or for beam i on polarization r and layer l - Cr,l,i represents the phase combiner for beam i on polarization r and layer l. This is configurable between 2 and 3 bits using QPSK or 8PSK. The Type II codebook benefits from a configurable amplitude scaling mode between wideband and subband (with unequal bit allocation) and wideband only. The beam selec- tion is wideband only and consists of an unconstrained beam selection from an orthogo- nal basis. As was the case for Type I codebooks, the Type II cookbook has several 1D/2D antenna ports layouts (N , N2), and oversampling factors (O, O2) are supported as listed in Table 6.16. The Type II CSI feedback requires a large reporting overhead to acquire enhanced spatial channel information. 6.12.4.2.3 Port selection codebooks NR also supports a codebook for beamformed CSI-RS. This comes as an extension of Type II CSI for rank 1 and 2, where W1 is given as follows: where X is the number of CSI-RS ports and Le{2, 3, 4}. The possible values of X follow the Type II single-panel codebook: where - () is a length XIN vector with the i-th element equal to 1 and 0 elsewhere The port selection is given by m E € 0,1, -1} where m is wideband - The values of d is configurable d E {1, 2, 4} under the condition that Table 6.16 Type Il codebook antenna power layouts and oversampling factors. Number of CSI-RS ports (N1, N2) (O, O2) (2,1) (4,-) (2,2), (4,1) (4,4), (4,-) (3,2), (6,1) (4,4), (4,-) (4,2), (8,1) (4,4), (4,-) (6,2), (4,3), (12,1) (4,4), (4,-) (8,2), (4,4), (16,1) (4,4), (4,-) a) Beam selection is not used for 4-port L=2 and for 8-port L = 4. 6 5G Physical Layer The amplitude scaling and phase combining coefficients, along with their configurations, follow the Type II single-panel codebook. 6.12.4.3 Resource Indicators: CRI, SSBRI, RI, LI The UE can be configured with a set of nonzero-power CSI-RS resources out of which it may be asked to report a subset. The identification of such a nonzero-power CSI-RS is done by a CSI-RS resource indicator. When a UE is configured with more 