TX) indication bits interleaving radio frame segmentation The UMTS Network and Radio Access Technology CRC attachment CRC attachment TrBk concatenation / TrBk concatenation / Code block segmentation Code block segmentation Channel coding Channel coding Rate matching Rate matching Radio frame equalization 1st insertion of DTX indication 1st interleaving 1st interleaving Radio frame segmentation Radio frame segmentation Rate matching Rate matching TrCH Multiplexing S1,S2,S35....SS TrCH Multiplexing 2nd insertion of DTX indication CCTrCH CCTrCH Physical channel Physical channel segmentation segmentation 2nd interleaving 2nd interleaving Physical channel mapping Physical channel mapping Uplink Downlink (applies to TDD) Figure 4.49 FDD uplink and downlink transport channel multiplexing structure. The UTRA Physical Layer Design multiplexing of transport channels physical channel segmentation mapping to physical channels Figure 4.49 illustrates the coding/multiplexing steps for FDD uplink and downlink. Clearly, the uplink also applies to the TDD mode. Hence the uplink description will basically cover the needs for the TDD. However, as mentioned above we will highlight where differences exist. We should also note here that in this section for consistency we keep the structure and nomenclature of the technical specifications by incorporating direct extracts and using the same type of equations. Note: In the downlink we denoted Coded Composite Transport Channel (CCTrCH) the single output data stream from the TrCH multiplexing, including DTX indication. This CCTrCH can get mapped to one or several physical channels. 4.6.1 Error Detection and CRC Calculations In the sequel we cover the DL and UL in an integrated manner by indicating differences where appropriate. Cyclic Redundancy Check (CRC) affords error detection on transport blocks. Higher layers signal what CRC (24, 16, 12, 8 or 0) bit length shall be used for each TrCH. We use the entire transport block to calculate the CRC parity bits for each transport block. The fol