AI 中文总结
该研究针对流体天线系统，在无空间协方差先验条件下，基于Clarke各向同性散射模型确定了全端口CSI重建的可行性阈值，推导了相关参数权衡关系，实现了少端口的可扩展无先验CSI重建。
AI 中文摘要
流体天线系统（FAS）利用大量候选端口实现空间分集，但硬件限制仅能在少数活跃端口获取信道观测值。是否可在无预先获取的信道统计信息时重建全端口信道状态信息（CSI）仍是待解决问题。在Clarke各向同性散射模型下，研究表明信道位于由散射环境而非总端口数决定的低维空间模态子空间中。因此，当观测端口数达到模态维度（即M≥r）时，即使M远小于N，重建也可行。进一步确定了严格的可行性阈值：低于该维度时无论信噪比（SNR）如何均无法可靠重建，高于该维度时精度随额外观测值提升。通过将重建误差分解为模态截断、估计和学习分量，推导了射频（RF）链、导频开销、发射功率与训练数据间的明确权衡关系。这些成果实现了仅用少数活跃端口即可进行可扩展的无先验全端口CSI重建。
英文摘要
Fluid antenna systems (FASs) exploit many candidate ports for spatial diversity, but hardware constraints allow channel observations at only a few active ports. Whether full-port CSI can be recovered without pre-acquired channel statistics remains open. Under the Clarke isotropic scattering model, we show that the channel lies in a low-dimensional spatial modal subspace determined by the scattering environment rather than the total port count. Consequently, recovery becomes feasible when the number of observed ports reaches the modal dimension (i.e., $M\geq r$), even when $M\ll N$. We further establish a sharp feasibility threshold: reliable recovery is impossible below this dimension regardless of SNR, whereas accuracy improves with additional observations above it. By decomposing the recovery error into modal truncation, estimation, and learning components, we derive explicit tradeoffs among RF chains, pilot overhead, transmit power, and training data. These results enable scalable prior-free full-port CSI recovery with few active ports.
