Optical adaptive power transmission using APC-EDFA for turbulence-tolerant FSO communications

This paper proposes a novel optical adaptive power transmission using automatic power control (APC)-erbium-doped fiber amplifier (EDFA) for turbulence-tolerant free-space optical (FSO) communications. Based on the quasi-stationary characteristics of turbulence channel and average power dependent optical gain features of EDFA, the channel state information (CSI) of the received upstream on-off keying (OOK) signal is optically conveyed to the orthogonally polarized transmitted downstream OOK signal with channel inversion via EDFA in APC mode. The performance is analyzed under various dynamic gain frequencies of APC-EDFA and different power ratios between downstream and upstream signals. Simulation results revealed that the power of downstream signal was adaptively transmitted according to the received upstream signal under effective turbulence suppression, transmitted power efficiency, and required SNR reduction without the estimation of CSI.