A compact module previewed in Norway promises to give small IoT devices the worldwide range and roaming capability of LTE-M cellular connectivity

By Richard Quinnell, editor-in-chief

For
IoT devices that remain fixed in place or are confined to relatively small
spaces, a local area network like Wi-Fi or ZigBee provides adequate
connectivity. But if the device needs to remain connected while roaming over
hill and dale, or even from continent to continent, there have been few good
choices. A compact system-in-package (SiP) from Nordic Semiconductor intends to
change that situation, however, by bringing multimode LTE-M NB-IoT cellular
connectivity to power-constrained IoT device designs.

Cellular
technology has become so pervasive that there are more active cellphones in the
world than there are people, and it has been this way for several years. So it’s only natural
that developers of IoT devices that need to operate within a large geographic
area have been looking at cellular as a wide-area connectivity option for some
time. But factors such as the power demands, size, and cost of cellular
transceivers have been an impediment to the implementation of cellular IoT.

The
nRF91 series modules recently demonstrated in Oslo
promise to change that and bring cellular data connectivity to the broad IoT
market. The SiP integrates a complete low-power cellular IoT system into a tiny
10 x 16 x 1.2-mm package that integrates modem, transceiver, RF front end,
dedicated application processor, Flash memory, power management, crystal, and
passive components while eliminating the need for surface acoustic wave (SAW)
filters for precision frequency selectivity.

Nordic-nRF91-low-power-cellular-IoT-SiP

The
module will come with complete regulatory and cellular certification, so
developers can essentially drop the module into their design and be confident
that it will meet government and service provider requirements for connecting
to regional networks almost anywhere in the world. A multi-mode design based on
Nordic’s SAW-less transceiver and a custom RF front end from Qorvo allows the
SiP to accommodate country-specific variations in wireless standards. The
demonstration, for instance, had the device working on the Verizon Wireless
network of the U.S. and the Telia network of Norway.

The
device’s processor is based on the ARM Cortex-M33 with TrustZone CryptoCell-310
security technology, providing developers with a powerful and secure platform
on which to run their application code. This will help to ensure that the user’s
data is kept secure and that the device hardware and code are hack-resistant.
It also helps eliminate the cost, power, and size penalties of a second
application processor; the ARM core is powerful enough to run both the
communications protocols and the user code.

Along
with its small size, the module promises low-power operation that maximizes
battery life. Power consumption and data rates are inversely related, but at
its maximum rate of 360 kbps, the device will consume only about 150 mA, the
company claimed in its “sneak-peek” presentation. It also
pointed out that the device, when transmitting data every 20 seconds, would run
on batteries for six months and could provide up to 15 years of battery life
when set to connect only every 10 minutes.

While the device is not yet generally available
for most IoT developers, it should be soon. Nordic has been delivering samples
to lead customers since December and expects to start general sampling by mid-2018.
Production quantities, with full production-ready software and certifications,
should be ready by the end of the year.