Availability analysis of terrestrial free space optical (FSO) link using visibility data measured in tropical region

Haze and rain are the most impairments factors to free space optical (FSO) links. These weather conditions limit the visibility, and thereby causes high attenuation of the optical signal. This high attenuation reduces the availability performance of the FSO link. This study evaluates the performance of a terrestrial FSO link under tropical climate conditions. The performance analysis is evaluate over 5 km link distance. The cumulative distribution function (CDF) of the received signal to noise ratio (SNR) is used to study the outage performance of the FSO link under haze conditions. The performance analysis is based on three years measured visibility data in Malaysia. Based on the statistical analysis, link availability of 99.99% can be achieved for 37.44 dB SNR over 1 km link distance. Carrier class availability “five nine” can be achieved for 20 dBm transmission power using 1550 nm wavelength

Availability assessment of free-space-optics links with rain data from tropical climates

Rainfall in tropical environments acts as a dominant parameter for estimating the availability of free-space optics (FSO). Long fades are caused by precipitation in particular heavy rains, and this precipitation increases atmospheric attenuation due to rain and reduces the availability of optical power from FSO links. In this paper, the link availability of an FSO system is estimated under the impact of rain in a tropical climate. The influence of rain on the propagation of FSO signal is investigated based on experimental and statistical analyses of rain-rate measurements under tropical conditions. Rain-rate data are measured in Malaysia for three years and used to estimate the availability of FSO links. Models developed in Malaysia are used to predict atmospheric attenuation due to rain. Long-term statistical measurements of rain data can enable good estimation of link availability. Based on the prediction model and measured rain-rate data, the FSO link budget is analyzed, and the link availability as a function of distance is predicted. Carrier class availability limits the FSO link to a few hundred meters only, whereas enterprise class availability can exceed FSO links over a few kilometers long

Availability analysis of terrestrial free space optical link under the impact of rain condition

Availability is one of the main factors to measure the QoS of any telecommunication networks. An accurate availability prediction for Free Space Optical link of carrier class grade is needed. In tropical areas, rain is the most dominant factor affecting the FSO link availability. In this paper, the effect of rain attenuation on the availability of FSO links is analyzed by examining the impact distance of different FSO systems. As the rain attenuation of FSO is independent of wavelength, the analysis of rain attenuation will be based on rain intensity. ITU-R (Carbonneau and Japan) models have been used for the analysis. From the results; Carrier class availability with good enough resolution for estimated availability can be predicted. This paper provides recommendations to FSO researchers in general and local telecom service provider in particular about possible availability figures that can be useful for deployment of FSO link as a last mile solution, back-up for fiber optic and other applications

Solvent-Free Biginelli Reactions Catalyzed by Hierarchical Zeolite Utilizing a Ball Mill Technique: A Green Sustainable Process

A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs) derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing of solvent was applied. The hierachical zeolite catalyst (MFI27_6) showed high yield (86%–96%) of DHPMs in a very short time (10–30 min). The recyclability of the catalyst for the subsequent reactions was examined in four subsequent runs. The catalyst was shown to be robust without a detectable reduction in catalytic activity, and high yields of products showed the efficient protocol of the Biginelli reactions

Machine Learning (ML) assisted Edge security framework on FPGAs

Edge computing (EC) is an act of bringing computational and storage capability near data sources. It helps to reduce response times and bandwidth requirements. However, the rapid proliferation of edge devices has expanded the attack surface and opportunity for adversaries to penetrate corporate networks. The limited computational abilities of edge devices and the heterogeneous nature of communication protocols further increase the security challenges of EC. Also, the trustworthiness of hardware devices is challenged due to security and privacy threats like trojan insertion, IP cloning, and hardware counterfeits. The application of Machine Language (ML) models in the edge computing paradigm creates a distributed intelligence architecture. Also, Field Programmable Gate Arrays (FPGAs) can exploit Physical Unclonable Functions (PUFs) characteristics to generate and store authentication keys. The PUF structure deployed with ML models in the edge layer can learn its complex input-output mapping from the Challenge and Response pairs (CRPs) to identify the suspicious and unknown responses. This article discusses the security and privacy issues in various layers of the EC architecture and proposes intrusion detection systems through the integration of FPGA-based edge sever and ML models. A PUF-assisted ML framework of the intrusion detection system is proposed to authenticate and detect potential attacks on the network

Tokens Shuffling Approach for Privacy, Security, and Reliability in IoHT under a Pandemic

Privacy and security are unavoidable challenges in the future of smart health services and systems. Several approaches for preserving privacy have been provided in the Internet of Health Things (IoHT) applications. However, with the emergence of COVID-19, the healthcare centers needed to track, collect, and share more critical data such as the location of those infected and monitor social distancing. Unfortunately, the traditional privacy-preserving approaches failed to deal effectively with emergency circumstances. In the proposed research, we introduce a Tokens Shuffling Approach (TSA) to preserve collected data’s privacy, security, and reliability during the pandemic without the need to trust a third party or service providers. TSA depends on a smartphone application and the proposed protocol to collect and share data reliably and safely. TSA depends on a proposed algorithm for swapping the identities temporarily between cooperated users and then hiding the identities by employing fog nodes. The fog node manages the cooperation process between users in a specific area to improve the system’s performance. Finally, TSA uses blockchain to save data reliability, ensure data integrity, and facilitate access. The results prove that TSA performed better than traditional approaches regarding data privacy and the performance level. Further, we noticed that it adapted better during emergency circumstances. Moreover, TSA did not affect the accuracy of the collected data or its related statistics. On the contrary, TSA will not affect the quality of primary healthcare services

Tropical Terrestrial Free Space Optical Link Performance Analysis

Free Space Optical (FSO) has a very good potential alternative solution to Radio Frequency (RF) to provide high terrestrial wireless communication. In tropical region, the only drawback of FSO is atmospheric attenuation due to mainly haze and rain. This study investigates the performance of FSO system over link distances that ranges between 9 km to 12 km as the average visibility in Kuala Lumpur, Malaysia is 10 km. Two models used to predict the atmospheric attenuation, namely Kruse model and modified Kruse model. These models are valid to predict the haze attenuation for visibilities that range between 9 to 12 km. The modified/corrected Kruse model shows some limitations in the prediction of haze attenuation over longer wavelength. However, the study indicates that attenuation due to haze is low, while air quality in Kuala Lumpur, Malaysia is acceptable. As the size of haze particles varies from 0.01 to 1 µm, the longer wavelength is preferable as 1550 nm to enhance FSO performance compared to 850 nm and 600 nm wavelengths. Thus, the longer wavelength is the optimal choice to enhance the FSO performance as it caused low scattering

A proposed rain attenuation prediction method for free space optical link based on rain rate statistics

Free Space Optics technology has gained acceptance in telecommunication industry mostly in enterprise campus network. However in tropical regions, rainfall is the dominant factor that degrades the FSO link performance and its availability. In this paper, a method is proposed to estimate the total path attenuation due to rain for Free Space Optical communication links for all percentage of availabilities and any path length. Path length reduction factor for FSO has been derived using reduction factors models developed for microwave under measurement in tropical climate. Regression analysis has been applied and model is derived using best fit curve. Comparison between derived and measured reduction factors has been made for validation. Derived reduction factor seems to have strong agreement with both models which were derived based on measurements. This method can provide estimation of total path rain attenuation for FSO for all percentage of time with any path lengths

Haze impact on availability of terrestrial free space optical link

Free Space Optics is a promising optical wireless technology in broadband networks. It uses laser as a medium of transmission between two transceivers. In tropical climate, haze is one of the weather phenomenons which reduce the visibility. Low visibility increases atmospheric attenuation and reduce the availability of optical signals for free space optics (FSO) links. In this paper, the effect of atmospheric attenuation due to haze on free space optical link in tropical climate has been demonstrated. The analysis based on one year measured visibility data in Malaysia. Predicted attenuation varies with different wavelengths. Thus, two wavelengths were considered. The predicted atmospheric attenuation was compared across the two wavelengths. Measured visibility data and predicted attenuation were used to estimate the link availability of free space optical links. From the results higher wavelength has lower attenuation compare with lower wavelength. This paper indicates useful information for the deployment of FSO link in tropical climate