But with M1 and NB1 standards, even bigger power savings come from “the deep sleep mode,” designed into the newly developed narrowband IoT specs, explained Karam.
Both M1 and NB1 protocols are designed to allow IoT devices to stay in deep sleep most of the time. They wake them only sparingly, like once a day or once in several days, rather than forcing them to frequently wake up to check network status.
It all depends on use cases
So, which IoT applications are best suited to M1 compared to NB1? How can IoT device developers make the most of the two specs?
It all depends on use cases, according to Karam.
As far as data rate is concerned, such applications as an IoT temperature sensor will require only the smallest amount of throughput – 10s of kbps — as available with Cat NB1. But a health or fitness wearable device, transmitting more data, will demand the higher throughput of Cat M1. At the 1Mbps throughput maximum enabled by M1, “you might even be able to add video on a small screen, or voice recognition features,” said Karam.
Connected mobility is determined by the ability of a technology to do handover between cells. Cat M1 supports handover, but Cat NB1 does not. “If your application is mobile, such as a health or fitness band or other wearable, Cat M1 is needed,” according to Sequans. If the application is stationary, as in an industrial sensor, then Cat NB1 will do.
Things get trickier, and consideration of use cases becomes critical, with power consumption. NB1 does not necessarily promise lower consumption for all IoT devices, according to Karam.
For data transmissions above a certain level in hundreds of bytes, Cat NB1 will consume more power than Cat M1. “The higher Cat M1 throughput allows devices to get to sleep faster between transmissions, thus saving power,” Karam explained.
Hence, Cat NB1 is more suited for simple sensor and metering applications, transmitting in short bursts, but Cat M1 is preferable for applications needing to transmit more than a few hundred bytes of data, according to Sequans. Market size
According to ABI Research, cellular IoT connections will exceed 1 billion in the 2020/2021 timeframe with a large chunk of these connections from LTE Cat 1, Cat M1 and Cat M2 (NB-IoT).
Dan Shey, managing director and vice president at ABI Research, told us, “We believe that the standardization of LTE Cat M1 and Cat M2 and its adoption into various IoT use cases has added about 7% to the cellular IoT growth rate.”
IHS Markit has pegged the number of cellular IoT connections at year-end 2015 at 227.5 million. It expects an increase to 283.9 million this year.
However, as M1 and NB1 start to come online, IHS’ Lucero believes they “will make a much wider range of business cases accessible for direct cellular connectivity.” After all, it’s much better than having to work through low cost short range wireless technologies connected through a gateway, he said.
Next page: Windows for LoRa, Sigfox narrowing?