Cooperative Beamforming for Hybrid Satellite-Terrestrial Relay Networks

Abstract

This paper addresses the cooperative beamforming (BF) problem for hybrid satellite-terrestrial relay networks (HSTRNs), where a geostationary satellite transmits signals to a terrestrial mobile terminal (MT) with the help of multiple single-antenna relays. Specifically, we first formulate a constrained optimization problem to maximize the achievable rate of MT while satisfying the total power constraint of relays and the interference-to-noise ratio (INR) constraint at the earth stations (ESs). Then, based on Rayleigh-Ritz method, we propose an iterative BF algorithm to obtain the optimal analytical expressions of weight vector. Furthermore, to reduce computational complexity and transmission delay, we design MRT-based BF scheme as the suboptimal scheme. Finally, numerical results are given to confirm the validity and superiority of the proposed cooperative BF schemes.