ULP Wireless Update

The promise of low power cellular IoT

The promise of low power cellular IoT

A major advantage of low power cellular IoT is that the supporting infrastructure is already in place even in remote areas of the globe

The latest LTE standard includes a specification for low power cellular technology which will accelerate development of the IoT

Long Term Evolution (LTE) is a standards-driven technology for high-speed cellular connectivity, designed to provide high- bandwidth communication for mobile devices.


The LTE standard is managed by the 3rd Generation Partnership Project (or 3GPP, comprising a collaboration between telecoms partners) and was first specified in the organization’s Release 8 document with enhancements added in Release 9. Since then, LTE has been adopted by most of the international cellular service providers (‘carriers’) including those in North and South America, Europe, Russia, India, China, Korea, and Australia. The standard covers a number of frequency bands in the 700 to 2600 MHz range to facilitate its use by carriers in different regions.


Internet access using a cellphone connected via LTE is something consumers take for granted. It’s a simple step, therefore, to imagine a world where the emerging Internet of Things (IoT) also leverages such technology to connect billions of sensors to an expanding network. It’s a much harder step to make it happen. But now, 3GPP is tackling the challenge head-on by introducing enhancements to the LTE specification that will allow pioneering companies such as Nordic Semiconductor to come up with practical ‘low power cellular IoT’ solutions.


From LAN to WAN

Today it’s relatively simple—courtesy of technology developed by companies like Nordic—to connect a Bluetooth low energy-powered sensor to the IoT, provided a smartphone or Wi-Fi router is available to act as a ‘gateway’ to the network. Such Local Area Networks (LANs) are commonplace in homes and offices. But for the enterprise, industrial, and agricultural sectors among others, things can be more of a challenge because in many applications the sensors—particularly if they are attached to an object that’s on the move—could be out of range of a LAN.


Cellular technology is a proven way to directly connect remote devices to the Internet in the absence of a LAN, and a healthy industry has grown supplying modules using 2G and 3G technology for Wide Area Network (WAN) applications such as Machine-to-Machine (M2M) communications.


Unfortunately, the modules are expensive ($30 to $40 for 3G devices), bulky, and consume lots of power so are poorly suited to multi-billion installation applications such as sensors used for parcel tracking. As a result, there’s increasing demand across a broad market for low-cost (sub-$5), compact, microampere LTE modules that support ‘Low Power WANs’ (LPWANs).


Further, carriers are keen to encourage low-power, low-data rate devices because they have the bandwidth to accommodate extra data alongside the high-demand traffic transported over their networks. Such business promises to provide a welcome new revenue stream to offset the huge costs incurred by the carriers when buying parts of the radio spectrum.


To meet this groundswell, 3GPP has introduced a specification for two forms of low power LTE— LTE-M (for M2M) and Narrow Band-IoT (NB-IoT)—detailed in Release 13 of the standard. LTE-M specifies a low-complexity modem enabling simpler, reduced cost, and lower power LTE devices to be developed with peak uplink and downlink data rates of approximately 300 kbps, RF bandwidth support of 1.08 MHz, and 20 to 23 dBm transmit power.


NB-IoT features an RF bandwidth of 180 kHz with peak data rates of approximately 30 kbps. Transmit power remains at 20/23 dBm. Both LTE-M and NB-IoT devices will have a range of tens of kilometers and battery life of at least several years.


There are competing technologies, but a major advantage of LTE-M and NB-IoT is that the supporting infrastructure is already in place across the majority of the globe. In contrast, competing technologies are faced with billion-dollar, multi-year building programs to assemble equivalent infrastructure.


From specification to commercial product is a long road. Some companies have announced products for volume production in 2017 to coincide with first commercial deployments of the enhanced cellular infrastructure required to support low power cellular IoT. Broad coverage of this infrastructure will occur between 2017 and 2020. Nordic is planning its product introduction to coincide with this schedule.


But perhaps more significantly, only a handful of companies have the engineering capability to design LTE wireless (which is a complex technology) and even fewer have the complementary expertise needed to develop low power cellular IoT devices.


Nordic is one of those companies. Not only does the company have over a decade of leadership in ultra low power wireless—culminating in the company’s latest class-leading nRF52 Series Bluetooth low energy SoCs—but it also has an engineering team in Finland comprising several of the engineers that were responsible for many of the inventions that underpin LTE technology.


It’s an exciting combination of skills and the engineers are working on the products outlined in Nordic’s roadmap for the nRF91 Series low power cellular IoT solutions. These products will meet the demands of the rapidly evolving IoT landscape. It’s a landscape that will look very different in just a few years time.