Outage performance of MIMO FSO links over strong turbulence and misalignment fading channels

Antonio García-Zambrana, Carmen Castillo-Vázquez, Beatriz del Castillo-Vázquez
January 2011
Cite DOI URL

Abstract

Atmospheric turbulence produces fluctuations in the irradiance of the transmitted optical beam, which is known as atmospheric scintillation, severely degrading the performance over free-space optical (FSO) links. Additionally, since FSO systems are usually installed on high buildings, building sway causes vibrations in the transmitted beam, leading to an unsuitable alignment between transmitter and receiver and, hence, a greater deterioration in performance. In this paper, the outage probability as a performance measure for multiple-input/multiple-output (MIMO) FSO communication systems with intensity modulation and direct detection (IM/DD) over strong atmospheric turbulence channels with pointing errors is analyzed. Novel closed-form expressions for the outage probability as well as their corresponding asymptotic expressions are presented when the irradiance of the transmitted optical beam is susceptible to either strong turbulence conditions, following a negative exponential distribution, and pointing error effects, following a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. Obtained results show that the diversity order is independent of the pointing error when the equivalent beam radius at the receiver is at least twice the value of the pointing error displacement standard deviation at the receiver. Simulation results are further demonstrated to confirm the analytical results. Additionally, since proper FSO transmission requires transmitters with accurate control of their beamwidth, asymptotic expressions here obtained for different diversity techniques are used to find the optimum beamwidth that minimizes the outage performance. © 2011 Optical Society of America.

Type
Journal article
Publication
Optics Express
Atmosphere Computer Simulation Models Theoretical Optical Devices Telecommunications Alignment Atmospheric Turbulence Communication Systems Fading Channels Jitter Optical Communication Probability Distributions Transmitters Analytical Results Asymptotic Expressions Atmospheric Scintillation Atmospheric Turbulence Channels Beam Widths Closed-Form Expression Detector Size Diversity Order Diversity Techniques Equivalent Beams Fading Models Free-Space Optical High Building Intensity Modulation and Direct Detections Jitter Variance Multiple Input/Multiple Outputs Negative Exponential Distribution Optical Beams Outage Performance Outage Probability Performance Measure Pointing Errors Simulation Result Standard Deviation Strong Turbulence Transmitted Beams Transmitter and Receiver Article Chemistry Instrumentation Optical Instrumentation Telecommunication Theoretical Model Atmospheric Thermodynamics
Antonio García-Zambrana
Antonio García-Zambrana
Professor of Telecommunications Engineering

Professor at the University of Málaga working on wireless optical communications, free-space optical links, underwater optical wireless communications, visible light communications, and FPGA/RFSoC-based real-time prototyping.

Beatriz del Castillo-Vázquez
Beatriz del Castillo-Vázquez
Associate Professor of Telecommunications Engineering

Associate Professor at the University of Málaga working on wireless optical communications, free-space optical links, underwater optical wireless communications, optical channel modelling and system-level performance analysis.