Simulative verification of channel reciprocity in free-space optical inter-HAP links

Channel reciprocity in a bidirectional turbulent channel implies that the received powers are correlated to a certain extent at both link ends. In this paper, we investigate by numerical phase-screen propagation simulation the variation of the channel correlation under various boundary conditions, namely orthogonal wind speed, link distance, receiver aperture and turbulence-strength profile for inter High Altitude Platform (HAP) FSO links. Finally, we provide an outlook to different Error Control Coding (ECC) methods that make use of the reciprocity effect.