This letter explores the influence of an active Simultaneously Transmitting and Reflecting Reconfigurable Intelligent Surface (STAR-RIS) in supporting Cooperative Rate Splitting Multiple Access (C-RSMA) in a downlink wireless network. We consider a scenario where a base station (BS) with multiple antennas utilizes the active STAR-RIS to aid weak and strong users. Strong users also serve as full-duplex relays to transmit the common stream to weak users. By jointly optimizing BS beamformers, active STAR-RIS reflection and transmission, stream split, and strong users’ transmit power, we maximize the network sum rate while satisfying minimum rate requirements, active STAR-RIS hardware constraints and power budgets at the BS, the active STAR-RIS and at each strong user. An alternating optimization algorithm employing successive convex approximation is proposed, and simulations showcase its significant gains over baseline approaches.

中文翻译：

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用于主动 STAR-RIS 辅助下行链路通信的协作速率分路多址


本信探讨了有源同步发射和反射可重构智能表面 （STAR-RIS） 在支持下行链路无线网络中的协作速率拆分多址 （C-RSMA） 方面的影响。我们考虑这样一种情况：具有多个天线的基站 （BS） 利用有源 STAR-RIS 来帮助弱用户和强用户。强用户还充当全双工中继，将公共流传输给弱用户。通过共同优化 BS 波束成形器、主动 STAR-RIS 反射和传输、分流和强用户的发射功率，我们最大限度地提高了网络总和速率，同时满足 BS、主动 STAR-RIS 和每个强用户的最低速率要求、主动 STAR-RIS 硬件约束和功率预算。提出了一种采用连续凸近似的交替优化算法，仿真表明其相对于基线方法的显著优势。