Free Space Optics (FSO) communication technology with Multi-input and Multi-output (MIMO) and subcarrier intensity modulation (SIM) has captivated interests in research due the diversity gain offered by MIMO. Atmospheric turbulence and pointing errors are the major challenges that affect the FSO system performance. In this work, the FSO based 2×1 Alamouti scheme employing SIM and Q-PSK is analyzed and compared without using Alamouti scheme with Gamma-Gamma (GG) fading channel considering pointing error effects. We derived the closed form expressions for symbol error rate (SER) with Alamouti scheme under the effect of different atmospheric turbulence and pointing errors using moment generating function (MGF). As a result, the proposed system could achieve a high signal-to-noise ratio(SNR) gain of 27 dB over the without Alamouti scheme under moderate and strong turbulence regime. © 2017 IEEE.

Aarthi G

Department of Communication Engineering

School of Electronics Engineering

Vellore Campus

Ramachandra Reddy G

Prabu Krishnasamy

School of Mechanical Engineering

Chennai Campus

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

2017 Innovations in Power and Advanced Computing Technologies (i-PACT)

The average spectral efficiency (ASE) is investigated for the free space optical (FSO) communications employing On-Off keying (OOK), Polarization shift keying (POLSK), and Coherent optical wireless communication (Coherent OWC) systems with and without pointing errors over the Gamma-Gamma (GG) channels. Additionally, the impact of aperture averaging on the ASE is explored. The influence of different turbulence conditions along with varying receiver aperture has been studied and analyzed. For the considered system, the exact average channel capacity (ACC) expressions are derived using Meijer G function. Results reveal that when pointing errors are introduced, there is a significant reduction in the ASE performance. The enhancement in the ASE can be achieved with an increase in the receiver aperture across various turbulence regimes and reducing the beam radius in the presence of pointing errors, but the rate of increment of ASE reduces with a larger diameter and it is saturated finally. The coherent OWC system provides better ASE performance of 49 bits/s/Hz at the average transmitted optical power of 5 dBm with an aperture diameter of 10 cm and 34 bits/s/Hz without and with pointing errors under strong turbulence respectively. © 2016 Elsevier B.V.

Optics Communications

Aperture averaging effects on the average spectral efficiency of FSO links over turbulence channel with pointing errors

On the performances of relay-aided FSO system over M distribution with pointing errors in presence of various weather conditions

Analysis of link performance and robustness of homodyne BPSK for airborne backbone laser communication system

IEEE Wireless Communications Letters

On the Performance of Alamouti Scheme in Gamma-Gamma Fading FSO Links With Pointing Errors

Table of Integrals, Series, and Products

NORMS

Performance analysis of alamouti scheme in turbulence induced fading with pointing errors

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