The Case For Narrowband-IoT

Cellular network-based Narrowband IoT (NB-IoT) is marching closer to reality as players across the ecosystem put forth silicon IP, software protocol stacks, carrier network software upgrades and more.

The kicker came last year when the 3rd Generation Partnership Project (3GPP), the global cellular industry standards body, finalized a NB-IoT standard in its ‘release 13.’ With that, device makers and carriers and all of the companies that support them had much less of a moving target in realizing IoT.

“NB-IoT is really the standard that has the greatest potential,” says Paul Williamson, general manager for ARM‘s wireless business. “With the support of the cell phone carriers, rollouts are starting this year for that technology.”

As hard as proponents of LoRa and Sigfox tried, the business case for these technologies to bring about the potential in IoT does not appear to be as strong as for NB-IoT. By utilizing the world’s existing cellular infrastructure, NB-IoT brings a more ‘guaranteed delivery’ capability. Similarly, the “personal area network” vision of IEEE 802.15.4, encompassing Zigbee and Thread, are more limited in comparison.

Fig. 1: Where NB-IoT fits. Source: Qualcomm.

“You already have the cell towers,” said Williamson. “You don’t have to build infrastructure to connect all of the devices.”

Ericsson AB is ready with the software, ’17A,’ which carriers can use to upgrade their existing LTE networks to work with any NB-IoT-enabled endpoint. Further proving the industry is putting some energy behind this, Huawei has an NB-IoT lab at Deutsche Telecom, and Vodafone has one in Barcelona.

“So at ARM we asked, ‘How do we enable the silicon vendors to be a part of this, to create end point devices?’ We know that certification to work on carrier networks is difficult and expensive,” said Williamson. “How do we make this technology more accessible to the market?”

The effort started about 18 months ago when ARM bought South Florida-based Sunrise Microdevices, bringing in its radio design team and expertise around Bluetooth Low Energy. Then a couple of weeks ago, ARM officially added Mistbase of Lund, Sweden, and NextG-Com of London to add RF and baseband hardware IP and the corresponding software layers 1, 2 and 3 that align to NB-IoT.

“We knew we needed a low-power, low-data rate standard. And Bluetooth Low Energy fits that bill from a data perspective, from a low power perspective,” said Williamson. “But it has a range limited, maybe at the very peak 100 meters. Yes, they are bringing in mesh technology to help that. But consider you have a controller on every street light in a city. To do that with Bluetooth LE you’d have to roll out access points [infrastructure equipment], even if there was meshing and connections between them. When you get a cellular WAN standard, your range is measured in kilometers.”

ARM is not the only semiconductor technology house looking to boost the NB-IoT market. Cadence is collaborating with Dresden, Germany-based CommSolid to offer the necessary device-level technologies.

CommSolid’s Matthias Weiss has spent years working towards this goal with a team of 30 engineers that once comprised an Intel LTE team. The first order of business has been driving device costs down via integration and by reducing complexity.

The team has integrated the power amplifier and SIM, and simplified the RF and front end module. The entire module now will have an ASP below $5. This should further what is seen as the main use case for NB-IoT: transportation, logistics and supply chain.

“Providing regular updates on the position, the state of the goods, or the delivery status allows companies to massively optimize their delivery process,” says Weiss. “They see a tremendous opportunity to reduce the costs associated with tracking and moving assets.”

The next 3GPP meeting is set for West Palm Beach, Fla., the week of June 5. Weiss says release 14 of NB-IoT will come at the next quarterly 3GPP meeting, in September. That release has additional features, including location without GPS, multicasting, and, crucially, ultra low power classes in the 14 decibel-milliWatts (dBm).

The overarching power goal has long been devices with no ground power that can last in the field for 10 years, according to Williamson and Weiss. It’s not simple to put that into power consumption terms, though.

“The battery life is really determined by the duty cycle,” says Weiss. “That is, the time the device is active to receive and transmit data vs. the time that the device is in sleep mode. Typically, [these devices] will have very short duty cycles. In other words, the devices will sleep for a long time.

“Devices in this mode should definitely be able to live in the field for 10 years,” says Weiss. “Counterintuitively, the IoT power problem is dominated really by solving the sleep mode power consumption issue.”

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