NB-IoT basics: part 1 versions

NB-IoT is one of two 5G LPWAN standards (the other is called LTE CAT-M1). NB-IoT and LTE-M have excellent energy consumption and power-saving features; they are great for saving a lot of energy compared to other cellular standards. There are different technologies and functions within each of these two to do that.

If you have a sensor or a water meter, you don’t want to change the battery for at least ten years; these technologies are incredible. These technologies also have better coverage than other cellular standards; they have mechanisms to have a better range than other cellular technologies. At the same time, the devices that meet these standards are less complex than standard devices, and they only have one external antenna. They are smaller and cheaper than other cellular devices, making them a technology to use when you want to scale. These two technologies are called massive IoT technologies; they can cope with more devices in the same cell compared to standard cellular 4G or 5G technologies. 3GPP standardized these two technologies; they’re also supported by GSMA and are part of the 5G family. Therefore they are future-proof; they will be here for a long time. In a series of blog posts I will publish more information on NB-IoT that I think is missing from the general descriptions of the standard.

NB-IoT basic characteristics

NB-IoT is not a 5G standard designed to offer millisecond latency; it exists to meet a need for low-cost and low-power designs rather than time-critical designs. NB-IoT solutions typically use cheaper chipsets than other 4G/5G technologies. In combination with low cost, they also offer long battery life. In addition, the NB-IoT design objective was to improve coverage over GSM. The improvement would be 20 dB, which is significant. At the same time, the NB-IoT terminals’ maximum uplink transmit power (23 dBm) is 10 dBm lower than that of GSM terminals, thanks to which it draws considerably less energy but has better coverage as well.

Different versions of NB-IoT

Each new version of the 5G standards from 3GPP is called a release. The first release to impact NB-IoT was release 13, under the 4G standard. If you look at the market today, many of the devices meet release 13 but not any later releases. Release 13 is sometimes referred to as NB1, and in that release, the two main features introduced were a power saving mode (PSM) and enhanced discontinuous reception (eDRX), more on these below. NB2, or release 14, included several improvements over release 13, such as increased roaming/handover capabilities, multiple power-saving output levels, and increased positioning capabilities.

In release 15, the main improvements were Wake-up Signals (WUS) and BEST (Battery Efficiency Security for low Throughput). So now we may have spiced it up with even more abbreviations, but that’s why I compiled this blog post, so more information on what it means follows in a later post.

Release 16 had nothing to do with NB-IoT. The latest version of NB-IoT at the time of this publication is release 17, and that version has only one enhancement for NB-IoT, non-terrestrial networks. It is not about ET phoning home but rather about providing 5G coverage in the oceans and remote areas not currently covered by terrestrial base stations by introducing support for 5G from satellites.

Let’s now address the various technical aspects of NB-IoT, but before we start, it is helpful if you are familiar with the terms dB and MCL, link loss or link budget (three difficult words that mean roughly the same thing). These abbreviations we will not delve into these here.

Different output power levels

NB-IoT has three output power levels, 14 dBm, 20 dBm and 23 dBm, that are decided by several factors. Release 13 devices can only use 20 and 23 dBm. NB2 thus has a mode where it can go into a more low-power mode than NB1. However, this only applies when the distance to the base station is short.

In my next post, we will discuss battery life and energy consumption.