AI 中文总结
针对发射机原生T-RIS的三混合MU下行传输，本文提出统一建模与预编码框架，通过两级求解器实现WSR最大化，仿真验证其可提升WSR并抑制混合场跨域泄漏。
AI 中文摘要
集成到发射机中的透射型可重构智能表面（T-RIS）为实现三混合多输入多输出（MIMO）提供了可行方案，其中空间处理分布在数字、模拟射频（RF）和电磁（EM）域。然而，与传统RIS辅助链路不同，发射机原生T-RIS直接参与辐射形成，这使得在实际硬件约束下，T-RIS前端建模和面向加权和速率（WSR）的联合预编码极具挑战性。本文针对发射机原生T-RIS三混合多用户（MU）下行传输，提出了统一建模与预编码框架。具体而言，从连续场描述出发，接收场通过馈电阵列、可编程T-RIS孔径与用户侧传播之间的相互作用来表征，进而得到MU预编码的级联基带输入输出模型。此外，该模型在菲涅耳、夫琅禾费及混合场域中均有实例化，可在同一前端模型中处理近场聚焦与远场波束转向。进一步，在功率和量化约束下，针对数字预编码器、模拟网络和T-RIS系数，构建了WSR最大化问题。通过将外层加权最小均方误差（WMMSE）更新与WMMSE诱导的孔径场成形及硬件投影耦合，开发了两级求解器。仿真验证了建模精度与收敛性，结果表明，所提全三混合设计相较于基线方案提升了WSR，同时抑制了混合场跨域泄漏。
英文摘要
Transmissive reconfigurable intelligent surfaces (T-RISs) integrated into the transmitter provide a viable realization of tri-hybrid multiple-input multiple-output (MIMO), where spatial processing is distributed across the digital, analog radio-frequency (RF), and electromagnetic (EM) domains. However, unlike conventional RIS-assisted links, a transmitter-native T-RIS directly participates in radiation formation, making T-RIS front-end modeling and weighted sum-rate (WSR)-oriented joint precoding challenging under practical hardware constraints. This paper develops a unified modeling and precoding framework for transmitter-native T-RIS tri-hybrid multi-user (MU) downlink transmission. Specifically, starting from a continuous-field description, the received field is characterized by the interaction among the feed array, the programmable T-RIS aperture, and the user-side propagation, leading to a cascaded baseband input-output model for MU precoding. Furthermore, the same representation is instantiated in the Fresnel, Fraunhofer, and mixed-field regimes, so that near-field focusing and far-field angular steering can be handled within one front-end model. Additionally, a WSR maximization problem is formulated over the digital precoder, analog network, and T-RIS coefficients under power and quantization constraints. A two-level solver is then developed by coupling outer weighted minimum mean-square error (WMMSE) updates with WMMSE-induced aperture-field shaping and hardware projection. Simulations validate the modeling accuracy and convergence, and show that the proposed full tri-hybrid design improves WSR over baselines while suppressing mixed-field cross-regime leakage.
