Abstract

The bit error rate (BER) performance of the free space optical (FSO) link suffers from the atmospheric turbulence. By employing additional transmit and receive apertures at the transmitter and receiver, respectively, the error rate of the FSO communication system can be significantly improved. However, the pointing errors (PEs), generated because of the building sway, have the potential to eradicate the benefits of the multiple transmit and/or receive apertures-based FSO communication system. Therefore, for a general and realistic study of the FSO multiple-input multiple-output (MIMO) system, the effect of PEs in the Gamma–Gamma (GG) fading atmospheric fluctuations is considered in this paper. We study two schemes for the FSO MIMO systems: 1) equal gain combining (EGC), and 2) maximal ratio combining (MRC). A new power series-based representation is proposed for the probability density function of the GG fading FSO links with PEs. This new series representation contains only the terms with exponent of the random variable (RV) as compared to the closed-form representation, which contains the Meijer-G function of the RV. Then, we derive the average BER for both combining schemes over the GG fading FSO links with PEs. By using the derived BER expressions, we derive the asymptotic BER for both schemes. The analytical diversity order and combining gains for both systems are also obtained. The effect of PEs over the performance of the schemes is analyzed under different scenarios and it is observed that the PEs significantly degrade the diversity of the FSO MIMO system. It is deduced by simulation and analysis that though the EGC scheme is simpler to implement in practice but the MRC scheme is more rugged to the large PEs.

© 2016 IEEE

On the Performance of Multiplexing FSO MIMO Links in Log-Normal Fading With Pointing Errors

Mohammad Taghi Dabiri, Mohammad Javad Saber, and Seyed Mohammad Sajad Sadough
J. Opt. Commun. Netw. 9(11) 974-983 (2017)

Asymptotic error-rate analysis of FSO links using transmit laser selection over gamma-gamma atmospheric turbulence channels with pointing errors

Antonio García-Zambrana, Beatriz Castillo-Vázquez, and Carmen Castillo-Vázquez
Opt. Express 20(3) 2096-2109 (2012)

Imperfect-Quantized-Feedback-Based Beamforming for an FSO MISO System Over Gamma–Gamma Fading With Pointing Errors

Ankit Garg, Manav R. Bhatnagar, Olivier Berder, and Baptiste Vrigneau
J. Opt. Commun. Netw. 9(11) 1005-1018 (2017)

M-ary phase-shift keying-based single-input-multiple-output free space optical communication system with pointing errors over a gamma–gamma fading channel

Suman Malik and Prasant Kumar Sahu
Appl. Opt. 59(1) 59-67 (2020)

Bit detect and forward relaying for FSO links using equal gain combining over gamma-gamma atmospheric turbulence channels with pointing errors

Antonio García-Zambrana, Carmen Castillo-Vázquez, Beatriz Castillo-Vázquez, and Rubén Boluda-Ruiz
Opt. Express 20(15) 16394-16409 (2012)