Experimental Validation of ACO-OTFS Signal Transmission Over Turbulent FSO Channels

This paper investigates the performance of asymmetrically clipped optical orthogonal time frequency space (ACOOTFS) modulation combined with a residual dense network (RDN) signal detection scheme in free-space optical (FSO) communication systems under atmospheric turbulence conditions. We propose an experimental framework featuring an atmospheric turbulence chamber capable of simulating weak-tomoderate turbulence conditions, while simultaneously enabling performance evaluation of the ACO-OTFS system under realistic turbulence scenarios. Comparative analysis demonstrates that the proposed RDN detector achieves superior bit error rate (BER) performance compared to conventional maximum likelihood detection, particularly without channel state information scenarios, with the performance advantage becoming more pronounced as the modulation order increases. Notably, the RDN model through offline training maintains robust detection capability when deployed in realistic turbulence conditions, demonstrating effective simulation-to-reality transfer. These findings validating the atmospheric turbulence chamber as an effective testbed for turbulent FSO communication system development.