Robust Beamforming for IRS-Enhanced Uplink NOMA Transmission in Satellite Systems

In this article, a robust beamforming (BF) scheme is proposed for an intelligent reflecting surface (IRS)-enhanced uplink non-orthogonal multiple access (NOMA) transmission in satellite communications. Specifically, by assuming that the phase errors of the user-IRS link and user-satellite link follow the Gaussian or uniform distribution, we first formulate a constrained optimization problem to minimize the total transmit power, while satisfying the quality-of-service requirement of each user with the outage probability constraint. Then, a robust BF algorithm based on the central-limit theorem (CLT) and alternating optimization (AO) is proposed to obtain the passive BF weight vector of the IRS and the power allocation coefficients of users. Finally, numerical results demonstrate the superiority and robustness of proposed scheme.