Satellite and unmanned aerial vehicles (UAV) integrated networks (SUINs) are considered as a promising method to offer various internet of remote things (IoRT) applications. In this paper, we investigate the downlink transmission of SUINs where the satellite to UAV link uses free-space optical (FSO) technology with equal gain combining (EGC) scheme while the links from UAV to IoRT devices exploit radio frequency (RF) with space division multiple access (SDMA) technique. Specifically, considering that only statistical channel state information (CSI) is available, we first formulate an optimization problem to maximize the ergodic sum rate (ESR) of the system, which is constrained by total transmit power budget and IoRT devices’ rate requirements. Then, a beamforming (BF) scheme based on alternating direction method of multipliers (ADMM) is proposed to solve the non-convex problem. Furthermore, a zero-forcing (ZF) based suboptimal approach is also presented to reduce the implementation complexity. Finally, by assuming that the FSO link and RF links are subject to Gamma-Gamma fading and Nakagami-m fading, respectively, we derive closed-form ESR expressions for the considered network with the proposed BF schemes. Simulation results are provided to confirm the accuracy of theoretical analysis. Moreover, it is revealed that our proposed EGC scheme for FSO communication and BF schemes for RF transmission can both achieve better performance than the existing works.
ASJC Scopus subject areas
- Signal Processing
- Information Systems
- Information Systems and Management
- Computer Science Applications
- Hardware and Architecture
- Computer Networks and Communications