Performance of UAV-Assisted Multiuser Terrestrial-Satellite Communication System Over Mixed FSO/RF Channels

In this letter, performance of a multiantenna multiuser unmanned aerial vehicle (UAV)-assisted terrestrial-satellite communication system over mixed free space optics (FSO)/radiofrequency (RF) channels is analyzed. Downlink transmission from the satellite to UAV completed through FSO link which follows gamma–gamma distribution with pointing error impairments. Both heterodyne detection and intensity modulation direct techniques are considered at receiver. To avail antenna diversity, multiple transmit antennas UAV. Selective decode-and-forward scheme assumed opportunistic user scheduling performed while considering practical constraints outdated channel state information (CSI) during selection phase. The RF links follow Nakagami-m due its versatile nature. context, for analysis, analytical expressions outage probability, asymptotic ergodic capacity, effective generalized average symbol-error-rate various quadrature amplitude (QAM) schemes such as hexagonal-QAM, cross-QAM, rectangular QAM derived. A comparison presented. Further, impact error, number antennas, delay constraint, fading severity, imperfect CSI highlighted on performance. Finally, all results verified Monte–Carlo simulations.