Space-Time Domain Power Spectrum Measurement and Modeling of UMi O2I Channel at 3.5 GHz

Signal coverage in the outdoor-to-indoor (O2I) scenario using the sub-6 GHz (sub-6G) frequency band is an important research topic and network deployment issue for the fifth generation (5G) mobile communication system. In this paper, we present a field measurement campaign in a typical urban microcell (UMi) O2I scenario. The base station (BS) was installed on the top of a five-story building and the user equipment (UE) was located at 38 positions in a room and four corridors on the seventh floor in a modern apartment building. By using two ±45° polarized antenna arrays, we measured the multipath propagation parameters in both polarizations in the O2I channels, including the azimuth/elevation of arrival (AoA/EoA), delay, and power of every multipath component (MPC). Based on the small-scale parameters of the MPCs, we obtained the angular power spectrum (APS) and power delay profile (PDP) of the radio channel at each measurement position. Furthermore, we propose a bottom-lifted Laplace (BL-Laplace) distribution to model APS and a shifted-exponential decaying (SED) model for PDP. We also find that the delay spread (DS) follows the Lognormal distribution. The channel measurement data and models established in this paper can provide reference for the deployment of the 5G network for the O2I coverage using the sub-6G band.