On the performance of indoor multi-storey small-cell networks

Mobile data traffic has been largely generated indoors. However, indoor cellular networks have been studied either on a two-dimensional (2D) plane or as an intractable optimization problem for a multi-storey building. In this paper, we develop a tractable three-dimensional small-cell network model for a multi-storey building. On each storey, the small-cell base stations (BS) are distributed following a 2D homogeneous Poisson point process. We analytically derive the downlink coverage probability, spectral efficiency (SE) and area spectral efficiency for the indoor network as functions of the storey height, the penetration loss of the ceiling and the BS density. Our tractable expressions show that a higher penetration loss of the ceiling leads to a higher coverage probability and a higher SE. Meanwhile, with the increase of the storey height or the BS density, the downlink coverage probability first decreases and then increases after reaching a minimum value, indicating that certain values of storey height and BS density should be avoided for good indoor wireless coverage.