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This work aims to address the perception that visible light communication (VLC) systems cannot work under the presence of sunlight. A complete framework is presented to evaluate the performance of VLC systems in the presence of solar irradiance at any given location and time. The effect of solar irradiance is investigated in terms of degradations i...
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... where e ∼ N (0, σ 2 ) is the received noise with variance σ 2 . Note that, σ 2 = σ 2 Thermal +σ 2 Shot , σ 2 Thermal = 4K b T F B/R L , and σ 2 Shot = 2qu d F BI b [27]. The parameters K b , T , F , B, R L , q, and I b represent the Boltzmann constant, temperature in Kelvin, detector noise figure, bandwidth, load resistance, electron charge, and background solar radiation current, respectively. ...
In this work, to tackle the line-of-sight (LoS) blockage constraint, a new transmission scheme for vehicle-to-vehicle (V2V) visible light communications (VLC) employing optical reflecting intelligent surfaces (RISs) is proposed and analyzed. To this end, the idea is to address the critical V2V-VLC LoS blockage impact concerning mobility scenarios. Moreover, multiple light-emitting diodes (LEDs)/transmitters-based headlights are employed to enhance the transmission propagation paths. Consequently, it significantly improves the overall reliability of the proposed RIS-aided V2V-VLC model. Further, to emphasize the reliability of the proposed V2V-VLC model, comprehensive path loss and energy efficiency modeling are accentuated. For the realistic V2V-VLC findings, modeling of the path loss corresponding to the intermediate communication links, i.e., between transmitter-RIS and RIS-receiver is emphasized. A novel closed-form expression of a lower bound for the required number of RIS elements to attain a targeted energy efficiency is also developed. Further, to mark interesting research insights, the performance of the proposed RIS-aided V2V-VLC scheme is also compared with the existing scheme. Furthermore, considering the key findings, it is observed that the proposed RIS-aided V2V-VLC scheme offers reliable communication despite mobility-concerned blockage. Moreover, the proposed scheme significantly outperforms the existing scheme concerning the targeted energy efficiency for the reasonable number of required RIS reflection elements.
... Similarly, the free-space optical communication (FSOC) technology is utilized in outdoor and indoor wireless access, communication between spacecraft and satellite constellations, temporary network installation, fiber backup, service acceleration, and last-mile access [1]. Solar noise is considered to be robust in the background light noise category because of its broad spectrum, ranging from 250 to 2500 nm [2], and affects the OWC system's performance for the whole day. The impact of solar noise on the UOWC and FSOC systems has been theoretically discussed in the past. ...
... The photon tracing algorithm was adopted to quantify the amount of solar noise interference in the UOWC system at a certain underwater depth. In [2], a theoretical framework was reported to evaluate the visible light communication (VLC) system performance (system Rx is in a horizontal direction) in the presence of solar irradiance concerning the Sun's position at any given location and time. Giuliano et al. [5] investigated the solar noise impact on the UOWC system (Rx facing vertically upward) utilizing sub-nanometer resolution of the visible spectrum (486.143 and 490.220 nm) as a transmission wavelength. ...
Solar noise, when it interferes with the received signal at the system receiver (Rx) of an optical wireless communication (OWC) system, degrades the system’s performance. The detrimental effect of solar noise on OWC systems has been well established in the literature. This work experimentally demonstrates solar noise interference in the OWC system by pointing the system Rx in various orientations in air and water mediums, e.g., 0° (Rx pointing horizontally leftward), 45°, 90° (Rx pointing vertically downward), 135°, 180° (Rx pointing horizontally rightward), 225°, 270° (Rx pointing vertically upward), and 315°. The experimental outcomes depict the signal’s noise content, spectral leakage, and roll-off rate variation at multiple Rx orientations. We also demonstrate the solar noise interference in transmitting an image through the outdoor underwater OWC link by pointing the system Rx in various orientations. Experimental demonstration confirms that the same OWC system never behaves identically in the presence of solar noise if the system Rx keeps changing its orientation during the maneuver.
... El panel solar ofrece características útiles para generación de energía y también en aplicaciones de comunicaciones ópticas, sin embargo, su baja respuesta en frecuencia ha conducido a trabajos de investigación donde exploran diferentes tecnologías de construcción de paneles solares orgánicos [21], [22], lo cual hace complejo su uso en aplicaciones VLC prácticas. Adicionalmente, se conoce como afecta la irradiación de la luz solar en los sistemas VLC con respecto a los ángulos que forma el sol en el cielo, como lo son la media de Greenwich o la ascensión recta [23]. Sin embargo, pocos estudios indagan sobre los ángulos a los cuales el panel solar puede recibir datos de modulaciones digitales de manera efectiva en sistemas VLC. ...
Visible light communication (VLC) technology allows data to be transmitted using the optical power emitted by light-emitting diodes (LEDs). The optical receiver usually employs light sensors such as photodiodes, image sensors, photoresistors or solar panel. In the last decades, VLC technology has explored the use of solar panels as data receivers, since they offer the service of power generation, in addition to, a larger surface area to capture the light beam. In this paper, we present the performance evaluation of a VLC system based on solar panel and automatic gain control (AGC) with application in access control systems. Three experiments are proposed to evaluate the uses of the solar panel as information receiver in VLC systems: bandwidth (BW) estimation, VLC system performance and panel viewing angle variation. As a result, we were able to determine a BW of 10 kHz and 190 kHz considering the panel without AGC and with AGC. In the context of digital modulation, a RS-232 module of an Arduino UNO development system was used in order to execute the technique of intensity modulation and direct detection IM/DD. The NRZ line code of the serial interface was used to modulate the electric current of the LED with a maximum symbol rate of 38400 baud with a data effectiveness of 91%. Furthermore, we found that AGC improves the dynamic range of the solar panel's viewing angle and the performance of the VLC system.
... Furthermore, in combination with optical filters, the prototype was able to maintain the communication link even when exposed to optical noise levels reaching up to 65,000 µW/cm 2 . On the other hand, the authors of [40][41][42] demonstrated the enhanced noise resilience provided by the use of orthogonal frequency division multiplexing (OFDM) modulation. Again, in combination with optical filtering, it was able to cope with optical noise intensities of up to 50,000 lx [40]. ...
... On the other hand, the authors of [40][41][42] demonstrated the enhanced noise resilience provided by the use of orthogonal frequency division multiplexing (OFDM) modulation. Again, in combination with optical filtering, it was able to cope with optical noise intensities of up to 50,000 lx [40]. ...
Wireless communication represents the basis for the next generation of vehicle safety systems, whereas visible light communication (VLC) is one of the most suitable technologies for this purpose. In this context, this work introduces a novel VLC receiver architecture that integrates a field-of-view (FoV) adaptation mechanism in accordance with the optical noise generated by the sun. In order to demonstrate the benefits of this concept, a VLC prototype was experimentally tested in an infrastructure-to-vehicle (I2V) VLC configuration, which uses an LED traffic light as the transmitter. At the receiver side, an automatic FoV adaptation mechanism was designed based on a mechanical iris placed in front of a photodetector. Adjustments were made based on the values recorded by a multi-angle light sensor, built with an array of IR photodiodes covering an elevation from 0° to 30° and an azimuth from −30° to 30°. Depending on the incidence of solar light, the mechanical iris can adjust the FoV from ±1° to ±22°, taking into account both the light irradiance and the sun’s position relative to the VLC receiver. For experimental testing, two identical VLC receivers were used: one with an automatic FoV adjustment, and the other with a ±22° fixed FoV. The test results performed at a distance of 50 m, in the presence of solar irradiance reaching up to 67,000 µW/cm2, showed that the receiver with a fixed FoV saturated and lost the communication link most of the time, whereas the receiver with an adjustable FoV maintained an active link throughout the entire period, with a bit error rate (BER) of less than 10−7.
... However, efficient compensation methods were not proposed in [18,19]. An optical bandpass blue filter was suggested to mitigate the effects of strong sunlight, albeit at the expense of the reduced data rate and total received signal power [20]. A prism-based method that spatially distributes solar power was proposed in [21] to improve the ratio between signal and solar radiation reached at the receiver. ...
Orthogonal frequency division multiplexing (OFDM) utilizes numerous sub-carriers to achieve high transmission data rates. The frequency selectivity of the channel becomes a crucial factor influencing the communication performance of OFDM-based systems. In optical wireless communication (OWC) systems, the photomultiplier tube (PMT) may experience saturation when the incident optical power approaches its saturation threshold. This paper, for the first time, characterizes the saturation levels of a high-speed PMT based on the measured amplitude in the time domain and the output response of the PMT in the frequency domain. Additionally, an adaptive optical saturation compensation algorithm, leveraging an electronically controlled variable optical attenuator, is proposed to realize a reliable OWC system. Experimental results demonstrate that the proposed saturation compensation method achieves a higher tolerance to large dynamic signal and background radiation compared with that without compensation, while maintaining a satisfactory bit error rate.
... The study outlined in reference Cui et al. (2011) comprises performing a link budget analysis on commercially available LED traffic signal lamps that are off-the-shelf (COTS). The authors endeavoured to disprove the misconception that VLC cannot function in the presence of solar radiation (Islim and Haas 2017;Islim et al. 2018). They evaluated the sun's position and irradiance at a specific geographical location and temporal instance. ...
... The impact of solar irradiation on VLC differs temporally and geographically. Estimating the solar irradiation at a specific moment and position thus requires precisely determining the sun's celestial position (Islim et al. 2018). The currently available literature contains many algorithms that aim to calculate the solar position and irradiance with varying degrees of complexity and precision. ...
Visible light communication (VLC) can serve as a supplement to the radio frequency to address its inherent constraints. VLC can be easily implemented in vehicles using their existing LED components. Sunlight interference can cause significant variation in the background noise powers, leading to signal-to-noise ratio (SNR) degradation in vehicular VLC (VVLC) communication. Hence, it is necessary to improve the performance besides interference. Allan variance is a temporal analysis approach that can extract the noise from the received data. In this article, an Allan variance-based adaptive noise canceller for a VVLC system is proposed and evaluated. Based on the Allan variance obtained, the step size and the number of taps of the adaptive filter are adjusted for superior performance. This proposed filter effectively mitigates the pronounced autocorrelation induced by the noise interference. It yields about an 85% bit error rate (BER) reduction compared to the conventional filter. This improved convergence underscores the potential for enhanced communication performance and reliability. The balanced distribution of the Manchester encoded signal outperforms NRZ encoding. Thus, this work contributes a novel adaptive noise canceller design for a VVLC system and also provides valuable insights to the significance of Allan variance in the VLC system performance.
... [5][6][7][8] Both visible and infrared optical wireless communications can experience significant solar interference, whereas the strong filtering effect of the atmosphere results in low background-noise of DUV radiation on the ground. [9][10][11][12] Studies of DUV communication date back to the 1970s. 13,14 With recent advancements in DUV light-emitting diodes (LEDs) and high-sensitivity photodetectors, emerging DUV communication technology is attracting more interest in the field of wireless communication and supports a feasible method for anti-electromagnetic-interference communication. ...
Emerging deep-ultraviolet (DUV) light communication with attractive features fulfills the increasing demand for novel wireless communication without electromagnetic interference or solar noise influence. Here, we propose, manufacture, and characterize a solar-blind full-duplex light communication system using 275-nm DUV light-emitting diodes (LEDs). Four DUV LEDs connected in series form a unit, and the transmitter consists of an array of three independent units, which can be synchronously controlled using a main processing unit to modulate the emitted light. A solar-blind filter is inserted in front of the receiver due to the lack of an ultraviolet photodetector. Both the transmitter and receiver are encapsulated together to manufacture a full-duplex DUV light communication system, which can independently transmit and receive data with a maximal communication distance of 7 m at the same time. All users within a 46 m2 area of the system have access to the DUV communication network through an integrated wireless module. Real-time video is demonstrated and different types of files could be shared. Based on Transmission Control Protocol/Internet Protocol (TCP/IP), the system is finally performed in sunlight with a transmission rate of 10 Mbps and a packet loss rate of 1.28%.
... The background noise can be reduced by implementing a diversity receiver with a selective combining technique, which results in a 5 dB signal to noise ratio (SNR) improvement, as shown in [6]. Furthermore, a 6.47 dB improvement in the SNR can also occur by implementing optical filtering at the receiver (Rx) side, as illustrated in [7]. ...
DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) has been introduced to visible light networking framework for connected vehicles (LiNEV) systems as a modulation and multiplexing scheme. This is to overcome the light-emitting diode (LED) bandwidth limitation, as well as to reduce the inter-symbol interference caused by the multipath road fading. Due to the implementation of the inverse fast Fourier transform, DC-OFDM suffers from its large peak-to-average power ratio (PAPR), which degrades the performance in LiNEV systems, as the LEDs used in the vehicles’ headlights have a limited optical power-current linear range. To tackle this issue, discrete Fourier transform spread-optical pulse amplitude modulation (DFTS-OPAM) has been proposed as an alternative modulation scheme for LiNEV systems instead of DCO-OFDM. In this paper, we investigate the system performance of both schemes considering the light-emitting diode linear dynamic range and LED 3 dB modulation bandwidth limitations. The simulation results indicate that DCO-OFDM has a 9 dB higher PAPR value compared with DFTS-OPAM. Additionally, it is demonstrated that DCO-OFDM requires an LED with a linear range that is twice the one required by DFTS-OPAM for the same high quadrature amplitude modulation (QAM) order. Furthermore, the findings illustrate that when the signal bandwidth of both schemes significantly exceeds the LED modulation bandwidth, DCO-OFDM outperforms DFTS-OPAM, as it requires a lower signal-to-noise ratio at a high QAM order.
... Previous works [8], [9], [10] assumed a 52 Lambertian model for vehicle headlights, which does not 53 accurately capture their illumination characteristics [11]. Also, 54 ideal weather conditions were assumed, while in reality, 55 atmospheric attenuation [12] and background noise [13] can 56 significantly degrade performance. Additionally, none of these 57 studies provided closed-form expressions for the number of 58 RIS elements required to achieve targeted energy efficiency 59 or spectral efficiency, which offer valuable insights for sys-60 tem design and performance evaluations. ...
The common underlying assumption in vehicle-to-vehicle (V2V) visible light communication (VLC) is that connected vehicles travel serially, so a line-of-sight (LoS) link is always maintained. However, in scenarios where in-parallel vehicles communicate to avoid crashes, LoS link is usually absent. In this letter, we utilize optical reflecting intelligent surfaces (RISs) to relax the LoS constraint. Based on realistic V2V-VLC channel modeling, we derive novel closed-form expression for the number of RIS elements required to achieve a target energy/spectral efficiency in RIS-aided V2V-VLC system. We further investigate the impact of transceiver, system, and environment parameters on the system performance.
... Nevertheless, due to many unique advantages, the research community has continued to work on this issue, and, thus, current VLC systems have managed to make significant progress in this direction. It should be emphasized that although noise resilience is crucial for vehicular VLC systems [9,10], this issue is vital for indoor VLC systems as well [27]. On the other hand, the progress toward optical-noise-resilient VLC systems has been mostly driven by vehicular VLC systems developers. ...
... The authors of [27] addressed the problems associated with strong sunlight exposure based on the use of a narrow band-pass optical filter and orthogonal frequency-division multiplexing (OFDM) modulation. Thus, these techniques enabled them to provide a 1 Gb/s data rate under a 50,350 lux noise exposure, for a 14 cm range. ...
Visible light communications (VLC) are an emerging technology that is increasingly demonstrating its ability to provide wireless communications in areas where radio frequency (RF) technology might have some limitations. Therefore, VLC systems offer possible answers to various applications in outdoor conditions, such as in the road traffic safety domain, or even inside large buildings, such as in indoor positioning applications for blind people. Nevertheless, several challenges must still be addressed in order to obtain a fully reliable solution. One of the most important challenges is focused on further improving the immunity to optical noise. Different from most works, where on–off keying (OOK) modulation and Manchester coding have been the preferred choices, this article proposes a prototype based on a binary frequency-shift keying (BFSK) modulation and non-return-to-zero (NRZ) coding, for which the resilience to noise is compared to that of a standard OOK VLC system. The experimental results showed an optical noise resilience improvement of 25% in direct exposure to incandescent light sources. The VLC system using BFSK modulation was able to maintain a maximum noise irradiance of 3500 µW/cm2 as compared with 2800 µW/cm2 for the OOK modulation, and an improvement of almost 20% in indirect exposure to the incandescent light sources. The VLC system with BFSK modulation was able to maintain the active link in an equivalent maximum noise irradiance of 65,000 µW/cm2, as opposed to the equivalent 54,000 µW/cm2 for the OOK modulation. Based on these results, one can see that based on a proper system design, VLC systems are able to provide impressive resilience to optical noise.
