Since Massive MIMO is likely to be a major feature in 5G it is important to have accurate models to study its performance. Propagation measurements of massive MIMO in different environments are needed in order to obtain the knowledge to form and calibrate such models.
Our general objective is to make propagation measurements to improve knowledge about the channel for massive MIMO systems at frequencies around 3.5 GHz. These measurements will be done in both outdoor and indoor environments. In a potential future collaboration an outdoor-to-indoor scenario could also be measured.
The measurements will be tailored to specifically investigate the following features: users or clusters in the near-field of the array, non-stationarities across the array, and multi-user/moving user spatial consistency. As the models proposed often rely on clusters (clusters per sub-arrays, common clusters across users), a particular focus will be in the detection of clusters and therefore simultaneously direction of departure and arrival seen from idealized arrays (i.e. both the transmit and receive side perspective). Such information is important to tune the channel models geometric structure. An additional aspect that is interesting for massive MIMO is the user impact; both in shear direction sense (antenna pattern detuning and body shadowing modulating the field of view) and in terms or signal conditions (correlations, branch power differences etc).