 MIMO technology has been the key driver to achieve ever-higher spectrum efficiency in mobile communications. The network can use analog beamforming, digital beamform- ing, or hybrid beamforming for Physical Downlink Control Channel (PDCCH) and/or Physical Downlink Shared Channel (PDSCH) transmissions; and different beam widths can be used for the PDCCH and PDSCH, for example, a wide beam for the PDCCH to achieve good coverage, and narrow beams for the PDSCHs to allow MU-MIMO opera- tions. However, improving spectrum efficiency alone is not sufficient to deliver the tar- geted user and system throughputs in NR; a large channel bandwidth or large aggregated channel bandwidths is/are needed, which are more readily available at higher frequen- cies, for example, mmW. Hence, the support for mmW is an important feature of NR. Lessons learned in LTE have driven many design aspects of 5G NR. In LTE, the Cell-specific Reference Signal Common Reference Signals (CRS) serves multiple pur- poses. Considering those relevant for PDSCH reception, they include: timing-frequency synchronization for idle state UEs, fine-timing frequency synchronization for connected mode UEs, channel estimation for PDCCH demodulation, for the PDSCH, and for Channel State Information (CSI) acquisition.2 With SO many functionalities depending on CRS, it is therefore always ON at the prescribed occasions, no matter what the loading situation in a cell may be. In 5G NR, those functionalities are handled not by one signal as in LTE but instead by different signals: PDCCH Demodulation Reference Signal (DMRS), PDSCH DMRS, CSI-RS for beam management, CSI-RS for CSI acqui- sition, and CSI-RS for tracking. Consequently, the density/frequency of each signal can be configured separately in a flexible way, for example, by considering interference to other cells, base station/UE power consumption, and latency. While good for the 5G NR radio efficiency itself, such flexibility comes at the cost of additional UE implementation complexity. For example, the PDCCH w