Narrow Beam Channel Characteristics Measured on an 5G NR Grid-of-Beam Test-Bed

Massive MIMO enabling dynamic beamforming is one key component in 5G New Radio (NR). Narrow beams improve capacity by reduced interference and extend coverage by increased antenna gain. One implementation of dynamic beamforming is Grid-of-Beams (GoB) with fixed narrow beams. In this study, the per beam characteristics are measured in a full-scale micro cell deployment with a mm-wave 5G NR test-bed. It is shown that the channel characteristics are strongly dependent on reflections captured within each beam. Channel conditions such as delay spread, singular value ratio and MIMO rank differ also between adjacent beams. Reflections may even cause significant path length difference which may call for individual synchronization per beam, e.g. meaning that beams at same transmission point may not always be considered quasi co-located (QCL).