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Multihop Relaying Over IM/DD FSO Systems With Pointing Errors

Emna Zedini, Mohamed-Slim Alouini
2015 Journal of Lightwave Technology  
In this paper, the end-to-end performance of a multihop free-space optical system with amplify-and-forward channelstate-information-assisted or fixed-gain relays using intensity modulation with direct detection technique over Gamma-Gamma turbulence fading with pointing error impairments is studied. More specifically, novel closed-form results for the probability density function and the cumulative distribution function of the end-to-end signal-to-noise ratio (SNR) are derived in terms of the
more » ... 's H function. Based on these formulas, closed-form bounds for the outage probability, the average bit-error rate (BER) of on-off keying modulation scheme, the moments, and the ergodic capacity are presented. Furthermore, using the momentsbased approach, tight asymptotic approximations at high and low average SNR regimes are derived for the ergodic capacity in terms of simple elementary functions. The obtained results indicate that the overall system performance degrades with an increase of the number of hops. The effects of the atmospheric turbulence conditions and the pointing error are also quantified. All the analytical results are verified via computer-based Monte-Carlo simulations.
doi:10.1109/jlt.2015.2492244 fatcat:gjaacicyvzc3bd6pkiu5oabluq

On the Performance of Multihop Heterodyne FSO Systems With Pointing Errors

Emna Zedini, Mohamed-Slim Alouini
2015 IEEE Photonics Journal  
This paper reports the end-to-end performance analysis of a multihop freespace optical system with amplify-and-forward (AF) channel-state-information (CSI)assisted or fixed-gain relays using heterodyne detection over Gamma-Gamma turbulence fading with pointing error impairments. In particular, we derive new closed-form results for the average bit error rate (BER) of a variety of binary modulation schemes and the ergodic capacity in terms of the Meijer's G function. We then offer new accurate
more » ... mptotic results for the average BER and the ergodic capacity at high SNR values in terms of simple elementary functions. For the capacity, novel asymptotic results at low and high average SNR regimes are also obtained via an alternative moments-based approach. All analytical results are verified via computer-based Monte-Carlo simulations.
doi:10.1109/jphot.2015.2417867 fatcat:ngoor6u2qvb5nbrqtigzffbyaq

Performance of Multibeam Very High Throughput Satellite Systems Based on FSO Feeder Links with HPA Nonlinearity [article]

Emna Zedini, Abla Kammoun, Mohamed-Slim Alouini
2020 arXiv   pre-print
Due to recent advances in laser satellite communications technology, free-space optical (FSO) links are presented as an ideal alternative to the conventional radio frequency (RF) feeder links of the geostationary satellite for next generation very high throughput satellite (VHTS) systems. In this paper, we investigate the performance of multibeam VHTS systems that account for nonlinear high power amplifiers at the transparent fixed gain satellite transponder. Specifically, we consider the
more » ... d link of such systems, where the RF user link is assumed to follow the shadowed Rician model and the FSO feeder link is modeled by the Gamma-Gamma distribution in the presence of beam wander and pointing errors where it operates under either the intensity modulation with direct detection or the heterodyne detection. Moreover, zero-forcing precoder is employed to mitigate the effect of inter-beam interference caused by the aggressive frequency reuse in the user link. The performance of the system under study is evaluated in terms of the outage probability, the average bit-error rate (BER), and the ergodic capacity that are derived in exact closed-forms in terms of the bivariate Meijer's G function. Simple asymptotic results for the outage probability and the average BER are also obtained at high signal-to-noise ratio.
arXiv:2005.14218v1 fatcat:7lzswrwesneazk6fyemszsfkka

Unified Performance Analysis of Mixed Line of Sight RF-FSO Fixed Gain Dual-Hop Transmission Systems [article]

Emna Zedini, Imran Shafique Ansari, Mohamed-Slim Alouini
2014 arXiv   pre-print
In this work, we carry out a unified performance analysis of a dual-hop fixed gain relay system over asymmetric links composed of both radio-frequency (RF) and unified free-space optics (FSO) under the effect of pointing errors. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e. heterodyne detection and intensity modulation with direct detection (IM/DD)). In particular, we derive new
more » ... ed closed-form expressions for the cumulative distribution function, the probability density function, the moment generation function, and the moments of the end-to-end signal-to-noise ratio of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability, the higher-order amount of fading, and the average bit-error rate of a variety of binary modulations in terms of the Meijer's G function. Further, an exact closed-form expression for the end-to-end ergodic capacity for the Nakagami-m-unified FSO relay links is derived in terms of the bivariate G function. All the given results are verified via Computer-based Monte-Carlo simulations.
arXiv:1404.1269v1 fatcat:jb6otjzdvzg3rn2przsl4h5sd4

On the Performance Analysis of Dual-Hop Mixed FSO/RF Systems

Emna Zedini, Hamza Soury, Mohamed-Slim Alouini
2016 IEEE Transactions on Wireless Communications  
Zedini This paper is an extended version of work accepted for publication in the 12th International Symposium on Wireless Communication Systems (ISWCS'15) [25] . system capacity and throughput.  ... 
doi:10.1109/twc.2016.2524685 fatcat:5ib6cucgmvdqxjkec5gfywn5p4

Unified Statistical Channel Model for Turbulence-Induced Fading in Underwater Wireless Optical Communication Systems [article]

Emna Zedini, Hassan M. Oubei, Abla Kammoun, Mounir Hamdi, Boon S. Ooi,, Mohamed-Slim Alouini
2018 arXiv   pre-print
A unified statistical model is proposed to characterize turbulence-induced fading in underwater wireless optical communication (UWOC) channels in the presence of air bubbles and temperature gradient for fresh and salty waters, based on experimental data. In this model, the channel irradiance fluctuations are characterized by the mixture Exponential-Generalized Gamma (EGG) distribution. We use the expectation maximization (EM) algorithm to obtain the maximum likelihood parameter estimation of
more » ... new model. Interestingly, the proposed model is shown to provide a perfect fit with the measured data under all channel conditions for both types of water. The major advantage of the new model is that it has a simple mathematical form making it attractive from a performance analysis point of view. Indeed, we show that the application of the EGG model leads to closed-form and analytically tractable expressions for key UWOC system performance metrics such as the outage probability, the average bit-error rate, and the ergodic capacity. To the best of our knowledge, this is the first-ever comprehensive channel model addressing the statistics of optical beam irradiance fluctuations in underwater wireless optical channels due to both air bubbles and temperature gradient.
arXiv:1810.06314v1 fatcat:qnhtsd4i4fesfpbacbi2fj7m3q

Performance Analysis of Mixed Nakagami- $m$ and Gamma–Gamma Dual-Hop FSO Transmission Systems

Emna Zedini, Imran Shafique Ansari, Mohamed-Slim Alouini
2015 IEEE Photonics Journal  
In this paper, we carry out a unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency (RF) and unified free-space optical (FSO) links under the effect of pointing errors. Both fixed and variable gain relay systems are studied. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e., heterodyne detection and intensity modulation with
more » ... ect detection). In particular, we derive new unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability (OP), the higher order amount of fading, and the average bit error rate (BER) of a variety of binary modulations in terms of the Meijer's G function. Furthermore, an exact closed-form expression of the end-to-end ergodic capacity is derived in terms of the bivariate G function. Additionally, by using the asymptotic expansion of the Meijer's G function at the high-SNR regime, we derive new asymptotic results for the OP, the MGF, and the average BER in terms of simple elementary functions. Index Terms: Free-space optics (FSO), mixed RF/FSO systems, nakagami-m fading, atmospheric turbulence, pointing errors, outage probability (OP), bit error rate (BER), ergodic capacity, Meijer's G function. Channel and System Models We consider an asymmetric dual-hop amplify-and-forward relaying system where the source node S and the destination node D are communicating through an intermediate relay node R,
doi:10.1109/jphot.2014.2381657 fatcat:rnvu4fdfdfhcddcwv6vm33bpxa

Dual-Hop FSO Transmission Systems Over Gamma–Gamma Turbulence With Pointing Errors

Emna Zedini, Hamza Soury, Mohamed-Slim Alouini
2017 IEEE Transactions on Wireless Communications  
In this paper, we analyze the end-to-end performance of dual-hop free-space optical (FSO) fixed gain relaying systems under heterodyne detection and intensity modulation with direct detection techniques in the presence of atmospheric turbulence as well as pointing errors. In particular, we derive the cumulative distribution function (CDF) of the end-to-end signal-to-noise ratio (SNR) in exact closed-form in terms of the bivariate Fox's H function. Capitalizing on this CDF expression, novel
more » ... d-form expressions for the outage probability, the average bit-error rate (BER) for different modulation schemes, and the ergodic capacity of dual-hop FSO transmission systems are presented. Moreover, we present very tight asymptotic results for the outage probability and the average BER at high SNR regime in terms of simple elementary functions and we derive the diversity order of the considered system. By using dual-hop FSO relaying, we demonstrate a better system performance as compared to the single FSO link. Numerical and Monte-Carlo simulation results are provided to verify the accuracy of the newly proposed results, and a perfect agreement is observed.
doi:10.1109/twc.2016.2630680 fatcat:yom5hfypgbhrzf2ekoqmdjlavu

Performance Analysis of Dual-Hop Underwater Wireless Optical Communication Systems over Mixture Exponential-Generalized Gamma Turbulence Channels [article]

Emna Zedini, Abla Kammoun, Hamza Soury, Mounir Hamdi, Mohamed-Slim Alouini
2020 arXiv   pre-print
In this work, we present a unified framework for the performance analysis of dual-hop underwater wireless optical communication (UWOC) systems with amplify-and-forward fixed gain relays in the presence of air bubbles and temperature gradients. Operating under either heterodyne detection or intensity modulation with direct detection, the UWOC is modeled by the unified mixture Exponential-Generalized Gamma distribution that we have proposed based on an experiment conducted in an indoor laboratory
more » ... setup and has been shown to provide an excellent fit with the measured data under the considered lab channel scenarios. More specifically, we derive the cumulative distribution function (CDF) and the probability density function of the end-to-end signal-to-noise ratio (SNR) in exact closed-form in terms of the bivariate Fox's H function. Based on this CDF expression, we present novel results for the fundamental performance metrics such as the outage probability, the average bit-error rate (BER) for various modulation schemes, and the ergodic capacity. Additionally, very tight asymptotic results for the outage probability and the average BER at high SNR are obtained in terms of simple functions. Furthermore, we demonstrate that the dual-hop UWOC system can effectively mitigate the short range and both temperature gradients and air bubbles induced turbulences, as compared to the single UWOC link. All the results are verified via computer-based Monte-Carlo simulations.
arXiv:2007.03461v1 fatcat:n2gxo3wriffdrbv4cvnuj6ehgu

Throughput and Delay Analysis of HARQ With Code Combining Over Double Rayleigh Fading Channels

Ali Chelli, Emna Zedini, Mohamed-Slim Alouini, Matthias Patzold, Ilangko Balasingham
2018 IEEE Transactions on Vehicular Technology  
This paper proposes the use of hybrid automatic repeat request (HARQ) with code combining (HARQ-CC) to offer reliable communications over double Rayleigh channels. The double Rayleigh fading channel is of particular interest to vehicle-to-vehicle communication systems as well as amplify-andforward relaying and keyhole channels. This work studies the performance of HARQ-CC over double Rayleigh channels from an information theoretic perspective. Analytical approximations are derived for the
more » ... e capacity, the average number of transmissions, and the throughput of HARQ-CC. Moreover, we evaluate the delay experienced by Poisson arriving packets for HARQ-CC. We provide analytical expressions for the average waiting time, the packets sojourn time, the average consumed power, and the energy efficiency. In our investigation, we take into account the impact of imperfect feedback on different performance metrics. Additionally, we explore the tradeoff between energy efficiency and the throughput. The proposed scheme is shown to maintain the outage probability below a specified threshold which ensures the link reliability. Meanwhile, HARQ-CC adapts implicitly the transmission rate to the channel conditions such that the throughput is maximized. Our results demonstrate that HARQ-CC allows improving the achievable communication rate compared to fixed time diversity schemes. To maximize the throughput of HARQ-CC, the rate per HARQ round should be less than the rate required to meet the outage constraint. Our investigation of the performance of HARQ-CC over Rayleigh and double Rayleigh channels shows that double Rayleigh channels have a higher severity of fading and result in a larger degradation of the throughput. Our analysis reveals that HARQ with incremental redundancy (HARQ-IR) achieves a larger throughput compared to HARQ-CC, while HARQ-CC is simpler to implement, has a lower decoding complexity, and requires less memory resources. Index Terms-Vehicle-to-vehicle communications, double Rayleigh channel, hybrid automatic repeat request (HARQ), code combining, throughput, delay analysis, energy efficiency, information outage capacity.
doi:10.1109/tvt.2018.2794183 fatcat:42fnuyyy2jbmnpbg2vyxjvsfcm

Light based underwater wireless communications

Hassan M. Oubei, Chao Shen, Abla Kammoun, Emna Zedini, Ki-Hong Park, Xiaobin Sun, Guangyu Liu, Chun Hong Kang, Tien Khee Ng, Mohamed-Slim Alouini, Boon S. Ooi
2018 Japanese Journal of Applied Physics  
A more comprehensive study to characterize turbulence-induced fading in UWOC channels in the presence of air bubbles for fresh and salty waters, based on experimental data was proposed by Zedini et al.  ... 
doi:10.7567/jjap.57.08pa06 fatcat:47jzxhs65jgerabpz4szj4oymi

Unified Statistical Channel Model for Turbulence-Induced Fading in Underwater Wireless Optical Communication Systems

Emna Zedini, Hassan Makine Oubei, Abla Kammoun, Mounir Hamdi, Boon S. Ooi, Mohamed-Slim Alouini
2019 IEEE Transactions on Communications  
Zedini high data rates, low-latency, high transmission security, and reduced energy consumption, compared with their acoustic counterparts [1] , [6] , [7] .  ... 
doi:10.1109/tcomm.2019.2891542 fatcat:x6g6i6zicbhwdfgiyg6x3jchye

A New Simple Model for Underwater Wireless Optical Channels in the Presence of Air Bubbles

Emna Zedini, Hassan M. Oubei, Abla Kammoun, Mounir Hamdi, Boon S. Ooi, Mohamed-Slim Alouini
2017 GLOBECOM 2017 - 2017 IEEE Global Communications Conference  
A novel statistical model is proposed to characterize turbulence-induced fading in underwater wireless optical channels in the presence of air bubbles for fresh and salty waters, based on experimental data. In this model, the channel irradiance fluctuations are characterized by the mixture Exponential-Gamma distribution. We use the expectation maximization (EM) algorithm to obtain the maximum likelihood parameter estimation of the new model. Interestingly, the proposed model is shown to provide
more » ... a perfect fit with the measured data under all the channel conditions for both types of water. The major advantage of the new model is that it has a simple mathematical form making it attractive from a performance analysis point of view. Indeed, the application of the Exponential-Gamma model leads to closed-form and analytically tractable expressions for key system performance metrics such as the outage probability and the average bit-error rate.
doi:10.1109/glocom.2017.8254240 dblp:conf/globecom/ZediniOKHOA17 fatcat:rxp2ivslvzadjgez6lzj6khqwm

On the Performance Analysis of Hybrid ARQ With Incremental Redundancy and With Code Combining Over Free-Space Optical Channels With Pointing Errors

Emna Zedini, Ali Chelli, Mohamed-Slim Alouini
2014 IEEE Photonics Journal  
In this paper, we investigate the performance of hybrid automatic repeat request (HARQ) with incremental redundancy (IR) and with code combining (CC) from an information-theoretic perspective over a point-to-point free-space optical (FSO) system. First, we introduce new closed-form expressions for the probability density function, the cumulative distribution function, the moment generating function, and the moments of an FSO link modeled by the Gamma fading channel subject to pointing errors
more » ... using intensity modulation with direct detection technique at the receiver. Based on these formulas, we derive exact results for the average bit error rate and the capacity in terms of Meijer's G functions. Moreover, we present asymptotic expressions by utilizing the Meijer's G function expansion and using the moments method, too, for the ergodic capacity approximations. Then, we provide novel analytical expressions for the outage probability, the average number of transmissions, and the average transmission rate for HARQ with IR, assuming a maximum number of rounds for the HARQ protocol. Besides, we offer asymptotic expressions for these results in terms of simple elementary functions. Additionally, we compare the performance of HARQ with IR and HARQ with CC. Our analysis demonstrates that HARQ with IR outperforms HARQ with CC.
doi:10.1109/jphot.2014.2339331 fatcat:6s66znplvnhh7a6pp7ymkqajbe

Unified performance analysis of mixed line of sight RF-FSO fixed gain dual-hop transmission systems

Emna Zedini, Imran Shafique Ansari, Mohamed-Slim Alouini
2015 2015 IEEE Wireless Communications and Networking Conference (WCNC)  
In this work, we carry out a unified performance analysis of a dual-hop fixed gain relay system over asymmetric links composed of both radio-frequency (RF) and unified freespace optics (FSO) under the effect of pointing errors. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e. heterodyne detection and intensity modulation with direct detection (IM/DD)). In particular, we derive new
more » ... d closed-form expressions for the cumulative distribution function, the probability density function, the moment generation function, and the moments of the end-toend signal-to-noise ratio of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability, the higher-order amount of fading, and the average bit-error rate of a variety of binary modulations in terms of the Meijer's G function. Further, an exact closed-form expression for the end-to-end ergodic capacity for the Nakagami-m-unified FSO relay links is derived in terms of the bivariate G function. All the given results are verified via Computer-based Monte-Carlo simulations. Index Terms-Asymmetric dual-hop relay system, Free-space optical (FSO) communications, mixed radio frequency (RF)/FSO systems, Nakagami-m fading, atmospheric turbulence, pointing errors, outage probability (OP), bit-error rate (BER), amount of fading (AF), ergodic capacity, Meijer's G function.
doi:10.1109/wcnc.2015.7127443 dblp:conf/wcnc/ZediniAA15 fatcat:gajjuzp4fvahbnx7zol737epja
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