OAM Mode Selection and Space-Time Coding for Atmospheric Turbulence Mitigation in FSO Communication

• Published in: IEEE access Vol. 7; pp. 88049 - 88057
• Main Authors: Amhoud, El Mehdi, Trichili, Abderrahmen, Ooi, Boon S., Alouini, Mohamed-Slim
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Angular momentum; Atmospheric turbulence; Coding; Communications systems; Crosstalk; Encoding; Free-space optical communication; Intermodal; MIMO (control systems); MIMO communication; Modal choice; mode selection; Multiplexing; Optical transmitters; Orbital angular momentum (OAM); Orbits; Orthogonal Frequency Division Multiplexing; Propagation modes; Space vehicles; space-time coding
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2019.2925680

Orbital angular momentum (OAM) multiplexing has recently received considerable interest in free space optical (FSO) communications. Propagating OAM modes through free space may be subject to atmospheric turbulence (AT) distortions that cause intermodal crosstalk and power disparities between OAM modes. In this paper, we are interested in multiple-input-multiple-output (MIMO) coherent FSO communication systems using the OAM. We propose a selection criterion for the OAM modes to minimize the impact of the AT. To further improve the obtained performance, we propose a space-time (ST) coding scheme at the transmitter. Through numerical simulations of the error probability, we show that the penalty from AT is completely absorbed for the weak AT regime, and considerable coding gains are obtained in the strong AT regime.