A comprehensive study of outdoor visible light communication (VLC) under snow and rain effects has been conducted in this paper. This paper analyzes the expected rain attenuation of Marshal, Carbonneau, and Japan models at different precipitation levels. Snow attenuation is measured in wet and dry situations at various precipitation levels as well. Therefore, a full comparison is carried out for different attenuation effects on certain outdoor VLC design characteristics such as the maximum signal-to-noise ratio (SNR), optical power received, bit error rate (BER), and maximum coverage area. VLC with various modulation techniques is considered. The ON–OFF Keying (OOK), L-Pulse Position Modulation (L-PPM), Inverse L-Pulse Position Modulation (I-L-PPM), and Subcarrier Binary Phase-Shift Keying (SC-BPSK) are investigated. The simulation results show a considerable difference in the information received under different weather conditions depending on the type of modulation scheme used. The simulation has been done on a two-lane road, and a green traffic light-emitting diode (LED) with a wavelength of 505 nm is used as a transmitter. A non-imaging concentrator coupled with a photodetector is considered to be a cost-effective receiver.

In this paper, the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system is investigated utilizing a single photodiode (SPD) detection technique. The proposed system uses enhanced double weight (EDW) codes as signature codes with three simultaneous users to overcome both phase-induced intensity noise (PIIN) and multiple access interference (MAI). In addition, a dispersion compensating fiber (DCF) is used in order to decrease the group velocity dispersion (GVD) caused in the single mode fiber. An erbium-doped fiber amplifier (EDFA) is used to overcome the attenuation. The use of both DCF and EDFA leads to an appreciable enhancement in the system performance. The system performance is evaluated through its bit error rate (BER), Q-factor, and received power. A comparison between the EDW codes and modified double weight (MDW) codes on the SAC-OCDMA system is demonstrated. Simulation is carried out through Optisystem ver. 7. The simulation results show that: (a) using an avalanche photodiode (APD) over PIN photodiode allows data transmission over longer distances; (b) the use of DCF improves the system BER;(c) using MDW codes gives better BER than using EDW codes.

This paper aims to extend the limited bandwidth of phosphorescent white LEDs for a multiple-input single-output (MISO) visible light communication (VLC) system. A proposed LED arrangement model is presented, resulting in improved results as compared to those previously discussed in the literature. In this paper, the impact of the receiver field of view (FOV) angle, the LED transmission angle, and the number of LED arrays used on the transmission are studied at different speeds. The system performance is measured by the signal to noise ratio (SNR) and the corresponding bit error rate (BER) at different data rates. The obtained results show that the proposed model is able to improve the illumination uniformity across the room with a higher SNR using the same number of LEDs in the investigated indoor environment. The paper also introduces a pre-equalization circuit in the transmitter end in order to extend the limited bandwidth of the used white LEDs. This bandwidth extension using the proposed circuit results in an increased data rate with the aid of a blue filter. A number of experiments are executed to optimize the key parameters for maximum bandwidth enhancement. The proposed circuit offers 28% bandwidth enhancement over the most recent study in this area while eradicating the BER at 200 Mb/s when compared to un-equalized LED circuits.