Frequency Dependence of Measured Massive MIMO Channel Properties

A multi-user massive MIMO measurement campaign is conducted to study the channel propagation characteristics (e.g. user correlation, sum of eigenvalues and condition number), focusing on the stability over frequencies and the impact of the array aperture. We use 3 arrays with 64 antennas (6m linear array, 2m linear array and 25cm by 28cm squared 2D array) serving 8 users holding a handset with 2 antennas. The study of the measurements shows that the propagation characteristics of the channel are stable for all the measured frequencies. We also observe that user proximity and user handgrip reduce the dispersion of the studied properties of the channel across frequencies, and in such cases the larger the aperture of the array is, the less dispersed the properties are. Increasing the number of base station antennas improves the propagation characteristics of the channel and stabilizes the properties in the frequency domain.

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