MIMO & beamforming optimization: rank adaptation, CSI reporting, codebook

Rank Adaptation and MIMO Layers

MIMO and beamforming are the primary throughput multipliers in 5G NR. Proper configuration significantly impacts achievable data rates and spectral efficiency. Rank adaptation controls how many spatial layers are used simultaneously. A UE supporting 4x4 MIMO can theoretically use up to 4 layers, but actual rank depends on channel conditions. In strong SINR with rich scattering (urban environments with reflections), rank 3-4 is achievable. In weak SINR or line-of-sight conditions (rural), rank drops to 1-2. The gNB adapts rank based on the UE's Rank Indicator (RI) feedback. Optimization…