In this work, solid flexible polymer blend electrolytes (PBE) composed of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) with different amounts of sodium thiocyanate (NaSCN) salt mixed in double-distilled water (solvent) are prepared via solution casting method. The obtained films are characterized using several techniques. The study of the surface morphology of the polymer blend salt complex films via the POM technique reveals the presence of amorphous regions due to the NaSCN effect. FTIR spectra studies confirm the complex formation between PVA, PVP, and NaSCN. The addition of 20 wt% NaSCN salt in the composition PVA: PVP (50:50 wt%) polymer blend matrix leads to an increase in the number of charge carriers and thus improves the ionic conductivity. The ionic conductivity of each polymer blend electrolyte was studied using the electrochemical impedance spectroscopy (EIS) method. The highest room temperature ionic conductivity of 8.1 × 10⁻⁵ S/cm S cm⁻¹ is obtained for the composition of PVA: PVP (50:50 wt%) with 20 wt% NaSCN. LSV test shows the optimized ion-conducting polymer blend electrolyte is electrochemically stable up to 1.5 V. TNM analysis reveals that 99% of ions contribute for the conductivity against 1% of electrons only in the highly conductive polymer electrolyte PVA: PVP (50:50 wt%) + 20 wt% NaSCN. A supercapacitor device was fabricated using the optimized ion-conducting polymer blend film and graphene oxide (GO) coated electrodes. The GCD curve clearly reveals the behavior of an ideal capacitor with less Faradic process and low ESR value. The columbic efficiency of the GO-based system is found to be 100%, the GO-based electrode exhibits a specific capacitance of 12.15 F/g and the system delivers the charge for a long duration. The specific capacitance of the solid-state supercapacitor cell was found to be 13.28 F/g via the CV approach close to 14.25 F/g obtained with EIS data at low frequency.

The foundation of any smart city requires an innovative and robust communication infrastructure. Many research communities envision free-space optical communication (FSO) as a promising backbone technology for the services and applications provided by such cities. However, the channel through which the FSO signal travels is the atmosphere. Therefore, the FSO performance is limited by the local weather conditions. The variation in meteorological variables leads to variations of the refractive index along the transmission path. These index inhomogeneities (i.e., atmospheric turbulence) can significantly degrade the performance of FSO systems. Thus, a practical implementation of the FSO link must carefully consider the atmospheric turbulence effect. This paper aims to investigate the feasibility of FSO communication for NEOM, a promising smart city in Saudi Arabia. We study the effect of weather conditions on FSO links using the micrometeorology model, taking into account actual weather data. The FSO performance in winter and summer was compared in terms of the bit error rate, signal-to-noise ratio (SNR), link availability, and transmission distance. The study shows that the atmospheric turbulence strength is moderate and strong in winter and summer, respectively. The temperature has the biggest impact on the FSO system when compared to the other meteorological elements included in this study. Furthermore, at transmission distances less than 300 m, atmospheric turbulence does not significantly affect the FSO for the operating wavelength of 1550 nm. Furthermore, it has been shown that at transmission distances greater than 300 m, the SNR in summer is more than 18% higher than in winter. The findings of this research enable understanding of the effect of turbulence caused by NEOM weather on the FSO link, thus assisting engineers in establishing a reliable FSO backbone link by adjusting the relevant parameters.

There has been significant interest in free-space optical (FSO) communication by the research community in recent years. This is due to its high data rate, unlicensed spectrum, low cost, and immense security for FSO systems. Due to these advantages, FSO can have broader applications that extend from terrestrial to satellite communication. Atmospheric turbulence (AT) induced fading is a primary problem in the FSO link since it significantly impairs its performance. Atmospheric turbulence occurs due to the random variation of the air refractive index with time. Several statistical models are introduced to characterize the AT. The Log-normal (LN) model represents weak and moderate turbulence, and the Gamma-Gamma (G-G) model is employed for strong turbulence. These models are used with the effect of weather attenuation, geometric losses, and misalignment errors. One possible solution is channel coding, such as low-density parity-check (LDPC) codes. This paper proposed employing Weighted Bit Flipping (WBF) and Implementation Efficient Reliability Ratio Weighted Bit Flipping (IERRWBF) decoding techniques to improve FSO link performance. The results show a superior improvement in the bit error rate (BER) than the uncoded FSO system. In addition, the obtained results prove that the IERRWBF technique is more optimized than WBF from the point of the number of iterations, especially in weak and moderate turbulence FSO channels. In the calculation of decoders processing time, the WBF maintained lower decoding time than the IERRWBF technique, while in higher Eb/Nos, they have the same level. The same response for both techniques in the case of resultant throughput. Finally, both methods are evaluated from the point of convergence. IERRWBF technique achieved faster convergence than WBF in all FSO channels under study.

Several industrial and scientific underwater applications require high-speed wireless connectivity. Acoustic communications have low data rates and high latency, whereas attenuation in seawater severely limits radio frequency communications. Optical wireless communication is a promising solution, with high transmission rates (up to Gb/s) and little attenuation in water at visible wavelengths. This study explores the feasibility of white-LED-based underwater optical wireless communication (UWOC) by considering Red Sea parameters. High salinity is the most prominent attribute of the Red Sea that can affect underwater communication and requires investigation. Considering this, the received signal intensity fluctuation under increasing water salinity was experimentally investigated. In the same experiment, the impact of growing turbidity was tested, as it is the most influential parameter and tends to block the entire LED-based communication system with little increase. The experimental results show that the signals are affected less by salinity and more by turbidity but are found to be sufficiently strong to be used for communication in the Red Sea. Finally, it was concluded that a white LED is capable of sending data at the maximum possible salinity values of 40 g/L. However, the turbidity can significantly limit the transmission distance to less than 60 cm.

Smart cities like Neom require efficient and reliable transportation systems to support their vision of sustainable and interconnected urban environments. High-speed trains (HSTs) play a crucial role in connecting different areas of the city and facilitating seamless mobility. However, to ensure uninterrupted communication along the rail lines, advanced communication systems are essential to expand the coverage range of each base station (BS) while reducing the handover frequency. This paper presents the dual transceiver free space optical (FSO) communication system as a solution to achieve these objectives in the operational environment of HSTs in Neom city. Our channel model incorporates log-normal (LN) and gamma–gamma (GG) distributions to represent channel impairments and atmospheric turbulence in the city. Furthermore, we integrated the siding loop model, providing valuable insights into the system in real-world scenarios. To assess the system’s performance, we formulated the received signal-to-noise ratio (SNR) of the network under assumed fading conditions. Additionally, we analyzed the system’s bit error rate (BER) analytically and through Monte Carlo simulation. A comparative analysis with reconfigurable intelligent surfaces (RIS) and relay-assisted FSO communications shows the superior coverage area and efficiency of the dual transceiver model. A significant reduction of up to 76% and 99% in the number of required BSs compared to RIS and relay, respectively, is observed. This reduction leads to fewer handovers and lower capital expenditure (CAPEX) costs.