Performance analysis of rate-splitting multiple access in intelligent reflecting surface-assisted uplink hybrid satellite-terrestrial networks

In this paper, we investigate the performance of a rate-splitting multiple access (RSMA)-based intelligent reflecting surface (IRS)-assisted uplink hybrid satellite-terrestrial network. We consider three different scenarios based on the channel phase knowledge at the IRS, namely, the ideal, partial, and blind cases. In the ideal case, the IRS has full knowledge of both the user-to-IRS and IRS-to-satellite channel phase information. In the partial case, the IRS has only the user-to-IRS channel phase information. Last, in the blind case, the IRS has no any knowledge of the phase information. We assume that the user-to-IRS channel follows Rician fading, and the IRS-to-satellite channel follows the shadowed Rician fading. The closed-form tight outage probability expressions for all three scenarios are derived. The accuracy of the derivations is confirmed by simulation results. In addition, it is shown that the performance of the RSMA-based system is superior to those of the conventional non-orthogonal and orthogonal multiple access-based systems with a small number of reflecting elements at high target rates.