Cellular Puts IoT on Speed Dial

　　Carriers are driving aggressively into cellular IoT, with China Telecom leading the way with narrowband IoT (NB-IoT). They are playing a game of catch-up that some expect they will win with low-power wide-area (LPWA) alternatives led by Sigfox and LoRa that had a two-year-plus head start.

　　That was the picture from the Mobile World Congress Americas, where each side made the case for its play in the emerging Internet of Things. “It feels like we are on the cusp of an IoT explosion,” said Karri Kuoppamaki, vice president of technology development and strategy at T-Mobile, which aims to roll out an NB-IoT network in the U.S. by June.

　　“What’s next and key is showing an ROI in real networks,” said Hardy Schmidbauer, chief executive of TrackNet, a startup launched this year using LoRa and Wi-Fi for asset tracking.

　　“Carriers would like to wipe out their LPWA competitors, and I believe they will,” said Michael Murphy, CTO in North America for Nokia. “There is zero doubt [that] carriers view this as one of their most important goals.”

　　China Telecom appears to be in the lead with millions of users on a national network that it switched on in June for NB-IoT that supports 20- to 60-Kbit/s data rates over 200-KHz channels. The carrier charges as little as $3 a year for data, and its hardware suppliers such as Huawei and ZTE say that they soon will be able to deliver NB-IoT modules for less than US$5, said Qi Bi, chief technical officer for China Telecom.

　　“We ran out of devices; people are lined up … I think NB-IoT will take off big time in China,” he said.

　　China Telecom was surprised by two early adopters — bike-sharing companies such as Mobike and companies monitoring rented washers and dryers in apartment complexes. “We thought our major app was meters, but bikes became one of our biggest customers,” he said. “The IoT space is full of adventures and surprises.”

　　China Telecom also supports LTE-M, which supports data rates up to 1 Mbit/s but is less efficient, using about 1.4-MHz channels. LTE-M will mainly serve wearables and will likely cannibalize smartphone revenues, he said.

　　The carrier has seen its average revenue per user stay flat from 2G to LTE generations. It hopes that NB-IoT breaks with past trends, opening up new revenue streams by offering “better battery life, lower cost and better coverage” than LTE-M, he added.

　　T-Mobile hopes to follow in China Telecom’s footsteps, rolling out a U.S. NB-IoT net by June 2018. “China’s plan to go big on NB-IoT will give a boost to the ecosystem” said Kuoppamaki. T-Mobile will use its 600-MHz band, which “has very good propagation characteristics for most apps” ranging from asset tracking, smart lighting, and flood monitoring to tracking pets and clothes.

　　Like China Telecom, T-Mobile also will support LTE-M for “selected use cases, but NB-IoT has the most potential and verticals we talk to see it the same way; there seems to be pent-up demand in the space,” he added, noting that few apps need LTE-M’s support for voice.

　　In the U.S., AT&T was the first carrier to switch on an LTE-M network, leveraging the fact that it’s a software upgrade while NB-IoT requires new servers for some networks. AT&T says that its LTE-M modules are available for as little as $7.50, data plans start at $1.50/month, and starter kits with modules, software, and cloud storage are available on Amazon for $99.

　　While it monitors NB-IoT, “the cost has not been a big delta between the two technologies, and most of the apps are being served well with LTE-M for us,” said Mike Troiano, an AT&T vice president focused on the industrial IoT. Likewise, “in power consumption, there’s arguably not that much difference,” he said, expressing confidence that LTE-M could support a 5- to 10-year battery life for many nodes.

　　The carrier is supporting the varied business models for IoT. It estimates data use so that OEMs can bundle multi-year data plans into the costs of their products, and it can enable a SIM card in a car to split bills, charging the carmaker for emergency calls and the driver for hot-spot use.

　　Like other providers, AT&T sees asset tracking as a big but varied market, It includes users such as Otis elevators, McPherson Oil storage tanks, and GE smart streetlights.

　　3GPP defined both LTE-M and NB-IoT as part of its Release 13. They are expected to deliver two generations of annual upgrades before still-undefined 5G IoT specs get written. The Release 14/15 specs are expected to support mesh networking, better location tracking, and possibly range extensions.

　　NB-IoT is “already almost as well optimized as possible for LTE. There will be other flavors coming between LTE-M and Category-1 LTE, but our next focus will be on 5G IoT to make smaller, more power-efficient devices, possibly with better coverage,” said Kuoppamaki.

　　The LPWA space is likely to fragment over the next few years with all players getting significant slices of the pie, especially to early movers in unlicensed 800- to 900-MHz bands Sigfox and LoRa. Sigfox is expected to take the biggest slice, followed by NB-IoT and LoRA with LTE-M a distant fourth, according to a forecast from IHS Markit.

　　The Sigfox service aims at a broad bottom of an IoT pyramid. It supports the lowest data rates — just a few short, infrequent messages. Modules cost $2 and data rates start at $1/year in the U.S. and half that in Europe.

　　“It can cost up to US$10 to $12 a year if you have a lot of data, but few users ever get there … you need something below 3GPP, which will never get cheap, battery-efficient, and simple enough for things with a tiny bit of data,” said Allen Proithis, president of Sigfox in North America.

　　Like its rivals, Sigfox is not reporting the current number of its subscribers, but it claims use in Texas oil fields, large farms, and city water systems in San Francisco. It has networks running in 32 countries and an addressable market of 600 million people.

　　Sigfox sees itself as a network technology provider, generally working with partners that develop and deploy the final bits of software needed to create an IoT service. “Just in the U.S., there’s a half-dozen asset-tracking devices because everybody wants a slightly different mix of sensors,” said Proithis.

　　To date, Sigfox hasn’t made many inroads with cellular operators beyond a deal with KDDI in Japan and one with T-Mobile limited to “a market or two, but you will hear about some more because operators want to be a one-stop shop,” he said.

　　Its closest rival, the LoRa Alliance, has struck deals with more than 40 network operators, including Orange in France and Comcast in Europe. Rather than selling services, the alliance offers an open spec that anyone can adopt for public or private networks and has attracted more than 500 members and 350 trials to date.

　　LoRa’s asynchronous, spread-spectrum network enhances range and minimizes interference, said Schmidbauer, who was an early representative for LoRa when it was first rolled out by chip maker Semtech. Synchronous cellular IoT nets drain too much power to run nodes for five years or more on the kinds of sub-2,000-mAh, 3.6-V batteries [that] LoRa devices use, he said.

　　The unlicensed options are “not competing with NB-IoT. That’s like comparing Bluetooth and RFID — they are different apps and the overlap is quite small.”