5G-NR (New Radio) CSI Computation Algorithm and Performance

5G-NR specifications is release ready and it incorporates two types of channel state information (CSI) feedback procedures. A low resolution CSI feedback procedure targeting a highly efficient (low feedback overhead) SU-MIMO operation and a high resolution CSI feedback procedure targeting an optimized MU-MIMO operation (high feedback overhead). A precoder index ranges from 2-12 bits for low resolution CSI and to several hundred bits for high resolution CSI. In this paper, we propose low-complexity precoder search algorithms for both low and high resolution CSI. We also observe that the gains due to high-resolution CSI feedback is limited to channels with low to medium spatial correlation.