Massive MIMO channels — Measurements and models

Spatial multiplexing using Massive MIMO has been shown to have very promising properties, including large gains in spectral efficiency and several orders of magnitude lower transmit power, as compared to today's access schemes. The properties of massive MIMO have been studied mostly for theoretical channels with independent and identically distributed (i.i.d.) complex Gaussian coefficients. To efficiently evaluate massive MIMO in more realistic scenarios, we need channel models that capture important massive MIMO channel characteristics. We pursue this by analyzing measurement data from a measurement campaign in the 2.6 GHz frequency range, using a physically large array with 128 elements. Key propagation characteristics are identified from the measurements. We use the cluster-based COST 2100 MIMO channel model as a basis, and propose an extension to include those important propagation properties for massive MIMO. Statistical models of the total number of clusters, their visibility regions and visibility gains at the base station side are found based on the measurement data.