发表机构
School of Electrical and Electronic Engineering, Nanyang Technological University（南洋理工大学电气电子工程学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出一种基于级联智能超表面的全波域宽带MU-MIMO OFDM发射机，通过两个SIM模块在波域实现预编码和OFDM调制，无需基带处理，可提升频谱效率。
AI 中文摘要
本文提出了一种用于宽带多用户多输入多输出正交频分复用（MU-MIMO OFDM）发射机的先进实现原理，其中传统的发射端基带链在波域中被物理合成。为了设计和优化目的，这种由级联SIM结构实现的全波域宽带MU-MIMO OFDM发射机被功能性地划分为两个级联的SIM模块。第一个模块记为SIM_1，集成了符号加载和信道自适应MU-MIMO预编码，并在信道相干时间尺度上更新，将用户流映射到虚拟端口-子载波表示。第二个模块记为SIM_2，作为离线配置的采样率调制器，直接在波域中实现逆离散傅里叶变换（IDFT）和循环前缀（CP）插入。这种无基带架构建立了从信息比特到辐射的CP扩展OFDM波形的虚拟到物理的转换。为了考虑实际非理想性，SIM_2被优化以拟合理想的多端口CP-OFDM算子，其残余响应被映射到有效耦合矩阵中。然后，SIM_1以面向通信的方式优化，通过联合调整离散相移和流-子载波功率加载来最大化总频谱效率。结果证明了所提出的无基带发射机的收敛性、架构权衡、波域OFDM物化精度以及有竞争力的性能。
英文摘要
This paper proposes an advanced realization principle for wideband multiuser multiple-input multiple-output orthogonal frequency-division multiplexing (MU-MIMO OFDM) transmitters, where the conventional transmitter-side baseband chain is physically synthesized in the wave domain. For design and optimization purposes, this fully wave-domain wideband MU-MIMO OFDM transmitter implemented by a cascaded SIM structure is functionally partitioned into two cascaded SIM blocks. The first block, denoted as SIM_1, integrates symbol loading and channel-adaptive MU-MIMO precoding updated at the channel-coherence timescale, mapping the user streams to a virtual port-subcarrier representation. The second block, denoted as SIM_2, acts as an offline-configured sampling-rate modulator that materializes the inverse discrete Fourier transform (IDFT) and cyclic prefix (CP) insertion directly in the wave domain. This baseband-free architecture establishes a virtual-to-physical transition from information bits to radiated CP-extended OFDM waveforms. To account for practical nonidealities, SIM_2 is optimized to fit the ideal multi-port CP-OFDM operator, and its residual response is mapped into an effective coupling matrix. Then, SIM_1 is optimized in a communication-oriented manner by jointly adapting discrete phase shifts and stream-subcarrier power loading to maximize the sum spectral efficiency. Results demonstrate the convergence, architecture trade-off, wave-domain OFDM materialization accuracy, and competitive performance of the proposed baseband-free transmitter.
