If you want to get a sense of where cellular technology is headed, a good resource is the Ericsson Mobility Report, an annual publication that offers detailed analysis and projections for mobile networks. Their latest report, dated November 2019, has some interesting things to say about the internet of things (IoT).
Ericsson forecasts that by 2025 there will be nearly 25 billion IoT connections worldwide and 20% of them will use cellular connectivity. What’s more, while many of those cellular connections will continue use legacy networks (2G/3G), most newly connected devices will use LTE technology, in the form of LTE-M or NB-IoT.
That’s a big shift, given that 2G and 3G networks currently support nearly a billion connected devices.
So why, if 2G and 3G offer the kinds of low-power, low bandwidth operation that so many IoT deployments need, would deployments start migrating to something else? Widespread deployment of 4G LTE networks and the arrival of 5G have a lot to do with it.
Mobile network operators around the world are re-purposing their spectrum to make way for newer technologies. In most cases, operators are sunsetting 2G or 3G, but not both. From a worldwide perspective, 2G and 3G are both still operational, just not always in the same place.
In Asia, Oceania and North America, 2G is already gone, but 3G is still available. On the other hand, in Europe and Africa, 2G is likely to outlive 3G. That’s because in Europe, the prominence of the IoT means 2G is still lucrative, and in Africa, lack of 4G voice-over-LTE (VoLTE), along with 3G fallback to 2G, makes 2G a valuable asset for voice services. In Central and South America, it’s harder to generalize, since network operators are still evaluating their options.
Faced with this uncertainty over 2G and 3G coverage, many IoT developers have turned their attention to LTE-M and NB-IoT, two newer cellular technologies designed for IoT operation.
LTE-M and NB-IoT are both low power wide area (LPWA) technologies, designed for use in the IoT, which means they meet the essential IoT requirements of battery life, reliable coverage, high network capacity and low operating cost. As a general rule, LTE-M is the preferred option in Australia, Japan and North America, while NB-IoT is more popular in China, Europe and Russia.
LTE-M and NB-IoT consume very little power and offer battery life of 10 years of more. The main differences between the two are latency (the time it takes to get on a network and send a message) and speed (the amount of data transferred per second). NB-IoT, the slower of the two, is designed for things like static sensors, which have low data needs and don’t need to be connected all the time. NB-IoT uses batch communication to reduce power consumption and offers improvements in system capacity and spectrum efficiency.
LTE-M, which offers the highest bandwidth of any LPWA technology available today, exceeds the speed and latency of 2G but may not match 3G for speed. LTE-M supports real-time communication and is a good choice for fixed and mobile applications that benefit from lower latency and over-the-air updates.
LTE-M and NB-IoT can be used to replace 2G and 3G and also offer an easy roadmap to 5G LPWA as it becomes available. Today’s commercial versions of LTE-M and NB-IoT are forward-compatible to 5G, meaning they can operate within a 5G network. Also, many LTE-M and NB-IoT hardware modules are upgradeable to 5G LPWA with a simple over-the-air software upgrade, so in-place deployments can migrate to 5G without a truck roll. For deployments that have a global footprint, many 4G and 5G LPWA solutions also support fallback operation to 2G, so designs that use NB-IoT or LTE-M will work in areas where 2G is still available.
Cellular connectivity is, of course, just one part of an overall IoT design and only one of the considerations for developing a secure, battery-operated device. The MCU plays a key role in optimizing overall performance, giving developers options for fine-tuning power consumption and adding the security algorithms needed to protect data and the network.
At NXP, our microcontroller group has made it easier for developers to optimize and deliver cellular-enabled designs based on LTE-M and NB-IoT. We’ve partnered with Sequans, a leading provider of cellular modules for IoT devices, to bring LTE for IoT connectivity to our LPC5500 MCU ecosystem.
The LPC5500 series is specifically designed for low-cost, secure edge processing. Built on a low-power 40-nm embedded flash process, the LPC5500 series brings together new levels of functionality combining significant product architecture enhancements and greater integration over previous generations. Integrated security features include SRAM PUF-based root of trust and provisioning, real-time execution from encrypted images (internal flash) and asset protection with Arm® TrustZone®-M. These features address the ongoing need for protection in IoT environments that involve hundreds, if not thousands, of devices transmitting and receiving sensitive data over the network. The extensive developer ecosystem includes a comprehensive set of design tools that simplify development and enable strong security in end-node devices.
The LPC5500 now combines with the Sequans Monarch GM01Q (LTE-M/NB-IoT) and NB01Q (NB-IoT) modules to create a development platform that speeds time-to-market for cellular-connected IoT devices. Both Sequans modules support 17 LTE bands for worldwide connectivity and consume less than 1 µA of power.
The reference design software is completely open source and scheduled for mass production this summer. It will be available through Avnet and Element 14 for $99 USD MSRP. The partnership with Avnet has enabled us to rapidly extend the capabilities of the reference design and provides a worldwide supply and support channel for NXP and Sequans. The reference design promises to accelerate connecting an IoT node to various cloud solutions such as Amazon AWS and Microsoft Azure in a secure way. Additionally, the reference design shows a customer precisely how to configure both the GM01Q and LC5500 to operate together in a low-duty cycle ultra-low power application to maximize battery life.
The NXP/Sequans combination creates an ideal platform for product evaluation and prototyping, with an emphasis on secure, low-cost edge processing.