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Low Power Wide Area Networks (LPWAN): advantages and disadvantages of the leading Narrow-Band IoT and LTE Cat M1 technologies


Developers of systems intended for the Internet of Things are faced with the question as to which connection technology should be used. Anja Schaal, Product Sales Manager and wireless expert at Rutronik, explains the advantages and disadvantages of the technologies.

The various Low Power Wide Area (LPWA) technologies differ regarding network coverage, data rates, power consumption, security, scalability and interoperability. As no single technology excels in all these disciplines, the specific requirements must be established on a case-by-case basis. For if the selected technology does not suit the application, this can lead to poor performance, unnecessarily high operating costs and limited scalability - if the worst comes to the worst, a costly and complicated migration may have to be carried out.

License free LPWA variants: SigFox and LoRa (RFMCU1232, RFMCU1158, DISSYS1148)

One basic way of categorizing the technologies concerns whether they need to be licensed or not. SigFox and LoRa are the most common license-free representatives.

Their advantages:

- The modules are cheaper than those of the licensed technologies.

- No SIM cards are needed. This means that no costs can arise for administering and replacing SIM cards.

Their disadvantage:

- The infrastructure is still thinly spread. It is still in the process of being developed, and this will take some time.

So for applications that depend on reliable wireless connection with full coverage, only the licensed technologies come into question.


Licensed LPWA variants: NB-IoT and Cat-M1

Narrow-Band IoT (NB-IoT or Cat-NB1) and LTE Category M1 (aka Cat-M1 or LTE-M) use the mobile wireless network, and this makes for better scalability, service quality and security features compared with the license-free LPWA alternatives LoRa and SigFox.

NB-IoT has a lower transmission rate than Cat-M1. For downloads it is less than 250 kbps and for uploads it is less than 20 kbps. The band width is 200k Hz. This makes NB-IoT well suited for stationary applications that must operate very efficiently from the energy consumption point of view.

Network operators in Europe and Asia are backing NB-IoT. By mid-2017, Deutsche Telekom had already launched NB-IoT starter packages onto the market. In the USA the network operators favor Cat-M1, although T-Mobile will be supporting NB-IoT from 2018 onwards there as well.

Telit supplies modules for NB-IoT applications: The NE910C1 displays high energy efficiency and has an especially reliable network coverage, even in buildings. The standard xE910 form factor (28 mm x 28 mm) means that it can simply replace other modules of the same size in existing applications. Telit's NE866B1 has very similar specifications. However, thanks to its even smaller form factor (xE866, 19 mm x 15 mm), it is perfectly suited for use in very small devices.

With up to 1 Mbps, Cat-M1 has a higher data transmission rate than NB-IoT. Also, in contrast to NB-IoT, Cat-M1 supports Voice Over LTE (VoLTE) for applications involving speech transmission. As it also supports handovers from one wireless cell to another, it is also suitable for mobile and movable applications, e.g. in telematics and fleet management.

Telit also supplies corresponding modules for Cat-M1x. Telit products such as the ME910C1 have the same form factors as the NB-IoT modules. This has the advantage that any given device can accommodate whichever module is needed in a target country without the need for time-consuming and expensive redesigning.


LPWAN basics

Low Power Wide Area Networks (LPWAN) are wireless communication networks that have been developed specifically for Internet of Things (IoT) applications. This is because the cellular technologies (GSM, UMTS, LTE) are too expensive, while Short Range Networks (e.g. Bluetooth, WiFi) are too energy intensive and limited in their transmission capacity.

LPWAN, on the other hand, transmit low bit rates over long distances, which is exactly what is needed for IoT devices and systems. The reduced data transmission rates mean significantly less power consumption than other Wireless Wide Area Networks (W-WAN), making these technologies suitable for battery-operated applications as well.