e same as the number of downlink cell-specific reference signals antenna ports [5]. The NRS time-frequency mapping, shown in Fig. 6.11, is additionally cyclically shifted by NNcell mod6 in the frequency domain. When NRS is transmitted on two antenna ports, then the resource elements that are used for NRS on each antenna portare set to zero on the other antenna port. The narrowband physical broadcast channel (NPBCH) is encoded using a tail-biting convolutional code (TBCC) and QPSK modulated. An important point on the in-band operation concerns N ID Ncell parameter, which may be the same as the PCI for the LTE cell. This is indicated by the opeartionMode parameter in nar- rowband master information block (MIB-NB), which distinguishes between an in-band operation with same PCI as LTE and one whose identities are different. If this parameter is set to true, then NNcell and PCI are the same and the UE may assume that the number of antenna ports is the same as in the LTE cell. The channel may then be inferred from either reference signal set. In that case, LTE cell-specific reference signal (CRS) port 0 is associ- ated with NRS port 0, and CRS port 1 is associated with NRS port 1. One antenna port Two antenna ports Resource element (k, I) Not used for transmission on this antenna port Reference symbols on this antenna port /=6/=0 /=6 /=0 /=6/=0 /=6/=0 /=6/=0 Figure 6.11 NRS subcarrier mapping [2,11,19]. Internet of Things 6.3.5 Narrowband Physical Broadcast Channel The NPBCH carries the MIB-NB. The MIB-NB contains 34 bits and is transmitted over a time period of 640 ms; that is, 64 radio frames, and includes the following information: 4 bits indicating the most significant bits of the SFN, the remaining least significant bits (LSBs) are implicitly derived from the MIB-NB starting point. 2 bits representing the two LSBs of the HFN. 4 bits for the narrowband system information block type 1 (SIB1-NB) scheduling and size. 5 bits indicating the system information value tag. 1 bit representing whether access class barring is