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In this study, the effects of the use of photodiode arrays in visible light communication systems on communication performance are investigated. In the optical transmitter part, there are new generation power LEDs with different wavelengths and lenses with different angles; in the optical receiver part, there is a sensor array consisting of photosensitive PIN photodiodes in the visible light band, a comparator circuit with an opamp and an average voltage tracking block. With the designed communication system, the effects of the magnitude of the LED current, the value of the lens angle, the distance between the optical transmitter and the optical receiver on the data transfer rate were investigated. [ABSTRACT FROM AUTHOR]

In this work we implemented a visible light communication system with external modulation through a $1.5 USD light valve, a logarithmic scale analog light sensor, a $5 USD Fresnel lens, a 12 V LED operating continuously, and 2 Raspberry Pi 3. This work is an initiative to directly exploit sunlight as a radiation source to complement VLC systems with a low implementation cost. The light valve allowed transmitting data at a rate of 100 bps which suggests an application scenario such as wireless sensor networks and in general for the Internet of Things (IoT). Since there is not much room in the radio spectrum to accommodate new wireless communication services and technologies, VLC systems promise to be a great complement to conventional wireless access networks to balance the traffic load present when there is a massive connection of devices in the IoT paradigm. [ABSTRACT FROM AUTHOR]

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VLC systems (Visible Light Communication), use LEDs (Light Emitting Diodes) as transmitters and photodetectors as receivers. This is because its high speed of response and they are useful for wireless optical communications. There are different kind of photodetectors, the most common are the PN, PIN and APD photodiodes. In this dissertation we present the characterization of an LTF (Light to Frequency) TSL235R-LF Sensor which consists of a PIN type photodiode, and a current to frequency converter. This device generate a square signal with constant amplitude, 50% duty cycle and its frequency is a function of the incident optical power. In our experiment, we use as a light source an RGB LED for transmitting and we notice that the generated frequency by the LTF increases or decreases linearly, depending on the incident optical power. We noticed that, for the same optical powers detected, with a different wavelength (red, green and blue), the output frequency of the LTF sensor is different. This fact is of great interest in order to distinguish symbols in CSK modulation formats on VLC systems. [ABSTRACT FROM AUTHOR]

The high wireless requirements in access, capacity and security demanded by today's society together with the great congestion of the radio spectrum has led to looking for new technological solutions such as Light Fidelity (Li-Fi). This paper shows the design and implementation of a Li-Fi communications system within an indoor environment used the optical OFDM modulation technique with asymmetric clipping (ACO-OFDM) through MATLAB software. System performance is analyzed in terms of bit error rate (BER) and bit to noise power ratio (Eb/No) taking into account receiver position, QAM modulation order and transmission rate. The results show that the performance of the system depends directly on the position of the receiver, in addition to high transmission rates the multipath degrades the performance of the system. [ABSTRACT FROM AUTHOR]

Among the most innovative and promising technologies at present time appears without place to doubts Li-Fi (Light-Fidelity), a technology based on high-speed data transmission using visible or infrared light, a complement to Wi-Fi based solutions for broadband access in diverse indoor or ad-hoc environments. The estimation of wireless optical channel parameters in such environments is of great importance for the prediction and optimization of such systems. Traditionally efforts have been made in this direction: the simplified analysis of empty scenarios, that is, devoid of furniture or obstacles of any kind typically present in offices and working environments where Li-Fi access systems would be deployed. The present work proposes the application of a general model of simulation of the propagation of optical signals in the wireless channel, developed previously by the authors and based on Monte Carlo ray-tracing and the use of bidirectional reflectance functions (TRM-B model), applied to enriched virtual environments, that is to say, digitally synthesized 3D environments that recreate with more precision the characteristics of real deployment scenarios, which allows a more accurate estimation of the channel parameters and its performance for Li-Fi systems. [ABSTRACT FROM AUTHOR]