Performance analysis of a differential chaos-based hybrid FSO/RF satellite–terrestrial uplink

This paper proposes a hybrid free-space optics (FSO)/radio frequency (RF) satellite-terrestrial communication system assisted by high-altitude platform (HAP), incorporating differential chaos shift keying (DCSK) modulation and Bose-Chaudhuri-Hocquenghem (BCH) coding techniques. By utilizing parallel FSO and RF transmission in the terrestrial-HAP link and performing maximal ratio combining (MRC) at the HAP node, the system effectively mitigates the effects of atmospheric turbulence and adverse weather conditions, such as haze and fog. For the FSO satellite-terrestrial uplink, factors including angle of arrival (AoA) fluctuations, pointing errors, atmospheric attenuation, intensity scintillation, and beam wander are considered. The Fischer-Snedecor F distribution and Nakagami-m distribution are used to model the FSO and RF links, respectively, and the bit error rate (BER) expression for the BCH-coded DCSK modulation system is derived. Through simulations, the impact of modulation and coding parameters, such as zenith angle, beam divergence angle, field of view angle, various modulation techniques, and weather conditions, on system performance is analyzed. The performance of the proposed system is also compared with that of the traditional satellite-terrestrial laser communication system and the selection combining (SC) scheme in the terrestrial-HAP link. Finally, the analytical results were validated through Monte Carlo simulations. Results indicate that the hybrid FSO/RF satellite-terrestrial communication system with BCH-DCSK technology exhibits superior performance, providing theoretical support for future experiments on satellite-terrestrial uplink communication.