Link budget profile for non-line-of-sight atmospheric infrared links

This paper investigates the various sources of power loss encountered in non-line-of-sight (NLOS) terrestrial free space optical (FSO) communication system. To analyze the effect of losses, we propose a numerical model for characterizing the losses emerging over the key NLOS FSO link nodes. Additionally, we present an experimental test-bed for estimating the level of signal phase shift and distortions induced in NLOS FSO communication. The harmonic distortion analysis envisages that the non-linearity imposed by the laser module and optical reflector is negligible and hence, is not obligatory for gauging power loss in the link budget equation. It is also perceived that the optical reflector induces a minimal phase shift in the received optical beams. Finally, the link budget is incorporated for analyzing the theoretical power limited link range of an NLOS FSO system. Based on the analytical study, it is apparent that the proposed channel state information (CSI) estimator assisted IR system model can reliably bridge the FSO communication between the end users even when the direct line-of-sight is unavailable.