The performance of the underwater optical wireless communication (UOWC) system is highly affected by seawater´s inherent optical properties and the solar radiation from sunlight, especially for a shallow environment. The multipath effect and degradations in signal-to-noise ratio (SNR) due to absorption, scattering, and ambient noises can significantly limit the viable communication range, which poses key challenges to its large-scale commercial applications. To this end, this paper proposes a unified model for underwater channel characterization and system performance analysis in the presence of solar noises utilizing a photon tracing algorithm. Besides, we developed a generic simulation platform with configurable parameters and self-defined scenarios via MATLAB. Based on this platform, a comprehensive investigation of underwater channel impairments was conducted including temporal and spatial dispersion, illumination distribution pattern, and statistical attenuation with various oceanic types. The impact of ambient noise at different operation depths on the bit error rate (BER) performance of the shallow UOWC system was evaluated under typical specifications. Simulation results revealed that the multipath dispersion is tied closely to the multiple scattering phenomenon. The delay spread and ambient noise effect can be mitigated by considering a narrow field of view (FOV) and it also enables the system to exhibit optimal performance on combining with a wide aperture.
Abstract
This study presents the effects of Tx./Rx. pointing errors on the performance efficiency of local area optical wireless communication networks. The received signal power and max Q factor are measured in the presence of vertical-cavity surface-emitting lasers (VCSELs) bias current and modulation current at maximum propagation distance for the wireless network. The signal is enhanced with increasing of bias and modulation peak currents of the VCSEL device. The optimum received power and max. Q factor is also examined at Tx./Rx. the pointing error of 0.1 mrad and propagation reach of 5 km at available bit rates transmission of 10 Gb/s.
AbstractOptical wireless communication (OWC) systems also known as Free space optics (FSO) are capable of providing high channel bandwidth, high data transmission rates, low power consumption, and high security. OWC links are being considered in different applications such as inter-satellite links, terrestrial links, and inter-aircraft communication links. This paper investigates the impact of different system parameters such as transmission power level, operating wavelength, transmitter pointing error angle, bit transmission rate, atmospheric attenuation, antenna aperture diameter, geometric losses, the responsivity of the photodetector, and link range on the performance of inter-aircraft optical wireless communication link.
AbstractThis paper investigates the impact of various parameters on the performance of inter-aircraft optical wireless communication (IaOWC) link. Also, an improved performance analysis of a 2.5 Gbps IaOWC link using an array of photodetectors at the receiver terminal has been reported. The results show an increase in the SNR and total power of the received signal at a link distance of 100 km by deploying a photodetector array at the receiver terminal.
AbstractThis work investigates the feasibility of terrestrial Optical wireless communication links under tropical and subtropical regions which are characterized by high precipitation. The impact of rain on propagating optical radiation is observed under controlled rainfall conditions using a laboratory testbed. Link degradation in terms of rain specific attenuation (RSA) is calculated experimentally and using known empirical models. A worst case analysis in terms of fade margin is carried out using measured and recorded data from Indian Meteorological Center to estimate the free space link feasibility for Indian tropical/subtropical climates.
In metropolitan communication infrastructures a revolutionary technique is emerge known as terrestrial optical wireless communication (OWC), which makes a high-rise building connection is possible. Even with this solution, there are many other problems like the influence of haze and fog in the propagation channel which obstruct and scatter OWC propagation light and consequently led to a big attenuation, due to propagate in temporal, angular and spatial of the light signal. Not to mention the minimum visibility that discourages the implementation of the pointing errors (PE) and tracking system. This present work aims to analyze the interrelation between multiple scattering (dense fog, heavy fog, light fog, heavy haze and light haze) and receiver PE under modified duo-binary return-to-zero (MDRZ) system. We found that PE caused by beam swag is the main controlling factor and industriously minimize the link margin, signal-to-noise ratio (SNR), and raise the bit error rate (BER) when there is an increasing the turbulence strength and the track length. We recommended to guarantee transmitter– receiver alignment by installing a variable field of view (FOV) receiver (a tracking system) to overcome the scattering impact of the fog that make render urban laser communication effective in the presence of PE.
Performance Analysis and Design Considerations of the Shallow Underwater Optical Wireless Communication System with Solar Noises Utilizing a Photon Tracing-Based Simulation Platform
