Performance Analysis of Free-Space Optical Links Over Málaga ($\mathcal{M} $) Turbulence Channels With Pointing Errors

Abstract

In this work, we present a unified performance analysis of a free-space optical (FSO) link that accounts for pointing errors and both types of detection techniques (i.e. intensity modulation/direct detection (IM/DD) as well as heterodyne detection). More specifically, we present unified exact closedform expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system, all in terms of the Meijer's G function except for the moments that is in terms of simple elementary functions. We then capitalize on these unified results to offer unified exact closed-form expressions for various performance metrics of FSO link transmission systems, such as, the outage probability, the scintillation index (SI), the average error rate for binary and M -ary modulation schemes, and the ergodic capacity (except for IM/DD technique, where we present closed-form lower bound results), all in terms of Meijer's G functions except for the SI that is in terms of simple elementary functions. Additionally, we derive the asymptotic results for all the expressions derived earlier in terms of Meijer's G function in the high SNR regime in terms of simple elementary functions via an asymptotic expansion of the Meijer's G function. We also derive new asymptotic expressions for the ergodic capacity in the low as well as high SNR regimes in terms of simple elementary functions via utilizing moments. All the presented results are verified via computer-based Monte-Carlo simulations.Index Terms-Free-space optical (FSO) communications, optical wireless communications, pointing errors, Lognormal turbulence channels, Gamma-Gamma turbulence channels, Málaga (M) turbulence channels, outage probability (OP), binary modulation schemes, bit-error rate (BER), symbol error rate (SER), scintillation index (SI), ergodic capacity, Meijer's G function.are cost-effective relative to the traditional RF links. It is a promising technology as it offers full-duplex Gigabit Ethernet throughput in certain applications and environment offering a huge license-free spectrum, immunity to interference, and high security [1]. These features of FSO communication systems potentially enable solving the issues that the RF communication systems face due to the expensive and scarce spectrum [1]-[10]. Additionally, FSO communications does offer bandwidth as the world record stands at 1.2 Tbps or 1200 Gbps [11]. Besides these nice characteristic features of FSO communication systems, they span over long distances of 1Km or longer. However, the atmospheric turbulence may lead to a significant degradation in the performance of the FSO communication systems [1].Thermal expansion, dynamic wind loads, and weak earthquakes result in the building sway phenomenon that causes vibration of the transmitter beam leading to a misalignment between transmitter and receiver known as pointing error. These pointing errors may lead to significant perfo...

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A Novel Mirror-Aided Non-Imaging Receiver for Indoor $2\times 2$ MIMO-Visible Light Communication Systems

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“…Finally, we also should remark that for the sake of clarity, we have not either considered misalignment effects between the transmitter and the receiver. However, these effects could be included by using the M distribution with pointing errors reported in [23,24].…”