Search

This paper focuses on image sensor communication (ISC) using cameras to receive wireless signals transmitted by visible lights. We summarize the technical principles of ISC from the perspective of transmitting devices. An introduction to the development and applications of ISC was provided, starting with the history of image sensors and visible light communication (VLC). Moreover, the communication mechanism of ISC using complementary metal–oxide–semiconductor (CMOS) sensors is explained in this paper. Specifically, we investigate studies using an optical communication image sensor and the rolling shutter technique for high-speed ISC. Further, we highlight three distinctive transmitting devices in ISC: a LED array, rotating LEDs, and displays, and explain them in terms of structure and signal transmission methods. In particular, we present the parallel transmission of LED arrays and their application in traffic systems and introduce an optical flow-based signal transmission method using rotating LEDs. In addition, two visual transmission techniques in displays-based-ISC using brightness-difference and high-frequency flashing are introduced, respectively. This paper intuitively explains these ISC techniques and reveals ISC’s high versatility.

This study presents insights into high-speed optical wireless communication (OWC) within plastic pipes, introducing a Gbps-capable alternative for challenging environments. Utilizing a 1W LED with five wavelengths, the experiment explores signal power, attenuation, and bandwidth characteristics. Notably, the blue LED achieves an unprecedented 58.64 MHz bandwidth, red and purple LEDs demonstrate novel bandwidths of approximately 25.23 MHz, and green and yellow LEDs exhibit unique bandwidths of 23.75 MHz and 9.62 MHz, respectively. The attenuation parameters for different wavelengths provide numerous insights, showcasing the novelty of this research and its potential applications in robot communication within plastic pipes. Concurrently, the paper introduces an approach to address the temperature impact on five distinct wavelength LEDs in OWC. By focusing on variations in LED bandwidth and optical power, an optimal heat sink design is proposed. This design achieves a remarkable minimum temperature of 27.06 degrees C and reduces the chip LED device's response time from 15 to 9 seconds. The significance lies in the novelty of the proposed heat sink, which incorporates variables such as fin thickness, height, air gap width, number of fins, and airflow rate, marking a substantial advancement in thermal management for OWC systems., QC 20240702

The combined use of distributed multiple-input multiple-output (D-MIMO) and orthogonal frequency division multiplexing (OFDM) with adaptive bit and power loading is seen as a powerful tool to overcome limitations of the optical wireless communication (OWC) channel and of light-emitting diodes (LED)s. Although extensive research into efficient MIMO algorithms has been performed for communications via radio, these may not be indiscriminately re-used in LED-based OWC systems. The main reasons are that the OWC channel has different properties, the LEDs have power-constraints, and eye-safety regulations apply. For adoption in a practical system, the computational complexity of the algorithms must also be taken into account. Fortunately, physical properties of the LED D-MIMO channel allow us to reduce signalling overhead, estimation effort and complexity. This paper presents, compares, and discusses both the performance and the computational cost of several new power-loading strategies to enhance the throughput of LED-based OFDM D-MIMO OWC systems respecting the individual power constraints of the light sources. To cope with the low-pass nature of LEDs, we optimize how much power to load on each MIMO spatial stream, on each sub-carrier and what bandwidths to use. The CVX toolbox for convex optimization gives us an optimum but it is orders of magnitude more complex than highly effective heuristic approaches. A simple approach stays $1$ dB short of the optimum: it equally splits power among MIMO streams within the LED power constraints, and it uniformly spreads the power over a bandwidth that is optimized per stream. A similar strategy, but selecting optimized powers per stream brings us as near as 0.1 dB to the optimum. To evaluate the complexity of bit and power allocations, we investigate, optimize, and accelerate the speed of iterative schemes. The proposed approaches give new choices for chipset manufacturers and LED-based OFDM D-MIMO OWC system designers to improve pe

This article presents two dual-photodiode (PD) dif-ferential optical receivers that achieve double photodetection area to support gigabit-per-second optical wireless communication (OWC), while maintaining the receiver bandwidth. To enable differential light detection with a single incident light beam, a dual-PD OWC receiver architecture is proposed. In this architecture, two PDs are connected to the receiver complemen-tarily without sacrificing the receiver bandwidth, and meanwhile, remain properly reversely biased. In addition, an adaptive dc photocurrent cancellation (ADPC) circuit is employed to prevent the saturation of the receivers under strong and imbalanced incident light. Based on the proposed architecture, two OWC receivers are implemented, including a proposed receiver and a reference one. In the proposed receiver, a low-noise shunt-feedback transimpedance amplifier (SF-TIA) with differential-pair-based current reuse and cross-coupled resistive feedback is proposed to enhance the sensitivity. In contrast, the reference receiver employs positive capacitive feedback to improve the transimpedance amplifier (TIA) performance. Both receivers have been fabricated with a standard 180 nm CMOS process and have been wire-bonded to two PDs. Experimental results indicate that both receivers can detect optical signals with data rates up to 2 Gb/s, and the proposed receiver architecture has significantly improved the bit error rate (BER) at 1.5 Gb/s from worse than 10(-6)-10(-9) (error-free) with constrained optical power density. Moreover, the proposed receiver achieves an input sensitivity of 3.4 mu A(pp) due to the superior performance of the proposed TIA, which outperforms the sensitivity of 10.4 mu A(pp) from the reference receiver. Both sensitivities are measured at 1.5 Gb/s for a BER of 10(-9) (error-free). The power consumption of the proposed and the reference receiver are 24.3 and 19.1 mW, respectively, excluding the output driver.

Optical Wireless Communication (OWC) has attracted significant attention from academia and industry as a promising solution to complement traditional radio frequency communication. In Light-Fidelity (LiFi) networks, to enable soft handover and provide robustness against blockage of the line-of-sight links, LiFi receivers are designed to see multiple LiFi transmitters within their field-of-view. To trade-off spatial multiplexing with harmful interference, a proper user scheduling technique is required. In this work, we first derive practical and exact expressions for determining which simultaneous transmissions will create harmful interference and should be scheduled in multiple time-slots. Afterwards, relying on this expression, we propose our semi-distributed Spatially Extended TDMA algorithm, which is based on a time division contention-free access scheme. In contrast to more complex algorithms in the state-of-the-art, our scheduling protocol can reduce the computation time while also achieving a superior minimal user throughput. For a scenario with 9 transmitters and up to 15 receivers, our protocol is at least a factor 120 faster and can improve the minimal user throughput up to 91%, making it suitable for practical roll-out as a promising solution for very dense LiFi networks.

Optical Wireless Communication (OWC) has attracted significant attention from academia and industry as a promising solution to complement traditional radio frequency communication. In Light-Fidelity (LiFi) networks, to enable soft handover and provide robustness against blockage of the line-of-sight links, LiFi receivers are designed to see multiple LiFi transmitters within their field-of-view. To trade-off spatial multiplexing with harmful interference, a proper user scheduling technique is required. In this work, we first derive practical and exact expressions for determining which simultaneous transmissions will create harmful interference and should be scheduled in multiple time-slots. Afterwards, relying on this expression, we propose our semi-distributed Spatially Extended TDMA algorithm, which is based on a time division contention-free access scheme. In contrast to more complex algorithms in the state-of-the-art, our scheduling protocol can reduce the computation time while also achieving a superior minimal user throughput. For a scenario with 9 transmitters and up to 15 receivers, our protocol is at least a factor 120 faster and can improve the minimal user throughput up to 91%, making it suitable for practical roll-out as a promising solution for very dense LiFi networks.

Vehicle to Vehicle (V2V) Communication is a developing technology that aims to make road transportation systems intelligent, to avoid accidents and traffic congestions. This thesis presents Optical Wireless Communication (OWC) as a solution that will drive the next generation of V2V systems. The current standards for V2V and vehicle to infrastructure (V2I) communication, based on radio frequency techniques, are revised. Also, the current standard for Visible Light Communication (VLC), IEEE 802.15.7 is analyzed. This project also shows the first steps towards a cost-effective implementation of V2V VLC taking advantage of already available hardware in vehicles. Finally, a transmission system is presented aiming to demonstrate an adaptation of current VLC standards for V2V and V2I communication. Another system based on IR communication is also presented. These are presented as an alternative for V2V and V2I solutions based on radio frequency techniques, opening the door to a relevant industrial application of optical wireless communication.

Indoor optical wireless communication (OWC) using steerable infrared beams is regarded as an important component in future 5G network. Photonic integration technologies can meet the criteria of such application, and provide low-cost, high-performance and very compact chips. In this paper, we review the recent development of photonic integration technologies suitable for indoor OWC application, and discuss in detail the current status and future opportunities of several key devices, such as the chip to free space couplers, integrated receivers and transmitters.

In this paper, a novel integrated optical wireless receiver/transmitter is presented. The device is realized on an InP membrane platform where active and passive components are integrated monolithically. It can be reconfigured to either receiver mode or transmitter mode, by simple control on the operation mode of a photodetector (short SOA). Demonstration of the receiver mode in an indoor optical wireless system has shown 17.4-Gbps OFDM signal transmission, illustrating the potential of this concept.

Indoor optical wireless communication (OWC) using steerable infrared beams is regarded as an important component in future 5G network. Photonic integration technologies can meet the criteria of such application, and provide low-cost, high-performance and very compact chips. In this paper, we review the recent development of photonic integration technologies suitable for indoor OWC application, and discuss in detail the current status and future opportunities of several key devices, such as the chip to free space couplers, integrated receivers and transmitters.

In this paper, a novel integrated optical wireless receiver/transmitter is presented. The device is realized on an InP membrane platform where active and passive components are integrated monolithically. It can be reconfigured to either receiver mode or transmitter mode, by simple control on the operation mode of a photodetector (short SOA). Demonstration of the receiver mode in an indoor optical wireless system has shown 17.4-Gbps OFDM signal transmission, illustrating the potential of this concept.