Robust Precoding for Cooperative Massive MIMO LEO Satellite-Terrestrial Networks

Low earth orbit (LEO) satellites, with advantages such as wide coverage and resilience to obstacles, make the establishment of a cooperative satellite-terrestrial network (STN) a feasible solution to address the limitations of terrestrial networks. In the cooperative STN, employing massive multiple-input multiple-output (MIMO) technology can fulfill the requirements for wide coverage and high-quality service. However, due to angle estimation errors in LEO satellite communication, acquiring channel state information (CSI) poses significant challenges. To tackle this issue, this paper explores robust precoding in the cooperative massive MIMO LEO STN. Specifically, we first introduce the imperfect CSI model. Then, we formulate the problem of maximizing the sum rate and propose a robust precoding scheme that designs the precoders for both base stations (BSs) and the LEO satellite, leveraging imperfect CSI and error distribution information. Simulation results demonstrate the validity of our robust precoding scheme.