Capacity Analysis of Massive MIMO on High Altitude Platforms

With Massive MIMO installed on High Altitude Platforms (HAPs), capacity analysis is conducted for both sparse users and hotspot users. Sparse users are assumed to follow the Poisson Point Process and their capacities are obtained via the random geometry theorem. For hotspot users, Massive MIMO combined with HAP-based communication is shown to be able to achieve the multiplexing gain thus increase the hotspot capacity. The channel correlation model of UPA under LOS propagations is obtained for users within the hotspot. An upper bound of the correlation function is further derived to show that the correlation between hotspot users can be sufficiently low, resulting in hotspot capacity improvement. The hotspot capacity is affected by location distributions of the scheduled users. Four user location distribution models are considered, which leads to the capacity upper bound, the practical schemes to implement and the capacity estimation method respectively.