AI 中文总结
研究双向K用户干扰信道借助无源RIS实现无干扰传输的问题，利用无线信道高维随机特性，在凸几何框架下建立条件，刻画不完美信道信息影响，验证理论，为解决该信道干扰问题提供方法。
AI 中文摘要
干扰是无线网络的基本性能瓶颈，可重构智能表面（RIS）是一种有前景的干扰缓解技术。本文研究在双向K用户干扰信道中借助无源RIS能否实现无干扰传输（从自由度角度），该信道干扰严重。结果表明答案是肯定的。实现此目标面临两个挑战：RIS反射系数的单位模约束及直射和反射信道强度差异。利用无线信道的高维随机特性，在高维凸几何框架中解决问题，建立实现无干扰自由度所需RIS元素数量的充分必要条件且二者在阶数上一致，还刻画了不完美信道状态信息对可实现自由度的影响，仿真结果验证了理论发现。
英文摘要
Interference constitutes the fundamental performance bottleneck in wireless networks. Meanwhile, reconfigurable intelligent surface (RIS) has emerged as a promising technique for interference mitigation by directly modifying wireless channels. In this paper, we are interested in the following problem: whether \textit{interference-free} transmission (in terms of Degree-of-Freedom, DoF) can be achieved with the aid of passive RIS in the two-way K-user interference channel, which is regarded as the most severely interfered network. We show that the answer is affirmative, i.e., interference in this network can be neutralized over the air. To accomplish this goal, two prominent challenges arise: i) the unit-modulus constraint on each RIS reflecting coefficient; ii) the significant disparity between the strengths of the direct and reflective channels. To address these challenges, we exploit the high-dimensional and random nature of wireless channels. Specifically, we cast the problem within a high-dimensional convex geometric framework, which enables us to leverage the ubiquitous \textit{concentration} phenomenon in high-dimensional spaces. Based on this framework, we establish both sufficient and necessary conditions on the required number of RIS elements to achieve interference-free DoF, which turns out to \textit{coincide} in order sense. Furthermore, we characterize the impact of imperfect channel state information (CSI) on the achievable DoF and show that interference-free DoF remains achievable if the CSI error is below a certain threshold. Simulation results validate our theoretical findings.
