LTE-NB: RRC
The uppermost layer on the control plane of the access stratum is radio resource control (RRC) (AS). It also transports non-access stratum (NAS) messages, which are positioned above the RRC layer. The RRC layer contains a number of information components that make up system information.
MIBs and SIBs
The Master Information Blocks (MIBs) contains the most important and often communicated system information.
NB-IoT RACH Procedure
The NB-IoT RACH procedure is a lower power state, where it can conserve its battery life by entering idle mode. The NB-IoT RACH procedure is based on the IEEE 802.11ah standard.