Multiuser Scheduling for Asymmetric FSO/RF Links in Satellite-UAV-Terrestrial Networks

• Published in: IEEE wireless communications letters Vol. 9; no. 8; pp. 1235 - 1239
• Main Authors: Kong, Huaicong, Lin, Min, Zhu, Wei-Ping, Amindavar, Hamidreza, Alouini, Mohamed-Slim
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.08.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: asymmetric FSO/RF link; Asymmetry; Beamforming; ergodic capacity; Fading channels; multiuser scheduling; Optical fiber communication; Protocols; Radio frequency; Satellite communication; Satellites; Scheduling; Signal to noise ratio; Unmanned aerial vehicles
• ISSN: 2162-2337; 2162-2345
• DOI: 10.1109/LWC.2020.2986750

This letter investigates the multiuser downlink transmission performance of an asymmetric free space optical (FSO)/radio frequency (RF) link. Here, the satellite delivers signal to the unmanned aerial vehicle (UAV) through a FSO link subject to Gamma-Gamma distributed turbulence, while the UAV forwards the decoded signal to multiple users through RF links characterzied by the correlated Rayleigh fading channel. By adopting that the selective decode-and-forward (DF) protocol at the UAV, we derive a closed-form expression for ergodic capacity (EC) of the considered system, where the RF link exploits transmit beamforming (BF) based on statistical channel state information (CSI) to obtain better performance than single antenna scenarios in existing works. Then, with the help of the derived EC and the available statistical CSI, a novel proportional fair scheduling (PFS) scheme is proposed. Finally, numerical results are conducted to verify the correctness of the theoretical analysis and the superiority of the proposed scheduling scheme.