发表机构
York University（约克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文建立统一分析框架，表征RIS辅助多频网络中波束斜视与波束分裂效应，推导连续及量化相位下的峰值条件与可行性，并提出基于扰动的校正方法，提升峰值定位精度并验证求和速率增益。
AI 中文摘要
超越5G和6G系统中的多频操作使得大孔径阵列的波束方向具有频率依赖性，从而产生对可重构智能表面（RIS）至关重要的波束失准效应。当RIS相位分布在一个频率下配置但在另一个频率下照射时，反射场可能出现主瓣偏移和额外的主瓣，从而降低波束成形性能。本文针对基于均匀平面阵列的RIS，在连续和有限分辨率相位控制下，建立了一个统一的分析框架来表征这些效应。我们将波束斜视形式化为最大增益波束偏离期望的方位-俯仰角对，将波束分裂形式化为在频率失配和量化下出现额外的最大增益波束。对于连续相位RIS，我们推导了必要且充分的峰值条件，获得了闭式形式的方位-俯仰峰值族，并建立了作为频率比、入射角和配置角以及单元间距函数的可行性条件。将分析扩展到b比特相位量化，我们通过量化误差相量的傅里叶展开将量化波束图表示为谐波阵列响应的叠加，从而得到每个谐波的闭式峰值族、主导性排序和可行性条件。为了捕捉谐波叠加引起的峰值位移，我们进一步开发了一种基于扰动的校正方法，利用主导谐波曲率和残余谐波梯度，无需穷举二维搜索即可提高峰值位置精度。数值模拟验证了分析结果，量化了峰值偏差和波束分裂概率，并展示了在多RIS、多用户、多频段网络中通过包含解析预测的斜视/分裂和谐波候选而实现的求和速率增益。
英文摘要
Multi-frequency operation in beyond-5G and 6G systems renders the beam directions of large-aperture arrays frequency-dependent, giving rise to beam misalignment effects critical for reconfigurable intelligent surfaces (RISs). When an RIS phase profile is configured at one frequency but illuminated at another, the reflected field may exhibit main-lobe deviation and additional dominant lobes, degrading beamforming performance. In this paper, we develop a unified analytical framework to characterize these effects for uniform planar array-based RISs under both continuous and finite-resolution phase control. We formalize beam-squint as the deviation of the maximum-gain beam from the desired elevation-azimuth angle pair and beam-split as the emergence of additional maximum-gain beams under frequency mismatch and quantization. For continuous-phase RISs, we derive necessary and sufficient peak conditions, obtain closed-form elevation-azimuth peak families, and establish feasibility conditions as functions of the frequency ratio, incidence and configuration angles, and element spacing. Extending the analysis to b-bit phase quantization, we express the quantized beampattern as a superposition of harmonic array responses via Fourier expansion of the quantization-error phasor, leading to closed-form per-harmonic peak families, dominance ordering, and feasibility conditions. To capture peak displacement induced by harmonic superposition, we further develop a perturbation-based correction leveraging dominant-harmonic curvature and residual-harmonic gradients, improving peak-location accuracy without exhaustive two-dimensional searches. Numerical simulations validate the analysis, quantify peak deviations and beam-split probabilities, and demonstrate sum-rate gains by including analytically predicted squinted/split and harmonic candidates in multi-RIS, multi-user, multi-band networks.
CommentsThis paper has been accepted for publication in IEEE journals
