Multi-User Spatial Consistency Analysis of Outdoor Massive-MIMO Measurements

This article presents a massive multiple-input multiple-output (MMIMO) outdoor measurement campaign with bidirectional angular discrimination. Two dynamic user arrays of eight elements each are measured simultaneously. Multiuser consistency and spatial consistency are important for proper modeling and simulation of dynamic users in MMIMO channels. This article will investigate the common scatterers between two moving users by considering the power contribution from physical objects to each user. Interuser distance and user alignment in the direction of dominant scatterers are also considered. Paths are estimated from wideband dual-directional beam-scanning. A method is developed to group the paths based on delay and angular development along the measured tracks. The estimated delay and angle of each path, along with ray tracing simulations, are used to map the interactions of each path to surrounding walls or objects. The power contributions from objects are compared to determine common scatterers between users, which can cause larger correlation and a reduced MIMO capacity.