The 4G/5G boundary is about to become really fuzzy. Today, Qualcomm announced the X24, a 4G LTE modem that can reach 2Gbps, or about half the maximum speed of its current 5G modem—and faster than the average 5G customer will receive for years.
The X24 does this through 7x carrier aggregation, bonding seven different 20MHz slices of radio spectrum and enabling 20 data streams at once. That will rely not only on licensed spectrum, but on carriers using Wi-Fi airwaves to transmit LTE data, which is called Licensed Assisted Access or LAA.
“Not a lot of operators have seven carriers,” said Sherif Hanna, director of product marketing for modems at Qualcomm. “But what they do have is four or five, and now they can use those and add LAA as well on top of it.” T-Mobile and AT&T are both implementing LAA in the US, Hanna said.
The modem can also do 4×4 MIMO on five carriers, which would also achieve 20 data streams. Operators like Australia’s Telstra could do that, Hanna said.
The new modem follows the 1.2Gbps X20, which is the modem in the Samsung Galaxy S9’s Snapdragon 845 chipset. The X20 allows for 5x carrier aggregation and 12 streams of data. The announcement also beats Intel’s XMM7060 modem, scheduled for mid-2019, which will support 1.6Gbps.
The X24 will hit the market by the end of this year, when we’ll see the first 5G devices starting to hit as well. It’ll also probably be part of next year’s Snapdragon chipset, which would (in theory) feature in phones like the Samsung Galaxy S10, if that exists.
What’s 4G, What’s 5G?
In the first few years of the 5G changeover, we’re going to see up-to-2Gbps 4G; a low-to-mid-band nationwide mobile 5G, which T-Mobile and Sprint are setting up, which could be about the same speed; and a short-range, high-speed 5G being laid down in big cities.
The capability overlap between 4G and 5G here isn’t actually all that weird; it happened with 3G and 4G, too. Putting aside the non-speed-related aspects of 5G, the importance of the new technology is that it will be able to ramp up far higher than 4G ever would, not that it would start that way.
When we first got 4G in 2011, 5-10Mbps speeds were common on Verizon’s LTE network. (We tested and showed those results in our Fastest Mobile Networks 2011 feature.) But HSPA+ 42, a 3G system, was later able to catch up to those speeds. LTE now runs at speeds HSPA+ couldn’t even dream of, of course.
5G has advantages other than speed. The system will run with much lower latency than 4G, which means greater responsiveness, especially for applications like self-driving cars. It will also enable many more connections per cell, which is important for sensor networks. So there’s still reason to build 5G as 4G gets faster.
The first 5G networks will be “non-standalone,” which means they’ll be dependent on 4G connections to set up and run. The highest 5G speeds will also require millimeter-wave networks, which only cover short distances and so will initially be in dense city centers.
That means for a fully 5G-like experience, you’re going to need the X24’s variety of 4G, as well. X24-based phones that also have 5G modems will, ideally, smoothly ramp up and down between fast LTE and early 5G networks without experiencing the sort of “speed cliff” you feel when you drop from 4G LTE to EDGE, for instance.
“The plan for smartphones is that you’ll have an SOC with an integrated gigabit LTE modem, and the 5G subsystem which includes the 5G modem will exist alongside it on the board,” Hanna said. “I would say that’s in a 5-inch or 5.5-inch class device. The footprint of the chips is pretty small.”