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In the domain of the Internet of Things (IoT), Optical Camera Communication (OCC) has garnered significant attention. This wireless technology employs solid-state lamps as transmitters and image sensors as receivers, offering a promising avenue for reducing energy costs and simplifying electronics. Moreover, image sensors are prevalent in various applications today, enabling dual functionality: recording and communication. However, a challenge arises when optical transmitters are not in close proximity to the camera, leading to sub-pixel projections on the image sensor and introducing strong channel dependence. Previous approaches, such as modifying camera optics or adjusting image sensor parameters, not only limited the camera’s utility for purposes beyond communication but also made it challenging to accommodate multiple transmitters. In this paper, a novel sub-pixel optical transmitter discovery algorithm that overcomes these limitations is presented. This algorithm enables the use of OCC in scenarios with static transmitters and receivers without the need for camera modifications. This allows increasing the number of transmitters in a given scenario and alleviates the proximity and size limitations of the transmitters. Implemented in Python with multiprocessing programming schemes for efficiency, the algorithm achieved a 100% detection rate in nighttime scenarios, while there was a 89% detection rate indoors and a 72% rate outdoors during daylight. Detection rates were strongly influenced by varying transmitter types and lighting conditions. False positives remained minimal, and processing times were consistently under 1 s. With these results, the algorithm is considered suitable for export as a web service or as an intermediary component for data conversion into other network technologies.

Se presenta un análisis de las motivaciones que configuraron procesos de movilidad social educativa en un grupo de ochenta jóvenes egresados de la Universidad de Antioquia, para lo cual se aplicó una encuesta sobre el acceso, transcurso y egreso de la universidad. La conclusión principal es que la edad no es impedimento para construir el proyecto de vida y generar acciones que lleven a los jóvenes conscientemente a cumplir sus deseos a través de la educación universitaria, que les brinda satisfacción en el ser principalmente, evidenciando sus impactos positivos a pesar de las dificultades para acceder a ella.

Abstract Optical camera communication is foreseen to have an essential role in future systems requiring wireless communication capability. In this regard, high‐spectral‐resolution cameras, such as multispectral (MS) cameras, present specific characteristics that can be exploited to provide new features to optical camera communication links. Using the MS cameras' features to take advantage of the light‐emitting diode (LED) behaviour in a novel communication scheme is focussed. Notably, LED spectral response curves are different when their temperature changes. Therefore, these differences can be detected based on the MS cameras' spectral resolution. Thus, more than one communication channel can be attained using the same LED device since the camera can distinguish the different LED spectral signatures. This new approach is analysed in this work, including some equalisation techniques applied to the channel matrix in the receiver to improve the extraction of the transmitted signal reducing the inter‐channel interference. For the specific MS camera employed in the experiments, up to two distinct channels could be obtained with the same transmitter at different temperatures, getting a bit error rate below the forward error correction limit. However, obtaining satisfactory results is highly dependent on the variation that temperature causes in the spectral signatures of the LEDs, so further experiments are recommended in future work with different devices.

Visible Light Communication (VLC) is emerging as a promising technology to meet the demands of fifth-generation (5G) networks and the Internet of Things (IoT). This study introduces a novel RGB-LED-based VLC system design that leverages autoencoders, addressing the often overlooked impact of optical-to-electrical (O/E) conversion efficiency. Unlike traditional methods, our autoencoder-based system not only improves communication performance but also mitigates the negative effects of O/E conversion. Through comprehensive simulations, we show that the proposed autoencoder structure enhances system robustness, achieving superior performance compared to traditional VLC systems. By quantitatively assessing the impact of O/E conversion—a critical aspect previously overlooked in the literature—our work bridges a crucial gap in VLC research. This contribution not only advances the understanding of VLC systems but also provides a strong foundation for future enhancements in 5G and IoT connectivity.

This paper presents an experimental evaluation of a wearable light-emitting diode (LED) transmitter in an optical camera communications (OCC) system. The evaluation is conducted under conditions of controlled user movement during indoor physical exercise, encompassing both mild and intense exercise scenarios. We introduce an image processing algorithm designed to identify a template signal transmitted by the LED and detected within the image. To enhance this process, we utilize the dynamics of controlled exercise-induced motion to limit the tracking process to a smaller region within the image. We demonstrate the feasibility of detecting the transmitting source within the frames, and thus limit the tracking process to a smaller region within the image, achieving an reduction of 87.3% for mild exercise and 79.0% for intense exercise.

Alley-cropping agroforestry enhances carbon sequestration compared to open cropland and open grassland, and improves soil biological habitat and erosion resistance relative to open cropland, based on measured ecosystem functions at five sites in Germany.

The energy consumption of the Internet of underwater things (IoUT) nodes is a capital aspect that dramatically affects the applicability of wireless optical technologies in several scenarios, such as ocean monitoring or underwater sensor networks. Simultaneous lightwave information and power transfer (SLIPT) is a cost-effective and energy-efficient solution for energy-constrained wireless systems. Nonetheless, the reported battery-charging times for underwater operations are high, which should be improved to make this technology attractive enough to be considered for actual implementations. This paper provides a new SLIPT strategy, introducing a specific optical signal transmission scheme by controlling the transmitted direct current (DC) level component. The scheme is based on a DC-On Off Keying (OOK) modulation with an adjustable signal range (SR) to improve the energy-harvesting process and battery-charging time for underwater operations. The results reveal that the system provides a signal-to-noise ratio higher than 28 dB and the bit-error rate of less than 10−10 which is below the forward error correction limit with improved charging time around 30 minutes and 15 seconds for 5 F and 9.4 mF, respectively over 20 cm, and 63 seconds for 9.4 mF in 50 cm link distance.

Puccinia triticina, as the causal agent of leaf rust, is one of the most important fungal diseases of wheat. Effective resistance can prevent yield losses and reduced quality. More than 80 leaf rust resistance (Lr genes) genes are known, most of which are vertical resistance genes vulnerable to breakdown by virulent races of leaf rust. Therefore, breeding activities are focused on quantitative resistance genes, e.g., Lr34 and Lr46. In an F2 population derived from the partially resistant cultivar Pavon F76, carrying Lr46 at the adult plant stage, and the susceptible spring wheat variety Thatcher, seedling resistance QTLs could be detected, independent of the expected chromosomal regions for already known Lr genes. Using innovative phenotyping methods, e.g., microscopic evaluation and counting of uredospore pustules, three QTLs were detected on chromosomes 2B, 4D and 7D. These resistance QTLs explained more than 11% of the phenotypic variance. KASP markers can be derived from markers within the QTL peaks and are available for marker-assisted selection. The study proves again that Mendelian rules do not only describe the inheritance of phenotype. They also apply to the inheritance of the marker alleles and are therefore essential for marker selection and marker-assisted breeding.

In this paper, we explore the potential applications of Optical Wireless Communications in the tourism industry, considering both indoor and outdoor scenarios and different transmission speeds. They range from high-speed atmospheric outdoor links (Free-Space Optics (FSO)) to indoor systems based on high-speed lighting networks (known under the trade name LiFi©) or low-speed services support the Internet of Things networks, using visible light (VLC) or IR emitters, with receivers based on either on classical photodiodes or in image sensors, known as Optical Camera Communications. The avant-garde applications of this technology have been studied focusing on three possible use scenarios: the traveler himself, in what we have called TAN (Tourist Area Network); the tourist facility, which includes not only the hotel but also leisure areas (theme parks, museums, natural protected areas) or services (restaurants, shopping areas, etc.); and the entire destination, which can be both the city or the territory where the tourist is received, within the paradigm of the Smart Tourist Destination (STD). In addition to the classic services based on radio frequency and wired broadband networks, these technologies will make it possible to meet the tourist’s challenging needs, the establishment, and the destination. Besides, they cover the services imposed by the new marketing services related to location or context and feed the big data systems used to study tourist behavior.

Optical wireless communications in outdoor scenarios are challenged by uncontrollable atmospheric conditions that impair the channel quality. In this paper, different optical camera communications (OCC) equipment are experimentally studied in the laboratory and the field, and a sub-pixel architecture is raised as a potential solution for outdoor wireless sensor networks (WSN) applications, considering its achievable data throughput, the spatial division of sources, and the ability of cameras to overcome the attenuation caused by different atmospheric conditions such as rain, turbulence and the presence of aerosols. Sub-pixel OCC shows particularly adequate capabilities for some of the WSN applications presented, also in terms of cost-effectiveness and scalability. The novel topology of sub-pixel projection of multiple transmitters over the receiver using small optical devices is presented as a solution using OCC that re-uses camera equipment for communication purposes on top of video-monitoring.

Visible light communications (VLC) technology is emerging as a candidate to meet the demand for interconnected devices’ communications. However, the costs of incorporating specific hardware into end-user devices slow down its market entry. Optical camera communication (OCC) technology paves the way by reusing cameras as receivers. These systems have generally been evaluated under static conditions, in which transmitting sources are recognized using computationally expensive discovery algorithms. In vehicle-to-vehicle networks and wearable devices, tracking algorithms, as proposed in this work, allow one to reduce the time required to locate a moving source and hence the latency of these systems, increasing the data rate by up to 2100%. The proposed receiver architecture combines discovery and tracking algorithms that analyze spatial features of a custom RGB LED transmitter matrix, highlighted in the scene by varying the cameras’ exposure time. By using an anchor LED and changing the intensity of the green LED, the receiver can track the light source with a slow temporal deterioration. Moreover, data bits sent over the red and blue channels do not significantly affect detection, hence transmission occurs uninterrupted. Finally, a novel experimental methodology to evaluate the evolution of the detection’s performance is proposed. With the analysis of the mean and standard deviation of novel K parameters, it is possible to evaluate the detected region-of-interest scale and centrality against the transmitter source’s ideal location.

Optical Camera Communication (OCC) systems have a potential application in microalgae production plants. In this work, a proof-of-concept prototype consisting of an artificial lighting photobioreactor is proposed. This reactor optimises the culture’s photosynthetic efficiency while transmitting on-off keying signals to a rolling-shutter camera. Upon reception, both signal decoding and biomass concentration sensing are performed simultaneously using image processing techniques. Moreover, the communication channel’s theoretical modelling, the data rate system’s performance, and the plant distribution requirements and restrictions for a production-scale facility are detailed. A case study is conducted to classify three different node arrangements in a real facility, considering node visibility, channel capacity, and space exploitation. Finally, several experiments comprising radiance evaluation and Signal-to-Noise Ratio (SNR) computation are performed at different angles of view in both indoor and outdoor environments. It is observed that the Lambertian-like emission patterns are affected by increasing concentrations, reducing the effective emission angles. Furthermore, significant differences in the SNR, up to 20 dB, perceived along the illuminated surface (centre versus border), gradually reduce as light is affected by greater dispersion. The experimental analysis in terms of scattering and selective wavelength attenuation for green (Arthrospira platensis) and brown (Rhodosorus marinus) microalgae species determines that the selected strain must be considered in the development of this system.

In this paper, the effect of channel conditions on the global behavior of a wireless Visible Light Communications (VLC) optical network are studied. It presents a system-level simulator that considers jointly a channel propagation model and the MAC mechanisms to have a realistic description of the network, even in situations where the emitted signal is heavily affected by reflections in any close surface or obstacle. The resulting platform also accurately evaluates both Line-Of-Sight (LOS) and Non-LOS (NLOS) contributions on each node and enables the effective use of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) schemes as defined by IEEE 802.15.7r1 standard, as well as allows a correct evaluation of lifelike problems such as the effect of hidden nodes. This work shows the necessity of accurately modeling VLC MAC layer performances, taking also into account the physical nature of visible light propagation in indoor scenarios.

This work presents a novel communications technology named Thermal Camera Communication (TCC), which is analogous to Optical Camera Communication (OCC). Thermographic cameras and Peltier cells are proposed as receiver and transmitter, respectively, changing completely their usual field of application. Furthermore, a comprehensive characterization of the Peltier–Thermal camera pair is carried out, presenting their bandwidth, achievable data rate under On-Off-Keying (OOK) modulation, noise characteristics, and energy efficiency. A comparison against the current state-of-the-art OCC technology is also provided, showing that TCC is a promising technology suitable for sensor networks. The thorough analysis of TCC performed in this work shows that commercial Peltier cells can be re-thought under a communications viewpoint in order to improve their performance. This novel communication technology can be applied in environments such as the access to public transportation or buildings due to the new health emergency situation. The use of thermographic cameras will become massive and dual measurement and communication purposes could be considered for applications such as sensor networks, using a yet unexploited wavelength range.

As our understanding of soil biology deepens, there is a growing demand for investigations addressing microbial processes in the earth beneath the topsoil layer, called subsoil. High clay content in subsoils often hinders the recovery of sufficient quantities of DNA as clay particles bind nucleic acids. Here, an efficient and reproducible DNA extraction method for 200 mg dried soil based on sodium dodecyl sulfate (SDS) lysis in the presence of phosphate buffer has been developed. The extraction protocol was optimized by quantifying bacterial 16S and fungal 18S rRNA genes amplified from extracts obtained by different combinations of lysis methods and phosphate buffer washes. The combination of one minute of bead beating, followed by ten min incubation at 65°C in the presence of 1 M phosphate buffer with 0.5% SDS, was found to produce the best results. The optimized protocol was compared with a commonly used cetyltrimethylammonium bromide (CTAB) method, using Phaeozem soil collected from 60 cm depth at a conventional agricultural field and validated on five subsoils. The reproducibility and robustness of the protocol was corroborated by an interlaboratory comparison. The DNA extraction protocol offers a reproducible and cost-effective tool for DNA-based studies of subsoil biology.

In recent years, there has been a remarkable advance in monitoring technologies in many environments, be they urban or rural. These technologies, included in the Internet of Things (IoT) domain, allow remote control and acquisition of data from sensors for their subsequence analysis. All these systems are based on the interaction between sensors and actuators. To achieve this goal, it is necessary to provide a very high level of connectivity between the devices, especially as far as wireless systems are concerned. In this sense, there is a great variety of standards in the market of communication networks oriented to this end. One of the biggest challenges today is to allow inter-operability between these different technologies in order to homogenize this field. In addition to this, it is intended to introduce new communication techniques that can provide certain additional advantages to those already existing. The main idea is the creation of a cellular network where radiofrequency and optical technologies coexist, and whose link with the rest of the world is through long-range and low-consumption wireless technologies. The center of each cell, that is the lighting system, can be powered using solar panels, as can the existing systems in the market. The objective is that these panels are capable of providing the necessary energy to the rest of the necessary systems.

Visible Light Communications (VLC) is a cutting edge technology for data communication that is being considered to be implemented in a wide range of applications such as Inter-vehicle communication or Local Area Network (LAN) communication. As a novel technology, some aspects of the implementation of VLC have not been deeply considered or tested. Among these aspects, security and its implementation may become an obstacle for VLCs broad usage. In this article, we have used the well-known Risk Matrix methodology to determine the relative risk that several common attacks have in a VLC network. Four examples: a War Driving, a Queensland alike Denial of Service, a Preshared Key Cracking, and an Evil Twin attack, illustrate the utilization of the methodology over a VLC implementation. The used attacks also covered the different areas delimited by the attack taxonomy used in this work. By defining and determining which attacks present a greater risk, the results of this work provide a lead into which areas should be invested to increase the safety of VLC networks.

In this work, a new Time Difference of Arrival (TDoA) scheme for distance measurement based on Optical Camera Communication (OCC) systems is proposed. It relies on the use of optical pulses instead of radio-frequency signals as the time reference triggers, and the introduction of a rolling shutter camera, whose characteristics allows substituting the timer modules used in conventional TDoA techniques by image processing of the illuminated area in the picture. This processing on the camera’s images provides time measurements and implies and specific analysis, which is presented in this work. The system performance and properties, such as resolution and range, mainly depends on the camera characteristics, such as the frames capture rate and the image quality. This new technique is suitable to be implemented in smartphones or other Commercial Off-The-Shelf (COTS) devices equipped with a camera and speakers.

The security and privacy provided by Visible Light Communication (VLC) technologies is an area that has been slightly addressed due to the misconception that, since light does not go through solid objects like walls, VLC-based communications cannot be eavesdropped on by outside observers. As an upcoming technology, VLC is expected to be used in multiple environments were, due to radio frequency RF overuse or limitations, RF solutions cannot or should not be employed. In this work, we study the eavesdropping characteristics of a VLC-based communication. To evaluate these concerns, a two-step process was followed. First, several simulations of a standardly used scenario were run. Later on, experimental tests were performed. Following those tests, the results of the simulations and the experimental tests were analyzed. The results of these simulations and tests seemed to indicate that VLC channels can be eavesdropped on without considerable difficulties. Furthermore, the results showed that sniffing attacks could be performed from areas outside the expected coverage of the VLC infrastructure. Finally, the use of the simulation such as the one implemented in this work to recognize places from which sniffing is possible helps determine the risk for eavesdropping that our VLC-based network has.

Due to the massive insertion of embedded cameras in a wide variety of devices and the generalized use of LED lamps, Optical Camera Communication (OCC) has been proposed as a practical solution for future Internet of Things (IoT) and smart cities applications. Influence of mobility, weather conditions, solar radiation interference, and external light sources over Visible Light Communication (VLC) schemes have been addressed in previous works. Some authors have studied the spatial intersymbol interference from close emitters within an OCC system; however, it has not been characterized or measured in function of the different transmitted wavelengths. In this work, this interference has been experimentally characterized and the Normalized Power Signal to Interference Ratio (NPSIR) for easily determining the interference in other implementations, independently of the selected system devices, has been also proposed. A set of experiments in a darkroom, working with RGB multi-LED transmitters and a general purpose camera, were performed in order to obtain the NPSIR values and to validate the deduced equations for 2D pixel representation of real distances. These parameters were used in the simulation of a wireless sensor network scenario in a small office, where the Bit Error Rate (BER) of the communication link was calculated. The experiments show that the interference of other close emitters in terms of the distance and the used wavelength can be easily determined with the NPSIR. Finally, the simulation validates the applicability of the deduced equations for scaling the initial results into real scenarios.

Distance estimation plays an important role in location-based services, which has become very popular in recent years. In this paper, a new short range cricket sensor-based approach is proposed for indoor location applications. This solution uses Time Difference of Arrival (TDoA) between an optical and an ultrasound signal which are transmitted simultaneously, to estimate the distance from the base station to the mobile receiver. The measurement of the TDoA at the mobile receiver endpoint is proportional to the distance. The use of optical and ultrasound signals instead of the conventional radio wave signal makes the proposed approach suitable for environments with high levels of electromagnetic interference or where the propagation of radio frequencies is entirely restricted. Furthermore, unlike classical cricket systems, a double-way measurement procedure is introduced, allowing both the base station and mobile node to perform distance estimation simultaneously.