Modular Concepts for Practical Massive MIMO Implementations

The Massive MIMO principle is becoming a standard component of 5G cellular communications. 5G New Radio (NR) supports beamforming, beam-adjustment and beam-sweeping techniques. This increases data rates and adds flexibility for resource allocation, even in lower frequency bands below 6 GHz. In this paper, we give details on a Massive MIMO prototype, which was engineered at Fraunhofer Heinrich Hertz Institute for testing of novel radio techniques. Furthermore, we show results for beamforming and beam-nulling of real measurements performed with this hardware prototype in an outdoor environment operating in the 2.6 GHz band. Finally, we evaluate the inter-beam interference in a multi-beam scenario with spatially close beams.