Rate-Splitting Multiple Access (RSMA) is a robust multiple access scheme for multi-antenna wireless networks. In this work, we study the performance of RSMA in downlink overloaded networks, where the number of transmit antennas is smaller than the number of users. We provide analysis and closed-form solutions for optimal power and rate allocations that maximize max-min fairness when low-complexity precoding schemes are employed. The derived closed-form solutions are used to propose a low-complexity RSMA system design for precoder selection and resource allocation for arbitrary number of users and antennas under perfect Channel State Information at the Transmitter (CSIT). We compare the performance of the proposed design with benchmark designs based on Space Division Multiple Access (SDMA) to show that the proposed low-complexity RSMA design achieves a significantly higher performance gain in overloaded networks.

翻译：速率分裂多址接入（RSMA）是一种用于多天线无线网络的鲁棒多址接入方案。本文研究了在下行链路过载网络（其中发射天线数量少于用户数量）中RSMA的性能。我们针对采用低复杂度预编码方案时的最优功率与速率分配进行了分析，并给出了实现最大化最小公平性的闭式解。基于推导出的闭式解，我们提出了一种低复杂度RSMA系统设计方案，用于在发射端完美信道状态信息（CSIT）条件下，针对任意数量的用户与天线进行预编码器选择与资源分配。我们将所提方案与基于空分多址（SDMA）的基准设计方案进行性能对比，结果表明，所提出的低复杂度RSMA设计方案在过载网络中实现了显著更高的性能增益。