Performance Analysis and Software-Defined Implementation of Real-Time MIMO FSO With Adaptive Switching in GNU Radio Platform

In this paper, we provide the first software-based implementation of multiple-input multiple-output (MIMO) free space optical (FSO) link with the adaptive switching based on the software defined radio developed by GNU Radio software system, which emulates the real-time capability of the proposed scheme. We propose a switching mechanism to independently configure each transmitter and receiver, based on the channel state information provided at the transmitter via a feedback link and evaluate the link performance under atmospheric conditions such as fog and turbulence. We also validate the advantages of mitigating both the turbulence and fog in the proposed multiple input multiple output FSO system by means of numerical simulations and the developed GNU Radio software platform. We demonstrate that the proposed system can effectively operate in heavy fog with bit error rates (BER) within the range of 10
⁻⁸
to
$\sim 10^{-7}$
over link spans of 100, 200 and 300 m. Additionally the system has been shown to mitigate moderate turbulence over a 100 m link span with BER of
$\sim 10^{-7}$
.