 same block index on the same center frequency location which are quasi-co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and spa- tial RX parameters (when applicable) [6]. 4.1.5 Physical Downlink Shared Channel The downlink physical layer processing of transport channels consists of several steps as shown in Fig. 4.34 including CRC calculation and attachment to the TBs where a 24-bit CRC for payloads larger than 3824 bits or otherwise 16-bit CRC is attached; code block segmentation and code block CRC attachment; channel coding based on LDPC codes; physical-layer HARQ processing and rate matching; bit-interleaving; modulation; layer mapping and precoding; and mapping to assigned resources and antenna ports. At least one symbol with DM-RSs is present on each layer in which PDSCH is transmitted to a UE. The number of DM-RS symbols and RE mapping is configured by the RRC parameters. The PT-RS may be transmitted on additional symbols to aid receiver phase tracking. As shown in Fig. 4.34, in the first stage of PDSCH processing, the entire TB ao, a1 ANTB-1 is used to calculate the CRC parity bits Po, p1, PLcRc-1 where and LCRC denote the (TB) payload size and the number of CRC parity bits, respectively. The number of parity bits is set to 24 and the CRC generator polynomial gCRC24A(D) = [D24 D23 + D18+D17 D14 + D11 D10 + D7 + D6 + D5 + D4 + D3 D + 1] is used, however, if NTB 3 8824, LCRC is set to 16 bits and the generator polynomial gCRC16(D) = [D16 + D12 + D5 + is used. The output bits following the CRC attachment denoted by bo, b1, bB-1 where B = NTB + LCRC. For initial transmission of a TB with coding rate R, which is determined by the MCS index contained in the DCI, and the retrans- missions of the same TB, each code block of the TB is encoded with LDPC base graph 2 (see the section on channel coding), if NTB VI 292, if NTB < 3824 and R VI 0.67 or if R V 0.25; otherwise, LDPC base graph 1 is used as depicted in Fig. 4.35. As shown in Fig. 4.35, the maximum size of