This is enough for the minimum system information, as we described before. Those bits are channel- encoded using the polar coding scheme. In the next chapter, we will discuss further channel coding schemes that NR uses in more detail. Recall that the PBCH carries the MIB for devices to decode. The 3rd Generation Partnership Project (3GPP) describes the MIB, as shown in the following figure: Physical channels and signals for the initial access procedure systemFrameNumber BIT STRING (SIZE (6)), For SIB1 search space: 8 bits: 4 MSB + 4 LSB subCarrierSpacingCommon scs15or60, scs30or120, ssb-subcarrierOffset INTEGER (0..15), PDCCH allocation PDCCH monitoring occasions dmrs-TypeA-Position ENUMERATED {pos2, pos3}, (#RBs, #symbols, and (#search space sets, pdcch-ConfigSIB1 INTEGER (0..225), #RB offset) first symbol index, SFN, slot number) cellBarred ENUMERATED {barred, notBarred}, intraFreqReselection ENUMERATED {allowed, notAllowed}, sqare BIT STRING (SIZE (1)) 23 bits + 8 other bits* in PBCH transport block + 1 bit* + 24 bit *PBCH: **Choice parameter: CRC = 56 bits + polar coding each TTI (80 ms) + 4 LSB of SFN + 1 bit for selecting MIB or + 3 bits of SSB index messageClassExtension + 1 bit half-frame index Figure 5.15 - MIB A device gets the following information through decoding: A System Frame Number (SFN) Subcarrier spacing for initial access The SS block subcarrier offset The DMRS type A position If the cell is barred Now, we will see how the resource element mapping occurs for the PBCH. PBCH resource element mapping The following figure shows the basic processing chain for the PBCH. The payload will go through two different scrambling operations. The first one happens before encoding, whereas the second one happens after decoding. 5G Air Interface and Physical Layer Procedures - Part 2 MBI bits m = (SFN / 2) % 4 1st Scambling Cell ID (m-portion) Scrambled Polar Coding Coded bits n = (SSB time index) % 4 2nd Scrambling Cell ID n = (SSB time index) % 8 (n-portion) Scrambled bits Figure 5.16-PBCH - resource element