Performance Analysis of MIMO Free-Space Optical Systems in Gamma-Gamma Fading

Dept. of Electr. & Comput. Eng., Univ. of British Columbia, Vancouver, BC, Canada
IEEE Transactions on Communications (Impact Factor: 1.99). 11/2009; 57(11):3415-3424. DOI: 10.1109/TCOMM.2009.11.080168
Source: DBLP


Atmospheric turbulence induced fading is one of the main impairments affecting free-space optics (FSO) communications. In recent years, Gamma-Gamma fading has become the dominant fading model for FSO links because of its excellent agreement with measurement data for a wide range of turbulence conditions. However, in contrast to RF communications, the analysis techniques for FSO are not well developed and prior work has mostly resorted to simulations and numerical integration for performance evaluation in Gamma-Gamma fading. In this paper, we express the pairwise error probabilities of single-input single-output (SISO) and multiple-input multiple-output (MIMO) FSO systems with intensity modulation and direct detection (IM/DD) as generalized infinite power series with respect to the signal-to-noise ratio. For numerical evaluation these power series are truncated to a finite number of terms and an upper bound for the associated approximation error is provided. The resulting finite power series enables fast and accurate numerical evaluation of the bit error rate of IM/DD FSO with on-off keying and pulse position modulation in SISO and MIMO Gamma-Gamma fading channels. Furthermore, we extend the well-known RF concepts of diversity and combining gain to FSO and Gamma-Gamma fading. In particular, we provide simple closed-form expressions for the diversity gain and the combining gain of MIMO FSO with repetition coding across lasers at the transmitter and equal gain combining or maximal ratio combining at the receiver.

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    • "It is difficult to determine the probability density function (pdf) for the intensity fluctuations under arbitrary atmospheric conditions and beam parameters. However, based on scintillation statistics, various mathematical models have been proposed such as log-normal [10], Gamma [11] or Gamma-Gamma [12] distribution. In this paper, as we consider weak turbulence scenario, the log-normal distribution model is adopted. "

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    • "Again, a proper truncation should be used so that the approximation error is negligible when the upper limit is large enough. It was found that with the value of 40 for both κ and ι, the truncation error is less than 10 −9 [16], [23]. "
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    ABSTRACT: In this paper, we newly propose and theoreti-cally analyze the performance of all-optical amplify-and-forward (OAF) relaying free-space optical (FSO) systems using erbium-doped fiber amplifier (EDFA) combined with optical hard-limiter (OHL) over atmospheric turbulence channels. The use of OHL enables OAF relaying FSO systems to remove accumulated background noise, which is one of the main factors that limit the system performance. The performance of proposed systems is analytically studied by which closed-form expression for bit-error rate (BER) is formulated, taking into account the effects of at-mospheric turbulence channels and noises caused by background radiation and receiver. The numerical results, which are validated by Monte-Carlo (M-C) simulations, confirm the superiority of the proposed systems in comparison with conventional ones.
    The 2015 IEEE International Conference on Communications (ICC'15), London, United Kingdom; 06/2015
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    • "Moreover, the first hop (RF link) experiences a κ-μ or η-μ fading, and the second hop (FSO link) follows a ΓΓ fading. to the related literature [17]–[19], we consider the high-energy FSO system with the commonly used on-off keying modulation. "
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    ABSTRACT: The mixed radio frequency (RF)/free-space optical (FSO) relaying is a promising technology for coverage improvement, while there lacks unified expressions to describe its performance. In this paper, a unified performance analysis framework of a dual-hop relay system over asymmetric RF/FSO links is presented. More specifically, we consider the RF link follows generalized $kappa$- $mu$ or $eta$-$mu$ distributions, while the FSO link experiences the gamma-gamma distribution, respectively. Novel analytical expressions of the probability density function and cumulative distribution function are derived. We then capitalize on these results to provide new exact analytical expressions of the outage probability and bit error rate (BER). Furthermore, the outage probability for high signal-to-noise ratios and the BER for different modulation schemes are deduced to provide useful insights into the impact of system and channel parameters of the overall system performance. These accurate expressions are general, since they correspond to generalized fading in the RF link and account for pointing errors, atmospheric turbulence, and different modulation schemes in the FSO link. The links between derived results and previous results are presented. Finally, numerical and Monte–Carlo simulation results are provided to demonstrate the validity of the proposed unified expressions.
    Journal of Lightwave Technology 06/2015; 33(11):2286-2293. DOI:10.1109/JLT.2015.2409570 · 2.97 Impact Factor
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