Rate-Splitting Multiple Access (RSMA) is a key enabling technique for sixth-generation (6G) wireless systems due to its powerful interference management, and Reconfigurable Intelligent Surface (RIS) improves communication performance by shaping wireless propagation. However, conventional RSMA--RIS architectures employ fixed antennas, limiting spatial degrees of freedom and system performance. To address this, we propose a movable-antenna (MA) assisted RSMA--RIS framework and formulate a sum-rate maximization problem that jointly optimizes the transmit beamforming matrix, RIS reflection matrix, common-rate partition, and MA positions. After yielding a closed-form solution for common rate splitting, the problem is transformed via fractional programming (FP). Using Karush--Kuhn--Tucker (KKT) conditions, we give iterative updates for Lagrange multipliers and beamforming matrix, obtain the RIS reflection matrix via the dual problem, and determine optimal antenna positions via gradient ascent. Numerical results show that with the existence of RIS, integrating MA yields additional gains of approximately 33.3\% for SDMA and 35.6\% for RSMA.

翻译：速率分割多址接入（RSMA）凭借其强大的干扰管理能力成为第六代（6G）无线系统的关键使能技术，而可重构智能表面（RIS）通过塑造无线传播环境来提升通信性能。然而，传统的RSMA-RIS架构采用固定天线，限制了空间自由度与系统性能。为此，本文提出了一种可移动天线辅助的RSMA-RIS框架，并构建了一个联合优化发射波束成形矩阵、RIS反射矩阵、公共速率分配以及天线位置的总速率最大化问题。在推导出公共速率分割的闭式解后，该问题通过分式规划进行转化。利用Karush-Kuhn-Tucker（KKT）条件，我们给出了拉格朗日乘子和波束成形矩阵的迭代更新方案，通过其对偶问题获得RIS反射矩阵，并采用梯度上升法确定天线最优位置。数值结果表明，在RIS存在的情况下，集成可移动天线能为SDMA带来约33.3%的额外增益，为RSMA带来约35.6%的额外增益。