LAUSR

Transmissive reconfigurable intelligent surfaces (RISs) are a promising solution for coverage enhancement of the future outdoor-to-indoor (O2I) millimeter wave (mmWave) network. In this work, the coverage probability of the multiple transmissive RIS-aided O2I mmWave network is investigated. Firstly, the system model of the three-dimensional O2I mmWave network considering random blockages is proposed. Moreover, the spatial correlation of blockages is analyzed to derive the accurate blockage probability. Furthermore, based on the blockage probability, the closed-form approximation of the signal-to-noise ratio (SNR) coverage probability is derived and verified. Finally, the impact of blockage density, the number and locations of RISs on the coverage probability is analyzed. According to the numerical results, the highest coverage enhancement caused by four small-scale RISs with appropriate locations reaches 69.5% higher compared with a large-scale RIS located at the center of the building envelope.