With the increasing adoption of millimeter-waves (mmWave) over cellular networks, outdoor-to-indoor (O2I) communication has been one of the challenging research problems due to high penetration loss of buildings. To address this, we investigate the practicability of utilizing reconfigurable intelligent surfaces (RISs) for assisting such O2I communication. We propose a new notion of prefabricated RIS-empowered wall consisting of a large number of chipless radio frequency identification (RFID) sensors. Each sensor maintains its own bank of delay lines. These sensors which are built within the building walls can potentially be controlled by a main integrated circuit (IC) to regulate the phase of impinging signals. To evaluate our idea, we develop a thorough performance analysis of the RIS-based O2I communication in the mmWave network using stochastic-geometry tools for blockage models. Our analysis facilitates two closed-form approximations of the downlink signal-to-noise ratio (SNR) coverage probability for RIS-based O2I communication. We perform extensive simulations to evaluate the accuracy of the derived expressions, thus providing new observations and findings.

中文翻译：

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RIS 建模支持毫米波蜂窝网络中的室外到室内通信


随着蜂窝网络上毫米波 (mmWave) 的日益普及，由于建筑物的高穿透损耗，室外到室内 (O2I) 通信已成为具有挑战性的研究问题之一。为了解决这个问题，我们研究了利用可重构智能表面（RIS）来协助此类 O2I 通信的实用性。我们提出了一种由大量无芯片射频识别 (RFID) 传感器组成的预制 RIS 墙的新概念。每个传感器都维护自己的延迟线组。这些内置于建筑物墙壁内的传感器可能由主集成电路 (IC) 控制，以调节撞击信号的相位。为了评估我们的想法，我们使用阻塞模型的随机几何工具对毫米波网络中基于 RIS 的 O2I 通信进行了全面的性能分析。我们的分析有助于对基于 RIS 的 O2I 通信的下行链路信噪比 (SNR) 覆盖概率进行两种闭式近似。我们进行广泛的模拟来评估推导表达式的准确性，从而提供新的观察结果和发现。