Mitigation of turbulence induced scintillation using concave mirror in reflection-assisted OOK free space optical links

This paper introduces an effective technique of ameliorating free-space optical (FSO) communication whenever the line-of-sight (LOS) between the end-to-end link nodes is obstructed. Additionally, we also present a novel statistical technique of estimating FSO channel state information (CSI) for analysing the link performance in terms of system BER and short duration deep fades whenever a laser signal traverses a turbulent FSO channel. The consistency of the proposed CSI estimation method is experimentally evaluated over a test-bed FSO link in a laboratory controlled weak turbulence conditions. The numerical results reveal that the CSI-assisted receiver sensitivity at BER =10−9 under weak turbulence is improved by 16.36 % as against the fixed threshold based detector. Based on the experimental outcomes, the scintillation rate is observed to be reduced by 45.26 %, while the statistical results indicate that the requisite power penalty to achieve outage of 10−9 in weak turbulence is reduced by 2.2 dB when a concave reflector is incorporated instead of plane optical reflector for bridging the FSO communication in an obstructed LOS link.