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We present a micro-LED-on-CMOS digital light projector array operating up to 0.5 Mfps. The 128x128 pixel array has individual control of each pixel and can operate with 32 grayscale levels and emit nanosecond pulses.

In this paper, we propose and validate an artificial neural network-based equalizer for the constant power 4-level pulse amplitude modulation in an optical camera communications system. We introduce new terminology to measure the quality of the communications link in terms of the number of row pixels per symbol Npps, which allows a fair comparison considering the progress made in the development of the current image sensors in terms of the frame rates and the resolutions of each frame. Using the proposed equalizer, we experimentally demonstrate a non-flickering system using a single light-emitting diode (LED) with Npps of 20 and 30 pixels/symbol for the unequalized and equalized systems, respectively. Potential transmission rates of up to 18.6 and 24.4 kbps are achieved with and without the equalization, respectively. The quality of the received signal is assessed using the eye-diagram opening and its linearity and the bit error rate performance. An acceptable bit error rate (below the forward error correction limit) and an improvement of ~66% in the eye linearity are achieved using a single LED and a typical commercial camera with equalization.

Digital light projector systems are crucial components in applications, including computational imaging, fluorescence microscopy, and highly parallel data communications. Current technology based on digital micromirror displays are limited to absolute frame rates in the few tens of kiloframes per second and require the use of external light sources and coupling optics. Furthermore, to realize gray-scale pixel values using duty cycle control, frame rates are reduced proportionally to the number of gray levels required. Here we present a self-emissive chip-scale projector system based on micro-LED pixels directly bonded to a smart pixel CMOS drive chip. The 128 × 128 pixel array can project binary patterns at up to 0.5 Mfps and toggle between two stored frames at megahertz rates. The projector has a 5-bit gray-scale resolution that can be updated at up to 83 kfps, and can be held in memory as a constant bias for the binary pattern projection. Additionally, the projector can be operated in a pulsed mode, with individual pixels emitting pulses down to a few nanoseconds in duration. Again, this mode can be used in conjunction with the high-speed spatial pattern projection. As a demonstration of the data throughput achievable with this system, we present an optical camera communications application, exhibiting data rates of > 5 Gb / s .

We demonstrate the integration of Cube-Sat on-board equipment with a field programmable array gate-based light-emitting diode/single-photon avalanche photodiode transceiver using an inter-integrated circuit protocol.

In general, visible light communication (VLC) systems, which utilise white light-emitting diodes (LEDs), only offer a bandwidth limited to the lower MHz region. Therefore, providing VLC-based high data rate communications systems using VLC becomes a challenging task. To address this challenge, we propose a solution based on multiplexing in both the frequency and space domains. We experimentally demonstrate a 4 ${\boldsymbol{\times }}$ 4 imaging multiple-input multiple-output (MIMO) VLC system (i.e., space multiplexing) utilising multiband carrierless amplitude and phase ( m -CAP) modulation (i.e., frequency multiplexing). Independently, both MIMO and m -CAP have separately shown the remarkable ability to improve the transmission speeds in VLC systems, and hence, here we combine them to further improve the net data rate. We investigate the link performance by varying the number of subcarriers m , link distance $\boldsymbol{L}$ , and signal bandwidth $\boldsymbol{B_{\text{sig}}}$ . From all the values tested, we show that a data rate of $\sim$ 249 Mb/s can be maximally achieved for m = 20, $B_{\text{sig}}$ = 20 MHz, and $\boldsymbol{L}$ = 1 m, at a bit error rate of ${3.2\times 10^{-3}}$ using LEDs with $\sim$ 4 MHz bandwidth.

This paper focuses on the performance analysis of a camera based vehicle-to-vehicle visible light communication system employing undersampled phase shift on-off keying modulation under interference scenario. Two Nissan Qashqai front lights with daylight running light emitting diodes based lamps are used for communications. The bit error rate (BER) performance of the proposed system is experimentally measured for a transmission span up to 24m focusing mostly on the side interference due to reflections. Based on experimental data we demonstrate reduction of the system performance due to the side reflection and illumination of the detector by other light sources which has to taken into account during further data processing. We provide with further statistics for particular shuter speed and transmitter power setting and discus BER improvement especially to meet FEC via the method of adaptive region of interest.

In this Letter, we develop a novel technique, to the best of our knowledge, to increase the link span ( L s ) of a rolling shutter (RS)-based optical camera communications (OCC) system by reducing the spatial bandwidth of the camera in the out-of-focus regions. We demonstrate a 400 m line-of-sight RS-based OCC link, which is to date the longest L s reported in these systems, and develop a detection method to extract the information out of the video frames, successfully. The proposed system relaxes the condition of a large surface area for the transmitter light source. Consequently, we show that at 400 m L s and exposure times of 100–80 µs, a data rate of 450 bps is achieved successfully.

In the VLC context, pulse position modulation (PPM) and similar modulations are typically used when the overall complexity of the transmitter is required to be low or the system needs to support dimming, i.e., dynamically control the illumination level of the transmitter. However, despite the power efficiency of PPM, it is known to be bandwidth inefficient. Having known the trade-off between reliability and spectral efficiency, in this paper we propose a PPM-based space-time block coding (STBC) technique named as quasi-trace-orthogonal (QTO), derived from trace-orthogonal, to increase the spectral efficiency of PPM VLC’s by limiting the reliability loss. We provide Monte-Carlo simulations for a $4\times 4$ MIMO-VLC system and validate the results experimentally, and show that for a given signal-to-noise-ratio, the QTO-STBC based 4-PPM VLC system offers higher spectral efficiency at a cost of higher symbol error rate compared to trace-orthogonal STBC.

The ever-increasing number of vehicles on a global level signifies the need for communications between vehicles and the surrounding environment. Visible light communications (VLC) is a viable complementary technology to congested radio-frequency-based wireless systems. In order to increase the reliability of the VLC link, two novel algorithms based on (i) channel inversion (CI) and (ii) frame subtraction and CI (FSCI) schemes are proposed to successfully extract the data in a non-line-of-sight multiple-input–multiple-output spatial-division multiplexing optical camera communications system. We have adopted differential modulation and frame subtraction schemes and proposed a unique packet structure to mark the packet and the position of the footprint of transmitters (Txs) in the image frame. We show that the FSCI scheme with much simpler receiver structures can offer almost the same bit error rate performance compared with the hybrid selection/equal gain combining (HS/EGC) technique at lower transmit power (illumination) levels of 20dBm for multiple Txs. Compared with HS/EGC, CI schemes have a higher tolerance to the spacing between Txs, where the payload threshold level can be set to a fixed value of 0.5.

International audience; A simplified model of the camera for optical camera communications (OCC) based on the rolling shutter effect is proposed and experimentally verified. In OCC, the key parameters are the exposure time, which is proportional to the DC gain and inversely proportional to the bandwidth, and the rolling shutter delay or the sampling period. We demonstrate a good agreement between experimental and numerically simulated results for the proposed receiver model.

International audience; The increasing use of light emitting diodes in traffic lights offer excellent opportunities for implementation of visible light communications (VLC) based wireless technology as part of intelligent transport systems in smart environments. In this paper, we experimentally demonstrate vehicle to infrastructure (V2I) communications based on the VLC technology using a real traffic light and a camera over a link span of up to 80 m. We show a reduction in the modulation depth of the signal from 100% to 50% in order to track the light source when sending '0' symbols. Also presented is the effect of operating the camera in the focused and defocused modes. The results show transmission success rates of 100% and 90% over link spans of 70 m and 80 m, respectively under specific test conditions.

Optical wireless communications (OWC) are emerging as cost-effective and practical solutions to the congested radio frequency-based wireless technologies. As part of OWC, optical camera communications (OCC) have become very attractive, considering recent developments in cameras and the use of fitted cameras in smart devices. OCC together with visible light communications (VLC) is considered within the framework of the IEEE 802.15.7m standardization. OCCs based on both organic and inorganic light sources as well as cameras are being considered for low-rate transmissions and localization in indoor as well as outdoor short-range applications and within the framework of the IEEE 802.15.7m standardization together with VLC. This paper introduces the underlying principles of OCC and gives a comprehensive overview of this emerging technology with recent standardization activities in OCC. It also outlines the key technical issues such as mobility, coverage, interference, performance enhancement, etc. Future research directions and open issues are also presented.

In this paper, a non-line-of-sight multiple-input multiple-output space and time division multiple access optical camera communications system is proposed for an indoor environment. Mask matching and equal-gain combining (EGC) schemes as well as differential modulation and frame subtraction are used. We propose a unique packet structure to label the transmitters and a new detection method for data extraction from the captured video streams. We outline a comprehensive theoretical model and have developed an experimental testbed to evaluate the performance of the proposed system. The results highlight that zooming and defocusing of the camera does not have a significant impact on the system performance, therefore the aperture can be set to its maximum value. The system performs well over a link span of 10 m with a low transmit power of 12 mW and in the presence of ambient light due to the non-linear conversion of RAW to JPEG. Using mask matching and EGC improves the tolerance of the system to the noise.

We propose, for the first time to the best of our knowledge, a novel non-line-of-sight 2×N indoor optical camera communication system, where N is the number of pixels in the camera with a unique packet structure and a detection methodology for extracting the data from the recorded video streams. A comprehensive theoretical model for the proposed system is presented. The proposed system is experimentally investigated, and the measured results show that higher International Standards Organization (ISO) levels and exposure times lead to a reduced transmit power level by 3 dB for every doubling of the exposure time and ISO at a bit error rate of 10−3. It is also shown that when the overlapping area of two interfering transmitters is larger than approximately 30% of the footprints, the data cannot be recovered.