of 4 bits PMI payload size is supported per subband. Several 1D/2D antenna ports layouts (N g' N , N2) and oversampling factors (O, O2) are supported as listed in Table 6.15. The inter-panel co-phasing payload is configurable with two modes. Mode 1 consists of a wideband inter-panel co-phasing, has a lower payload, and supports 2- and 4-panel operation. In this mode, the total intra- and inter-panel co-phasing payload is of 2 bits per subband. Mode 2 consists of subband inter-panel co-phasing, has a higher pay- load, and supports only 2-panel operation. In this mode, the total intra- and inter-panel co-phasing payload is 4 bits per subband. 6.12.4.2.2 Type II codebooks The Type II codebook is a higher-resolution codebook compared to the Type I design. The Type II codebook is a dual-stage codebook structure up to rank 2, W = W1xW2. For 1, following precoding rank the structure is assumed: W = where W is normalized to 1. For rank 2, the following precoding structure is assumed: W = = W1W2, where the columns of W are normalized to 1/2 The first stage W1 consists of a set of L orthogonal beams (L E {2, 3, 4}) selected from the predefined oversampled 2D DFT beams for a single polarization, and beam selection is realized in wideband (WB). The second stage, W2, consists of 2L-1 beam combining coefficients for L selected beams and 2 polarizations in each layer. Generally, beam combining coefficients can be divided into phase combining and amplitude scaling quantization separately. Phase combining is configured for subband (SB) reporting, and amplitude scaling is configured to report the WB amplitude with or without the SB differential amplitude. The weighted combination of L beams is given by the following coefficients: where - bk1,kz is an oversampled 2D DFT beam - r are the two polarizations, and l can go up to two layers Prli (WB) represents the wideband beam amplitude scaling factor for beam i and on polar- ization r and layer l 6.12 5G MIMO and Beamforming Operation represents the subband beam amplitude scaling fact