Narrowband IoT – connectivity for special requirements (part 1)

This blog post is the first part of a series dealing with narrowband IoT and the special features that it entails when it comes to data transmission. In this part, I will introduce the technology as well as indicators that speak for or against the use of narrowband IoT.

The Narrowband IoT (NB-IoT) mobile radio standard will be available nationwide in Germany from 2021 and rightly carries the suffix ‘IoT’ in its name. This technology enables field devices such as gas, water and electricity meters or parking sensors to be connected to the cloud cost-effectively, even in inhospitable and difficult-to-access environments – at least once the initial hurdles have been overcome.

What is NB-IoT?

Low-power wide-area network (LPWAN) technologies have become increasingly widespread in recent years. Low-range wide-area network (LoRaWAN) should also be mentioned here in addition to NB-IoT. While LoRaWAN requires special gateways to communicate, NB-IoT uses the mobile radio network for communication and will be available nationwide in Germany by 2021.

The physical properties of this mobile radio standard enable data to be transmitted at low transmission rates of up to 159 kbit/s at low frequency (800 or 900 MHz). And it does so with while consuming less energy than conventional devices that also operate in the LTE spectrum.

This means that traditional use cases for narrowband IoT lie in the areas of smart metering, building automation and tracking. One potential scenario is the hourly or daily transmission of readings from an electricity meter in the basement of a residential building. This does not require large amounts of data to be transmitted, nor does it require the data to be transmitted quickly – but it does require good building penetration, which conventional mobile radio technology, such as LTE, does not provide due to its high frequency of up to 2,600 MHz.

NB-IoT solutions have very low energy requirements in addition to very good building penetration. This means that other traditional use cases lie in the areas of smart cities and logistics – that is, use cases that see devices installed in places that are difficult to access or not accessible to the public without an external power supply. If these have to be regularly maintained or, for example, batteries have to be replaced on site by a technician, then this effort is justifiable for a few units, but if several hundred or thousand units are involved, this approach no longer scales.

Is my scenario suitable for NB-IoT?

In addition to a number of reasons that speak for the use of narrowband IoT as a communication channel, there are also some aspects that can prevent it from being used. These include:

• Data volume: NB-IoT tariffs are usually designed to transmit a few hundred megabytes over several years. With battery-powered devices in particular, transmitting larger amounts of data drastically reduces battery life. A transmission technology such as LTE-M may be more suitable provided there are no restrictions in this case (for example due to network operation).
• Data rate: NB-IoT is unsuitable if high-frequency data transmission is required because the readings need to be available in the cloud in real time.
• High availability from the cloud: If the device is battery-powered, the module should switch to standby mode when no active data is being received or sent in order to save energy. NB-IoT should not be used if the use case rules this out as an option because it must be possible to control the device from the cloud at any time.

NB-IoT can be considered as a possible transmission path if the criteria do not include large data volumes, frequent transmissions or immediate availability from the cloud.

What needs to be considered?

Various other factors must be taken into account to be able to use NB-IoT sensibly – be it with regard to limited data quotas of mobile phone contracts or the economical use of battery-powered end devices – without neglecting relevant aspects such as security.

I will address these challenges and how to overcome them in the second part of my blog series on narrowband IoT.

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