Wireless networks-on-chip (WNoCs) are an enticing complementary interconnect technology for multi-core chips but face severe resource constraints. Being limited to simple on-off-keying modulation, the reverberant nature of the chip enclosure imposes limits on allowed modulation speeds in sight of inter-symbol interference, casting doubts on the competitiveness of WNoCs as interconnect technology. Fortunately, this vexing problem was recently overcome by parametrizing the on-chip radio environment with a reconfigurable intelligent surface (RIS). By suitably configuring the RIS, selected channel impulse responses (CIRs) can be tuned to be (almost) pulse-like despite rich scattering thanks to judiciously tailored multi-bounce path interferences. However, the exploration of this "over-the-air" (OTA) equalization is thwarted by (i) the overwhelming complexity of the propagation environment, and (ii) the non-linear dependence of the CIR on the RIS configuration, requiring a costly and lengthy full-wave simulation for every optimization step. Here, we show that a reduced-basis physics-compliant model for RIS-parametrized WNoCs can be calibrated with a single full-wave simulation. Thereby, we unlock the possibility of predicting the CIR for any RIS configuration almost instantaneously without any additional full-wave simulation. We leverage this new tool to systematically explore OTA equalization in RIS-parametrized WNoCs regarding the optimal choice of delay time for the RIS-shaped CIR's peak. We also study the simultaneous optimization of multiple on-chip wireless links for broadcasting. Looking forward, the introduced tools will enable the efficient exploration of various types of OTA analog computing in RIS-parametrized WNoCs.

翻译：片上无线网络（WNoC）是一种极具吸引力的多核芯片互补互连技术，但面临严峻的资源约束。由于仅能采用简单的开关键控调制，芯片封装内的混响特性限制了符号间干扰下的允许调制速度，这使人们对WNoC作为互连技术的竞争力产生质疑。幸运的是，最近通过可重构智能表面（RIS）对芯片内无线电环境进行参数化，这一棘手问题得以解决。通过合理配置RIS，即使存在丰富散射，利用精心设计的多跳路径干扰，所选信道脉冲响应（CIR）也可被调谐为（近似）脉冲形式。然而，这种"过空"（OTA）均衡的探索面临两大阻碍：（i）传播环境极其复杂，（ii）CIR对RIS配置存在非线性依赖，每次优化步骤均需进行代价高昂且耗时的全波仿真。本文证明，仅需单次全波仿真即可标定RIS参数化WNoC的简化基物理一致性模型。由此，我们无需任何额外全波仿真即可近乎瞬时预测任意RIS配置下的CIR。借助这一新工具，我们系统探索了RIS参数化WNoC中OTA均衡的相关问题，包括RIS成形CIR峰值延迟时间的最优选择，以及广播场景下多个片上无线链路的联合优化。展望未来，所引入的工具将能高效探索RIS参数化WNoC中各类OTA模拟计算方案。