As part of its run-up to nationwide 5G communications, T-Mobile has launched narrowband IoT, a series of bands intended specifically for sensors and other devices that communicate only small amounts of data at any one time, but which need a dedicated band in which to do it. To do this, T-Mobile has utilized the guard bands, which are narrow slices of frequencies next to their LTE bands used for cellular communications, as a way to achieve spectrum efficiency.
“Sensors don’t need to communicate that often and they only transmit a few bytes at a time,” said Balaji Sridharan, T-Mobile’s vice president of IoT (internet of things) and M2M (machine to machine). He said Qualcomm and others are already making the modems, modules and chips for narrowband IoT (NB IoT), and device makers are starting the process of getting them certified by the Federal Communications Commission. The IoT communications take place in the guard bands of LTE bands 2,4 and 12, which are already in use by T-Mobile.
The bandwidth devoted to IoT communications is about 200KHz, which is a tiny fraction of the bandwidth used by a cellular device. But because it’s devoted to IoT, the devices can use low power and low data rates, which means their batteries can last for years. Sridharan said he expects most of the use on these bands to be things like environmental sensors and asset tracking devices, although there is a vast number of types of devices that could use the T-Mobile network.
One type of device that won’t be on the IoT network is video. Sridharan said the bandwidth requirements for video are too high, and while there have been attempts to send compressed video using NB IoT, they weren’t commercially successful.
However, he expects significant success for devices that are well-suited for the IoT network. “You’re talking in the billions of connections,” Sridharan said. “Essentially what narrowband allows you to do is connect every single device out there.”
While the network is already up and running, currently there are very few devices able to take advantage of it. Sridharan said that will change in the next few months as devices are approved for use and then they’re incorporated into devices. Those devices are being made by Nokia and Ericsson, as well as by Qualcomm.
The T-Mobile action to go live with narrowband IoT happened less than a year after the company announced its intent last fall. Its first commercial test took place in January, and it was operational nationwide in July. Sridharan said one reason T-Mobile could provision its IoT network so quickly is because it simply required a software update to all of its cells. The infrastructure was already in place.
T-Mobile expects its NB IoT network to get a major share of device traffic for two reasons. First, it’s already running and device makers are already building products to run on the T-Mobile network, so when they’re needed, the network is there to work with them. The second reason is cost. T-Mobile’s current price for access to the IoT network is $6.00 per year. By comparison, Verizon’s plans are to charge about 10 times that much for its Cat-M devices. The T-Mobile price covers 12 megabytes per year.
While device makers are still in the process of gaining FCC certification, T-Mobile said in a prepared statement that “several NB-IoT modules based on Qualcomm’s MDM9206 LTE IoT modem are certified for use on T-Mobile’s network.”
The NB IoT field isn’t T-Mobile’s alone. AT&T is already working on provisioning its network for narrowband, but that move is still about six months from happening. Verizon hasn’t said when it plans to release narrowband communications for its network, although there’s speculation that it will happen in 2019.
However, there’s already being work done with T-Mobile’s IoT network. San Mateo County, Calif., has just opened an innovation center with T-Mobile’s NB IoT as one of the launch projects. The county plans to use the IoT network along with products and services from other vendors in a range of research activities that should eventually become ongoing activities. Those projects include environmental monitoring, water management, asset tracking, predictive waste collection and even parking management.
“It goes back to the commercial promise we made where you’re able to connect billions of devices,” said Sridharan. “This is the way we’re going to do it.”
“It’s very secure,” he added, “and it actually provides a great tool to lower the bar for experimentation. We’re working to get this in to the hands of the developer community.”
Getting the developer community on board would be a big help for T-Mobile, but the fact that they’re first by many months and cheaper by a lot when the whole thing gets started may make the most difference.