NB-IoT is a cellular standard from 3GPP for low-power devices that send small amounts of data over existing mobile networks.
NB-IoT (Narrowband IoT) is a low-power wide-area cellular technology standardised by 3GPP in Release 13 in 2016. It runs on licensed mobile spectrum, so the network is built and run by mobile operators, and each device uses a SIM like a phone. NB-IoT uses a narrow channel of 180 kHz, which can sit inside an LTE carrier, in its guard band, or on its own. It is designed for devices that send short messages now and then. Two power-saving features help batteries last: power saving mode, in which the device sleeps for long periods while staying registered on the network, and extended discontinuous reception, which spaces out the times it listens. Coverage enhancement repeats transmissions so the signal can reach places deep indoors or underground, at the cost of more energy per message. In water, NB-IoT is used for smart water meters, pressure and flow loggers in pipe networks, and level sensors in tanks and wells. For example, a meter in a basement chamber can send one message a day holding 24 hourly readings through the nearest mobile mast, with no gateway owned by the utility. Its strengths are wide coverage where operators have rolled it out, good reach into buildings, security from the mobile network, and no need for the utility to run its own radio network. Its limits are that coverage depends on the operator, each device usually carries a subscription fee, and the operator can change or switch off the network during the life of a meter. Devices at the edge of coverage use many repeats and drain the battery faster. NB-IoT is not suited to moving devices or large data volumes. Many projects compare it with LoRaWAN on cost, coverage and control before choosing.