Ahmed Basahel

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.

Carrier Class Availability Prediction for Hybrid FSO/RF System in Heavy Rainfall Regions Based on ITU-R Models

 Abstract—Availability is considered as the main parameter of evaluating a Hybrid FSO/RF link quality. An accurate carrier class availability prediction of Hybrid FSO/RF is needed. In tropical regions, among different weather influences, rain plays a major role. Precipitation decrees are available for frequencies above 10 GHz. In this paper we will analyze the effect of rain on Hybrid FSO/RF to find the optimum operating frequency to back-up the FSO link besides tradeoff between speed of RF and link availability of FSO in tropical environment; we will also provide better prediction of link availability. ITU-R specific rain attenuation of FSO and RF models has been used for the analysis. From the results, a 30 GHz and below are suggested to be used as a back-up of FSO link to achieve carrier grade availability under the impact of rain.

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.

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.

Availability Prediction Methods for Terrestrial Free-Space-Optical Link Under Tropical Climate

Received Jan 15, 2018 Revised Mar 14, 2018 Accepted Mar 30, 2018 Blood veins detection process can be cumbersome for nurses and medical practioners when it comes to special overweight type of patients. This simple routine procedure can lead the process into an extreme calamity for these patients. In this paper, we emphasized on a process for the detection of the vein in real time using the consecrations of Matlab to prevent or at least reduce the number of inescapable calamity for patients during the infusion of a needle by phlebotomy or doctor in everyday lives. Hemoglobin of the blood tissues engrossed the Near Infrared (NIR) illuminated light and Night vision camera is used to capture the scene and enhance the vein pattern clearly using Contrast Limited Adaptive Histogram Equalization (CLAHE) method. This simple approach can successfully also lead to localizing bleeding spots, clots from stroke ... etc among other things.

Outage analysis of terrestrial free space optical (FSO) link using measured visibility data in Malaysia

Haze and rain are the most important impairment factors at the tropical region that affect the performance of free space optical (FSO) links; they limit the visibility which directly reduces the link availability. Lower visibility generates high attenuation of optical signal resulting in reducing the link availability of the optical signal. In this project, availability performance is evaluated by establishing a one-year measured visibility data in Malaysia. Based on one measurement of visibility, link availability of 99.99% can be achieved over a link distance of 1 Km for 37.44 dB SNRHaze and rain are the most important impairment factors at the tropical region that affect the performance of free space optical (FSO) links; they limit the visibility which directly reduces the link availability. Lower visibility generates high attenuation of optical signal resulting in reducing the link availability of the optical signal. In this project, availability performance is evaluated by establishing a one-year measured visibility data in Malaysia. Based on one measurement of visibility, link availability of 99.99% can be achieved over a link distance of 1 Km for 37.44 dB SNR

Effect of Rain a Haze on Availability of Terrestrial Free Space Optical Link under Tropical Weather Conditions

Availability is a major concern to measure the QoS of Free Space Optical (FSO) communication link. In tropical areas, rain is the most dominant factor affecting the FSO link availability, whereas haze has no significant impact on FSO link availability compare to rain. In this paper, availability assessment of FSO was examined based on predicted atmospheric attenuations due to rain and haze. The predicted atmospheric attenuations due to rain and haze were obtained using rain rate (mm/hr) and visibility (km) data measured in Malaysia. The effect of individual weather phenomena was analyzed and availability performance of FSO was evaluated. Combine effect of both rain and haze was also demonstrated using cumulative distribution function (CDF) of both atmospheric attenuations due to rain and haze. This study 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 system over one kilometer link distance.