ld identifies the common search space of initial downlink BWP [13]. The RMSI is transmitted via the PDSCH by downlink assignment in an RMSI CORESET. The concept of CORESET was introduced in NR to identify a set of time-frequency resources consisting of multiple resource blocks in the frequency domain and one to three OFDM symbols in the time domain. The NR enables UE to be configured with multiple CORESETs, and each CORESET is associated with a UE-specific configured resource map- ping scheme. The PBCH payload size is 56 bits including 24-bit CRC. In NR, PBCH uses a single- antenna port transmission scheme, using the same antenna port as PSS and SSS within the same SS block. The periodicity of PBCH is 80 ms. The MIB data arrive at the PBCH pro- cessing unit in the form of one transport block (TB) every 80 ms and goes through the fol- lowing steps as shown in Fig. 4.9: payload generation, scrambling, TB CRC calculation and attachment, channel coding, and rate matching. The coded and modulated bits of PBCH are New Radio Access Physical Layer Aspects (Part 2) 435 MIB bits BCH data 1stscrambling stage with PBCH payload generation Scrambling TS 38.212 Section 7.1.1 TS 38.211 Section 7.3.3.1 cell ID m = SFN/2 mod 4 Scrambled bits + CRC scrambling Modulation TS 38.212 Section 7.1.2 TS 38.211 Section 7.3.3.2 Polar coding CRC attachment Resource element mapping TS 38.212 Section 7.1.3 TS 38.211 Section 7.3.3.3/7.4.3 Coded Bits bo,b,, Channel coding 2nd scrambling stage with cell ID TS 38.212 Section 7.1.4 n = (SSB time index) mod 4 n = (SSB time index) mod 8 do,d1,...,NN-1 Scrambled bits Rate matching TS 38.212 Section 7.1.5 fo,f1,...,FE-1 Figure 4.9 Physical layer processing of PBCH and mapping to time-frequency resources [5]. mapped onto the resource elements allocated for PBCH. As we will discuss later, the PBCH content is encoded using the polar code. Two scrambling operations are performed on PBCH which include one before CRC attachment and another one after the polar coding and rate matching. In the first scrambling