The NPDSCH channel transports unicast data from an eNB (base station) to an NB-IoT device.

The NPDCCH is used to carry DCI (Downlink Control Information).

Demodulation Reference Signal (DMRS) is always linked to NPUSCH.

Narrowband Reference Signal (NRS) is used for cell search and initial system acquisition. It's utilized to allow the device to estimate the downlink channel.

The Narrowband Secondary Synchronisation Signal (NSSS) provides time and frequency synchronisation of user equipment in a cellular network.

NB-IoT Physical Broadcast Channel (NPBCH) is used to carry MIB information to the device in the downlink by eNB (base station).