AT&T launches narrowband IoT (NB-IoT) as complement to LTE-M for Internet of Things connectivity

AT&T recently launched narrowband IoT (NB-IoT) service to support the simplest sensors—typically using little bandwidth and power—with potential price targets of $5 per NB-IoT module and data plans of $5 per year, according to a company official.

Internet of Things (IoT) pundits have long projected that billions of devices would be connected to fuel an explosion of data that is expected to fuel efficiencies in myriad ways, including smart-cities, smart-grid, smart-manufacturing and smart-farming initiatives. While high-bandwidth applications like video-surveillance can be part of these initiatives, most IoT sensors can be fairly straightforward and ideally would require few resources to install and maintain.

Although “narrowband” is part of the NB-IoT moniker, it is different from the narrowband reference in the LMR arena, where channel widths typically are 25 kHz, 12.5 kHz or 6.25 kHz. Operating on 200 kHz channels, NB-IoT can deliver 64 KB/s data speeds, while LTE-M on 1.4 MHz channels supports throughput of 384 KB/s, according to David Allen, director of IoT advanced product development for AT&T.

“Narrowband IoT is similar to LTE-M, in that they’re both complementary to each other, they’re both defined in the 3GPP standards body for wireless networks,” Allen said during an interview with IWCE’s Urgent Communications. “We think of LTE-M for things like your alarm panels in your home and smart goods, like connecting your smart refrigerator. It may require a little more bandwidth, and it may support voice services—for instance, your alarm panel may support voice—so that’s what LTE-M gives you.

“Narrowband [IoT] is really used for little, simple sensors. They’re going to be asleep most of the time, and when they do send data, they’re going to chirp a little bit of data—maybe just an on/off-type toggle that says, ‘I’ve triggered’ when detecting [an event].”

Event detection can include a variety of use cases, such as water detection or when a typically locked door is opened, Allen said. Globally, NB-IoT already is being used in smart-metering and smart-parking applications, as well as monitoring the status of often-overlooked infrastructure.

“You have these big manhole covers that are sitting in the middle of sidewalks or streets,” Allen said. “What you don’t want to have happen is, you don’t want those things to disappear on you, because then it’s a hazard. In other parts of the world, you see narrowband IoT being used for those specific smart-city applications.”

Some IoT solutions exist today in the U.S., but they often require considerable work by the customer to deploy them, including pairing the device with a Wi-Fi system and then provisioning access through an enterprise firewall that is designed to bolster security—a cumbersome process that “really kills the adoption rate,” Allen said.

In contrast, AT&T’s NB-IoT service is designed to be deployed quickly, in part because it uses the AT&T wireless network as backhaul, according to Allen.

“You just plug it in, and it starts communicating with our cellular network,” he said. “It’s already been provisioned and it’s already communicating to the network, so you don’t have to—as a consumer—go through those steps to try to find your Wi-Fi system. That’s what we mean by ‘it works out of the box.’”

Leveraging AT&T’s commercial wireless network also helps NB-IoT customers address one of biggest concerns associated with IoT deployments: security.

“Much like in the cellular world, it’s a multilayered approach,” Allen said. “It uses a SIM within the device itself. The SIM is your authentication that your account is yours, and it’s communicated through an encrypted air interface. Then, it’s communicating through a custom virtual private network that’s been established with a white-goods manufacturer or with an insurance company, whoever is providing that service.

“It’s all done over licensed spectrum—the spectrum that AT&T owns and nobody else can use—versus Wi-Fi, which is accessible by anybody and can be interfered with by baby monitors, cordless telephones and things like that.”

Of course, if leveraging the AT&T network required the $40-plus per month per IoT device that is charged to LTE smartphone users, widespread deployment of IoT devices would not be practical, in many cases.

“We’re working with module vendors to come up with a $5 module—that’s unheard of historically in the cellular world,” Allen said. “If you think of traditional LTE, the best price point is a $14.99 module, so this is one-third of that price.

“Then, if you look at the data plans … we’re talking about $5 for a year’s worth of data. Those are the new price points that can really make water-leak detectors and smart appliances useable and economical to deploy now.”

Allen noted that NB-IoT and LTE-M are both designed for use cases that are considered to be “latency tolerant,” because it is possible that the device may have to send its signal multiple times before it is received. Latency-sensitive IoT applications should use more robust connectivity than is provided by NB-IoT or LTE-M.

In addition to its other attributes, NB-IoT devices are designed to be power efficient, so they don’t have be replaced often—for years, in many circumstances, Allen said.

“Your cell phone effectively stays attached to the network all of the time,” he said. “It’s sending little bits of data, because you probably have some apps on your phone that are helping you monitor your health, check your e-mails and those types of things, so you’re in a continuous type of connection with the network.

“With these data plans for LTE-M and narrowband IoT, the traditional use case is that you’re going to put the device to sleep. [The IoT device is] going to transmit some data, listen to see if the application wants to send data down to the device, and then it’s going to go to sleep for awhile. It will wake back up if it detects water or because it has to do a daily report of the flow usage off a water meter … We’re expecting [the IoT device] to wake up, transmit data, and go back to sleep.”