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

Abstract

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 MIMO FSO system by means of numerical simulations and the developed GNU Radio software platform.

Experimental real-time GbE MIMO FSO under fog conditions with software defined GNU Radio platform-based adaptive switching

“…Finally, we also considered longer link lengths of 500 m, 1 km, and 2 km with the same atmospheric losses for practical applications and theoretically enumerated that V of 1, 2, and 4 km are the points of switching, respectively. Furthermore, we have obtained a similar improvement in system performance under fog conditions compared to previous work in [9,36].…”

“…To address the weather impact on the FSO link performance and ensure link availability at all times, techniques such as hybrid RF/FSO, multiple input multiple output (MIMO) FSO with spatial diversity (SD), and relayed FSO systems have been proposed in the literature [2]. Amongst the proposed solutions, SD techniques has been proven to perform better compared to the single FSO link in terms of bit error rate (BER) performance to mitigate the degradation due to the fog condition [9].…”

“…A comparative study of single input single output (SISO) and MIMO FSO systems under different weather conditions has been reported in the literature, showing that MIMO outperforms SISO in terms of the received power level and BER in [9][10][11]. Aside from MIMO and SD techniques, adaptive modulation and low-density parity-check coding for the SISO FSO system were proposed in [12], showing tolerance to a deep fade of the order of 30 dB and above under strong turbulence.…”

“…A novel adaptive transmission algorithm for the optimization of both power usage and spectral efficiency for the satelliteto-ground communications with 10 dB of power-saving was proposed in [13]. In [9], a comparative analysis of a MIMO FSO link with adaptive switching to ensure link availability and SISO FSO under fog and turbulence conditions together with the investigation of the optimal threshold in terms of BER in a GNU Radio platform was reported. An analysis of an adaptive modulation FSO system with multiple apertures using the signal-to-noise ratio (SNR) threshold for dynamic adaptation of the modulation scheme was also reported in [14].…”

“…Alternatively, GNU Radio, which is a free and open-source software development toolkit, supports the real-time emulation to control and deploy the hardware using the time domain graphical user interface (GUI) [28]. We have reported the performance analysis of SDR-based MIMO and SISO FSO systems under different fog and turbulence conditions with adaptive switching in GNU Radio in [9]. However, the previous work is a real-time emulation system with a simulated FSO channel.…”