NB-IoT vs LTE-M (CAT-M) for your IoT project

NB-IoT vs CAT-M

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What is NB-IoT?

NB-IoT is a standards-based LPWAN that enables a range of new IoT devices and services. In some cases, it reduces power consumption and improves system capacity and spectrum efficiency, especially in deep coverage, remote, and hard-to-reach locations.

NB-IoT also minimizes device complexity. The underlying technology is much simpler than GSM/GPRS and can co-exist with 2G, 3G, and 4G mobile networks. Today, cellular gateways are frequently used to aggregate data from many sensors and send that information to the server. NB-IoT devices, however, can send data directly, eliminating the need for a cellular gateway and the costs associated with it.

However, whilst NB-IoT can work well in the right use cases, it has lots of limitations. These limitations can be quite restrictive meaning that often other options such as LTE-M may be better fit, providing similar benefits but with greater flexibility…choose carefully!

The benefits of NB-IoT

  • Lower device manufacturing costs: NB-IoT protocols feature much simpler construction. Using chipsets specifically engineered for them reduces the connectivity component cost, which lowers the cost of the overall device.
  • Power efficiency: Due to its simpler waveform and the fact that the device disconnects when not collecting and sending data, battery lifetime expectancy can be as high as ten years.
  • Stronger coverage: Whether the device is used indoors or out, above ground or below, or deep within an urban environment, it should provide sufficient coverage—even when power sources are unavailable.
  • Security and reliability: Because it operates within a licensed spectrum, NB-IoT features guarantee quality of service which ensures reliability. It also benefits from the security features of mobile networks, including device identification, user privacy, authentication, and data integrity.
  • Scalability: Through its ability to support large numbers of devices over a wide geographic area, millions of devices could potentially connect via a single deployment.
  • Simple implementation: By installing on current networks and leveraging existing cellular infrastructures, NB-IoT integrates relatively easily into a mobile operator’s existing IoT platform.

The limitations of NB-IoT

  • Limited data transmission: NB-IoT is best suited to very low data applications, such as those use cases consuming less than 1KB per day. It will typically provide approximately 20Kbps upload speeds with a the theoretical peak upload of 66Kbps for slightly higher data applications with power constrained devices but this is still significantly lower than other technology choices. NB-IoT also has high latency performance, so is unsuitable for applications where latency is critical. These limitations mean it is important to think carefully about requirements before choosing NB-IoT
  • Limited device mobility: NB-IoT devices will remain connected only within a finite environment and only to a single network operator. This could mean limitations for uses like wearables that leave a designated perimeter. If the device enters another country, it’s at risk of becoming unusable if the operator has no local presence there. This may change in the future as the ability to remotely provision profiles OTA via NB-IoT becomes available but for now it is a limitation.
  • Data costs: Connectivity costs are typically higher than 2G/3G/LTE CAT1 pricing, placing additional limitations on the use of the device.

There are several alternatives that may be better suited to provide the functionality required for your device’s specific use cases. Among the most common is LTE-M.

What about LTE-M (CAT-M)?

LTE-M is an alternative LPWAN technology also built to support a longer device lifespan. As with NB-IoT, by allowing the device to sleep when not in use, its battery can last for years. LTE-M can co-exist with 2G, 3G, and 4G and also deliver the benefits of mobile networks—mainly security and privacy features.

However, because LTE-M is compatible with the existing LTE network and uses existing LTE base stations, device mobility isn’t a problem. This could make it much better suited for some applications.

Unlike NB-IoT, LTE-M also allows for significantly higher data rates, which is important for more data-rich use cases. And bandwidth optimizations can be used to achieve the same in-building and rural coverage as NB-IoT. LTE Network compatibility also means new antennas aren’t required—carriers simply need to upload new software.

Overall, LTE-M provides more flexibility and scope whilst still being able to offer many of the benefits of NB-IoT.

When is NB-IoT the right choice?

Each IoT device has its own unique set of requirements. The connectivity option that’s perfect for one may be entirely wrong for another. The good news is, there are many to choose from. The first step is to ensure you have a thorough understanding of your requirements. NB-IoT might be a good option if your device:

  • Is likely to be placed in remote, underground or hard-to-access locations.
  • Remains stationary.
  • Does not require the high-bandwidth necessary to transfer large amounts of data, including large files, voice or video.
  • Requires very long battery life.

While NarrowBand Internet of Things (NB-IoT) has been attracting a lot of hype as the leader in next-gen IoT connectivity and certainly has a lot of benefits, it is not the only option. There are several alternatives that might be better suited to your project including LTE-M and choosing the best one for your specific requirements can be tricky. If you need a little more information, we have written an overview of the other connectivity technologies which covers not only CAT-M but also several other popular connectivity options.

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