TY - JOUR
T1 - Unified Performance Analysis of Multi-Hop FSO Systems over Double Generalized Gamma Turbulence Channels with Pointing Errors
AU - Ashrafzadeh, Behnam
AU - Zaimbashi, Amir
AU - Soleimani-Nasab, Ehsan
AU - Uysal, Murat
N1 - Funding Information:
Manuscript received November 24, 2019; revised May 31, 2020; accepted July 25, 2020. Date of publication August 18, 2020; date of current version November 11, 2020. The work of Behnam Ashrafzadeh, Amir Zaimbashi, and Ehsan Soleimani-Nasab was supported in part by the Iran National Science Foundation (INSF) under Grant 98002726. This article was presented in part at the 2018 IEEE Global Communications Conference (GLOBECOM), Abudhabi, United Arab Emirates, December 2018. The associate editor coordinating the review of this article and approving it for publication was I. Guvenc. (Corresponding author: Amir Zaimbashi.) Behnam Ashrafzadeh and Amir Zaimbashi are with the Optical and RF Communication Systems Laboratory, Department of Electrical Engineering, Shahid Bahonar University of Kerman, Kerman 7616914111, Iran (e-mail: ashrafzadeh@eng.uk.ac.ir; a.zaimbashi@uk.ac.ir).
Publisher Copyright:
© 2002-2012 IEEE.
PY - 2020/11
Y1 - 2020/11
N2 - Free space optical (FSO) communication systems provide high bandwidth in unregulated spectrum and act as a powerful line-of-sight wireless connectivity solution. The performance of FSO systems can be seriously impaired by fading as a result of atmospheric turbulence and/or pointing errors due to misalignment. In the context of FSO systems, relaying was proposed as an effective fading mitigation technique due to the fact that the variance is distance-dependent in turbulence channels. In this article, we present a unified performance analysis of multi-hop FSO systems over Double Generalized Gamma (DGG) turbulence channels with pointing error impairments. We assume amplify-and-forward relaying and consider both heterodyne detection and intensity modulation with direct detection. We derive tight closed-form expressions for the outage probability and bit error probability of both fixed-gain and channel state information (CSI)-assisted relaying in terms of the bivariate Fox-H functions and Fox-H functions, respectively. We further analyze asymptotic behavior of the outage probability in terms of simple elementary functions and obtain the achievable diversity orders. Diversity gain is found to be a function of atmospheric turbulence parameters, pointing error, detection type and the number of hops. Monte Carlo simulation results are further provided to verify the accuracy of the derived expressions.
AB - Free space optical (FSO) communication systems provide high bandwidth in unregulated spectrum and act as a powerful line-of-sight wireless connectivity solution. The performance of FSO systems can be seriously impaired by fading as a result of atmospheric turbulence and/or pointing errors due to misalignment. In the context of FSO systems, relaying was proposed as an effective fading mitigation technique due to the fact that the variance is distance-dependent in turbulence channels. In this article, we present a unified performance analysis of multi-hop FSO systems over Double Generalized Gamma (DGG) turbulence channels with pointing error impairments. We assume amplify-and-forward relaying and consider both heterodyne detection and intensity modulation with direct detection. We derive tight closed-form expressions for the outage probability and bit error probability of both fixed-gain and channel state information (CSI)-assisted relaying in terms of the bivariate Fox-H functions and Fox-H functions, respectively. We further analyze asymptotic behavior of the outage probability in terms of simple elementary functions and obtain the achievable diversity orders. Diversity gain is found to be a function of atmospheric turbulence parameters, pointing error, detection type and the number of hops. Monte Carlo simulation results are further provided to verify the accuracy of the derived expressions.
KW - Free space optical communications
KW - diversity order
KW - double generalized gamma
KW - multi-hop relaying
KW - outage probability
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U2 - 10.1109/TWC.2020.3015780
DO - 10.1109/TWC.2020.3015780
M3 - Article
AN - SCOPUS:85096413865
SN - 1536-1276
VL - 19
SP - 7732
EP - 7746
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
IS - 11
M1 - 9170804
ER -