Enhanced WDM-based dual polarisation free-space optics with intelligent DSP compensation

Abstract

This paper presents a comprehensive analysis of an enhanced dual-polarisation free-space optics (DP-FSO) communication system incorporating wavelength division multiplexing (WDM) and intelligent digital signal processing (DSP) techniques. The proposed system achieves data rates exceeding 400 Gbps over 10 km transmission distances using higher-order modulation schemes including 16-QAM, 32-QAM, 64-QAM, and 128-QAM across multiple wavelength channels. Advanced DSP algorithms including adaptive equalisation, frequency offset correction, I/Q imbalance compensation, and common phase error (CPE) correction are implemented to mitigate atmospheric turbulence effects and system impairments. Performance evaluation demonstrates that the WDM-enhanced DP-FSO system maintains bit error rates below 10⁻³ under moderate atmospheric turbulence conditions while supporting spectral efficiencies up to 16 bits/s/Hz. The system shows robustness against polarisation-dependent losses up to 3 dB and crosstalk levels down to −20 dB. Results indicate that the proposed system offers a viable solution for high-capacity terrestrial and satellite communication links requiring reliable performance under diverse atmospheric conditions.