Experimental and analytical investigations of a MIMO-based FSO-fiber communication network under the combined effects of fog and turbulence

This paper presents the analytical and experimental emulation of a multiple input multiple outputs (MIMO) free-space optical-fiber converged (FSO-FC) communication network under three free-space channel scenarios: i) only turbulence, ii) only fog, and iii) combined effects of fog and turbulence generated in a laboratory. We derive a novel expression of the probability density function (PDF) for the FSO channel gain under the combined effects of fog and turbulence, which fits well with experimental results. The average bit error rate (ABER) is evaluated through experiments and closely matches our analytical findings. We further obtain closed-form expressions for outage probability (OP) and average channel capacity (ACC) under the combined effects of fog and turbulence. Furthermore, our experiments demonstrate that the 2 × 2 MIMO system with cyclic redundancy check (CRC) bits offers significant performance improvements over the single input, single output (SISO) FSO-FC system. Key parameters like turbulence, fog density, and fiber length are analyzed for system performance insights.