While most people dream of ever faster LTE, a dedicated band of innovators is striving to make the latest and greatest cellular system more like 2G.
That’s the goal of companies working on special versions of LTE that run slower but are cheaper and use up less space and power. Those advantages are tailor made for the Internet of Things, but other kinds of networks offer similar benefits.
Next week at CTIA Super Mobility Week in Las Vegas, communications chip maker Sequans will join with network giant Ericsson to demonstrate LTE Category 0, a variant of the global cell standard that Sequans expects to hit the market next year. It could go into connected devices like parking meters, credit-card terminals, oil tank sensors and even wearables. Meanwhile, another form of low-power LTE called Category 1 should ship in devices starting in the next couple of weeks, according to Sequans. On Monday, cellular vendor Gemalto announced a Category 1 module for mobile devices that Sequans says is built around its chip.
Carriers started activating LTE around 2010 to give subscribers faster data connections and carry the growing traffic on their networks more efficiently. They did it with the fastest type of LTE, called Category 3, which had a theoretical top speed of 100M bps (bits per second) under perfect conditions. But the same 3GPP standard that defined that system also included LTE Category 1, with a top speed of 10Mbps and the capability to run on less power.
Most IoT devices are smaller than smartphones or tablets, and some need to keep working for years in hard-to-reach spots where their batteries can’t easily be replaced. The type of LTE that lets your phone connect to the network at tens of megabits per second consumes too much energy for those batteries to stay alive. But IoT devices don’t need that much speed, either, and that’s where Category 1 and Category 0 come in.
Category 1 sat unused for a few years as machine-to-machine communications used the slow but cheap 2G and 3G networks that lived alongside LTE. Now carriers are taking steps to dismantle those networks, starting by reusing some of their frequencies for LTE.
Meanwhile, the number of new IoT devices is quickly growing. To stay connected for the long haul, those endpoints will have to be equipped with LTE, which is expected to remain in place for many years.
Category 0 will take the trend another step further, with a target speed of 1Mbps both upstream and downstream. Whereas Category 1 is about 30 percent cheaper and more power-efficient than regular LTE, Category 0 will probably cut another 30 percent from that, said Craig Miller, vice president of engineering at Sequans. Major changes in Category 0 will include eliminating the requirement for two antennas and for sending and receiving data at the same time, he said.
After Category 0, the 3GPP is expected to craft yet another system with even lower speed and power needs.
There’s a place for low-power networks like these, but their success isn’t guaranteed.
There are other low-power, wide area technologies already on the market, like the system that’s been deployed in several countries by French network vendor Sigfox. To truly become cheap, a technology has to reach large scale, and neither of LTE’s special IoT categories has proved itself as a big hit yet, said analyst Peter Jarich of Current Analysis. They will need to hold their own against the alternatives.
Also, the string of technologies coming from the LTE industry could compete against each other as vendors and carriers wonder whether to adopt one or wait for the next. And looming over those decisions is the prospect of 5G, which is expected in 2020 and will have its own provisions for IoT.
The LTE industry may need a consensus on timing that it hasn’t yet reached, Jarich said. “Someone needs to make that gutsy decision.”