Performance Analysis of Hybrid RF/FSO-Based SAGIN with Co-Channel Interference

Abstract

The rapid development of sixth-generation (6G) wireless systems has accelerated the integration of terrestrial and non-terrestrial networks (NTNs) to achieve ubiquitous, high capacity communication. In this study, we investigate the outage performance of a dual-hop space-air-ground integrated network (SAGIN) in which an unmanned aerial vehicle (UAV) operates as an aerial decode-and-forward relay between a ground user and a satellite destination in the presence of multiple co-channel inter-ference (CCI). The proposed framework adopts a hybrid radio frequency/free-space optical (RF/FSO) transmission architecture to enhance reliability in challenging propagation environments. The first hop experiences Nakagami-m fading for both the desired and multiple CCI signals, whereas the second hop employs hybrid RF/FSO links with selection combining at the destination. The FSO link accounts for Gamma-Gamma (GG) atmospheric turbu-lence and pointing errors, whereas the RF backup link follows a shadowed Rician fading model. The numerical results show that increasing the number of interferers degrades reliability, whereas higher Nakagami-m parameters and improved pointing accuracy significantly enhance performance. The proposed SAGIN with a hybrid RF/FSO framework provides improved robustness under severe fading and atmospheric conditions, making it a promising solution for NTN-enabled 6G communications.