ts for approximating the channel eigenvector with a linear combination of the basis subsets. It must be noted that while beam management and CSI acquisition can be independently operated, they can be used together to support mobile UEs. For UEs in RRC_CONNECTED state, in addition to the SS block, UE-specific CSI-RS can be configured in order to improve the quality of UE measurements and to provide better user- centric mobility experience. For example, in high-frequency bands, narrow-beam CSI-RS can be configured for the UEs at the edge of the cell in order to achieve better signal-to-interfer- ence-plus-noise ratio (SINR) range and measurement accuracy. As shown in Fig. 4.41, New Radio Access Physical Layer Aspects (Part 2) 501 Cell 2 Cell 1 NR SS block handover CSI-RS boundary SS block Figure 4.41 Configurable CSI-RS for downlink mobility measurements [72]. assuming the same energy per resource element (EPRE) is applied to CSI-RS and SSB resources for transmission, narrow-beam CSI-RS measurement can provide better SINR range which can improve RSRP measurement accuracy compared to wide-beam SSB measurements. The CSI-RS properties of the serving and neighboring cells for the mobility measurements can include NR cell ID, slot configuration used to obtain the slot offset for CSI-RS and the periodicity, for example, 5, 10, 20, 40 ms, configurable measurement bandwidth of CSI-RS, configurable parameter for CSI-RS scrambling sequence, configurable numerologies, and association between CSI-RS for mobility measurement and SSB, such as spatial QCL information. The above CSI-RS properties are signaled to the UE via dedicated RRC signaling [72]. Two antenna ports are said to be quasi co-located, if the properties of the channel over which a symbol on one antenna port is transmitted can be inferred from the channel over which a symbol on the other antenna port is transmitted. The QCL supports beam management (spatial parameter), frequency/timing offset estimation (Doppler/delay), and RRM measurements (average gain). The refe