Light Fidelity (Li-Fi) with Light Emitting Diodes (LEDs) as transmitter and light sensor as receiver will turn the present lightening system into a communication system. Li-Fi based data communication provides secure communication within the luminous coverage of the light source. Thus, it has several applications in places where Radio Frequency interference is not desirable. Similar to other wireless communication techniques even Li-Fi is used for transmission and reception of digital data. Li-Fi system can also be used to transfer images from one device to another. In this paper, a preliminary study is discussed by proposing and implementing an encoding and decoding scheme for transmission of the binary image using Li-Fi. The proposed system is evaluated based on the light intensity, distance, accuracy, size of the image, image resolution, and transmission time.

Providing network access for multiple users in a visible light communication (VLC) system that utilizes white light emitting diodes (LED) as sources requires new networking techniques adapted to the lighting features. In this paper we introduce two multiple access techniques using expurgated PPM (EPPM) that can be implemented using LEDs and support lighting features such as dimming. Multilevel symbols are used to provide M-ary signaling for multiple users using multilevel EPPM. In the first technique, the M-ary data of each user is first encoded using an optical orthogonal code assigned to the user, and the result is fed into a EPPM encoder to generate a multilevel signal. The second multiple access method uses subsets of the EPPM constellation to apply MEPPM to the data of each user. While the first approach has a larger Hamming distance between the symbols of each user, the latter can provide higher bit-rates for users in VLC systems using bandwidth-limited LEDs. Both techniques are able to support up to 15 simultaneous users transmitting 200 Mb/s with a bit error rate of 10-3 under normal lighting conditions.

The exponential rise in wireless communication demands and allied applications have revitalized academia-industries to develop an efficient and potential solution. Furthermore, the high-pace increasing scarcity of radio spectrum has also alarmed researchers to achieve better Quality of Service (QoS) centric solution. To meet such demands Visible Light Communication (VLC) systems have gained global attention; however, up surging high rate, range and reliability (3R) needs demand better performance. Towards these goals, Multiple Input Multiple Output (MIMO) based VLC systems is an efficient approach; though its efficacy under Multiple Users (MU) conditions remains least explored. Enabling MIMO-MU based VLC can achieve 3R objectives effectively; however, factors like multipath attenuation, interferences and varied impairment-affects makes classical approached confined. The MIMO-MU VLC systems require robust error, noise or interference resilient transmission even under adverse conditions such as non-linear LED, multipath attenuation and interference. Towards these objectives, in this paper a highly robust MIMO-MU VLC system is developed that incorporates an augmented MIMO channel design and combined pre-coding and post equalization schemes. To alleviate major interference probability in MIMO-MU environment, proposed model incorporates time (delay)-multiplexing based data transmission followed by signal adaptive precoding and Volterra Kernel based Hybrid-equalizer. This approach enables interference and noise removal as well as LED non-linearity handling under MIMO-MU VLC communication. The use of a Volterra Kernel based Decision Feedback Equalization with both linear as well as non-linear equalization enables proposed VLC system to exhibit low Bit Error Rate with low modulation index and taps, that optimizes trade-off between performance as well as complexity.

Optical Wireless Communication (OWC) is widely used in current broadband access markets. This is due to the usage of optical radiation through free space for transmission. OWC employs Intensity Modulation with Direct Detection (IMDD) to modulate the intensity of the signal in order to transmit information. This offers a flexible networking solution. OWC systems that operate in the visible band region (390–750 nm) are referred to as Visible Light Communication. VLC has a dual purpose of illumination and communication system. VLC uses On-Off Keying (OOK) and Pulse Position Modulation (PPM). But recently, a noticeable increase in the use of a number of other modulation techniques such as Digital Pulse Interval Modulation (DPIM) and Dual-header Pulse Interval Modulation (DH-PIM) to improve the efficiency in terms of both the bandwidth and power has been observed. This paper concentrates on baseband pulse time modulation techniques that are used to modulate data for OWC and compares OOK, PPM, DH-PIM and DPIM techniques with respect to their spectral efficiency, optical power, bandwidth, transmission capacity, packet transmission rates and peak average power ratio (PAPR).