t fields before the gap can also get filled with DTX. Denoting the number of bits available in the TFCI fields of one com- 16 This implies that bits b30 and b31 do not get transmitted. The UMTS Network and Radio Access Technology pressed radio frame by D and the number of bits in the TFCI field in a slot by NTFCI, then we can express E, the first bit to be repeated as: E = Nfirst NTFC1 if Nfirst + TGL <15, else E = 0. (4.97) When the transmission gap does not extend to the end of the frame, then E corresponds to the number of the first TFCI bit in the slot directly after the TG. We denote the total number of TFCI bits to be transmitted by Ntot. Thus, if SF 128 then Ntot = 32, else Ntot = 128. Afterwards, the following relations define the mapping: dk=blk mod 32) wherek=0,1,2,...,min(E,Ntot)-1andifE<Ntot = (4.98) dk+D-N ===(b(k mod 32) = (4.99) DTX bits are sent on dk where = min(E,Ntot),...,min(E,Ntot) - Ntot-1 [10]. 4.6.15 Examples on Channel Coding and Multiplexing In the following we illustrate channel coding and multiplexing examples from [21] fol- lowing the principles outlined in [10,20]. The examples aim to practically show the pat- ters and fields to code different frames in the UTRA FDD and TDD modes. Thus, the number and variables in the forthcoming figures show the number of bits in the corre- sponding fields. 4.6.15.1 Downlink FDD BCH The parameters for the BCH shown in Table 4.43 indicate CRC bits, coding type, TTI, the number of codes used, ad the spreading facto (SF). Figure 4.54 illustrates the patterns of the bits in the corresponding fields of the DL FDD BCH example. Notice that we do not necessarily follow all the steps outlined in the preceding section. Thus, each particular channel will use only the corresponding steps. Table 4.43 Downlink FDD BCH Parameters Transport block size 16 bits Coding CC, coding rate = 1/2 20 ms The number of codes The UTRA Physical Layer Design Transport block CRC, and Tail attachment Convolutional coding R=1/2 Rate Matching 1st interleaving Radio frame segmentation