Browsing by Author "Touati, F."

Now showing 1 - 4 of 4

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On the effects of combined atmospheric fading and misalignment on the hybrid FSO/RF transmission
(The Optical Society, 2016) Touati, A.; Abdaoui, A.; Touati, F.; Uysal, Murat; Bouallegue, A.; Electrical & Electronics Engineering; UYSAL, Murat
Free-space optical (FSO) communication is known for its various impairments such as atmospheric turbulence and misalignment fading. In this paper, we study the performance of an FSO link operating under combined path loss and atmospheric and misalignment fadings. We derive a closed-form expression for the bit error rate (BER) of the FSO link in such conditions when the on–off keying (OOK) modulation is employed and when the fluctuations of the received signal are modeled by Gamma–Gamma distribution. In addition, we evaluate the effects of the combined fadings on the outage probability of the FSO link for different strengths of turbulence and pointing errors. Furthermore, we investigate the advantages of combining radio frequency (RF) with FSO to form hybrid FSO/RF systems. The RF link is based on 16 quadrature amplitude modulation (16-QAM) and on Rician channel fading. We study the performance of the hybrid FSO/RF system in terms of outage probability and BER and find that the hybrid FSO/RF system can overcome the weaknesses of FSO links, which are sensitive to atmospheric variations and misalignment fading.
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On the effects of temperature on the performances of FSO transmission under qatar's climate
(IEEE, 2017-11-14) Touati, A.; Abdaoui, A.; Touati, F.; Uysal, Murat; Bouallegue, A.; Electrical & Electronics Engineering; UYSAL, Murat
Strong atmospheric turbulence can highly affect the free space optical (FSO) link. In fact, the strength of turbulence is depending on weather factors where the temperature is considered as the main parameter increasing these turbulences. In this work, an experimental investigation of the effect of Qatar's harsh climate on FSO link in term of packet ratio delivery (PDR) is carried out. Two FSO transceivers, operating June at 1550 nm for 600 m link distance, have been used. Based on Bendersky, Kopeika and Blaunstein (BKB) model and on the measured weather factors we tried to characterise the strength of turbulences under Qatar climate.
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Outage analysis of hybrid FSO/RF systems based on finite-state Markov Chain modeling
(IEEE, 2014) Kazemi, Hossein; Uysal, Murat; Touati, F.; Electrical & Electronics Engineering; UYSAL, Murat; Kazemi, Hossein
In this paper, we analyze the outage probability of a hybrid free-space optical/radio-frequency (FSO/RF) communication system with soft-switching. In soft-switching approach, either one of the links or both links can be active relying on their availabilities. We first model the link selection required for soft-switching between the FSO and RF channels in different weather conditions by a finite-state Markov chain (FSMC) process. Then, based on the proposed model, we derive a closed-form outage probability expression in terms of various system and weather condition parameters. Numerical results are provided to present the outage performance under various weather conditions.
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Outage performance of multi-hop hybrid FSO/RF communication systems
(IEEE, 2015) Kazemi, H.; Uysal, Murat; Touati, F.; Haas, H.; Electrical & Electronics Engineering; UYSAL, Murat
In this paper, five scenarios are considered for the realization of a multi-hop hybrid free-space optical/radio frequency (FSO/RF) communication system with decode-and-forward (DF) relaying, and analytical outage probability expressions are derived. The scenarios have a different number of FSO and RF links. The aim is to identify an optimum scenario to effectively improve the end-to-end reliability of the multi-hop hybrid FSO/RF system. Outage performance is investigated for the scenarios under various weather conditions through numerical examples. It is identified that for a given link distance the end-to-end outage probability is minimized when using a hybrid FSO/RF link between every two successive nodes of the multi-hop system, and this requires the maximum number of FSO and RF links to be deployed.