repeated to form an extended bitmap (bo, b1, bLPsscH~1) where bj = bjmodNTRP covers entire PSSCH subframe pool. The subframes used for PSSCH transmission are selected by PSSCH values in this extended bitmap to obtain the final subframe set denoted by n1 PSSCH NPSSCH-1 ,PSSCH where NPSSCH value is a multiple of 4, and denotes the num- ber of subframes that can be used for PSSCH transmission in the PSCCH period. This is consistent with the fact that each TB transmitted within this interval will be sent four times using the fixed HARQ redundancy version sequence (0,2,3,1) [5]. 828 Chapter 7 7.4.2.3 Physical Sidelink Discovery Channel In LTE-based sidelink communication, the processing of the SL-DCH follows the downlink shared channel with the following differences: (1) data arrives at the channel coding unit in the form one TB per each transmission time interval; (2) in the step of code block concate- nation, the sequence of coded bits corresponding to one TB after code block concatenation is referred to as one codeword; and (3) PUSCH interleaving is applied without any control information in order to apply a time-first rather than frequency-first mapping such that block b(0), b(Nbit - -1), where Nbit is the number bits transmitted on the PSDCH in one subframe, are scrambled with the scrambling sequence generator initialized with Cinit = 510 at the start of each PSDCH subframe and then QPSK-modulated. The layer mapping, transform precoding, precoding, and the mapping to the physical resources are similar to PSCCH processing described earlier. 7.4.2.4 Physical Sidelink Broadcast Channel Fig. 7.25 shows the processing stages of SL-BCH transport channel in LTE-based sidelink communication. The broadcast channel data in a TB is processed through channel coding module, which includes CRC attachment to the TB, channel coding, and rate matching. Since the latter processing is in the uplink direction of LTE, following the rate matching, LTE PUSCH interleaving is used without multiplexing with control information. A time- fi