OnQ Blog

Snapdragon 820 countdown: breakthrough LTE and Wi-Fi with X12 LTE modem

15 Sep 2015

Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.

Over the past several weeks, we have been revealing details about the incredible features of the Qualcomm Snapdragon 820 processor. And today we are revealing the final piece of the puzzle.

The Snapdragon 820 is the most powerful mobile processor we’ve ever made. So it only made sense that we would give it the most advanced modem we’ve ever designed. Qualcomm Technologies is proud to announce that the Snapdragon 820 will feature breakthrough LTE and Wi-Fi technologies, made possible by an integrated, and newly upgraded, X12 LTE modem.

There are many superlatives I could use to describe the capabilities of X12 LTE. But I will choose just one: unprecedented. The list of breakthrough features is long and distinguished, but here are a few. On compatible networks, the Snapdragon 820 with X12 LTE is the first commercially announced mobile processor to support:

  • LTE Category 12 download speeds of up to 600 Mbps. Yes, 600 Mbps — as in “we just passed the half-a-gigabit mark.” That’s a full 33 percent faster than the peak download speeds of the X10 LTE modem in the Snapdragon 810, which supported up to Cat 9 (450 Mbps). Why? Because you’ve got big files to download from cloud storage, an Instagram feed to peruse, and high resolution videos to stream. And we want to help you do it all faster and smoother.
  • LTE Category 13 uplink speeds of up to 150 Mbps. That’s triple the peak upload speeds supported by X10 LTE in the Snapdragon 810. Triple. Why? Because Snapdragon 820 is designed to help you take amazing pictures and videos, and we want to help you share them even faster with your friends and family. And because you need high uplink bandwidth to look your best in your next Periscope broadcast.
  • LTE in Unlicensed (LTE-U). This one is a really big deal. Huge actually. More on that later.

Snapdragon 820 sneak peek

How about we give you a sneak peek of real, working Snapdragon 820 silicon? Here’s a video of it achieving LTE Cat 12/13 speeds in the lab, on a prototype device:

How does X12 LTE achieve those speeds? In the downlink (from the cell tower to the phone), it can bond together three LTE connections using LTE Advanced carrier aggregation and treat them like one much faster connection. In the uplink, the phone can send data to the tower on two LTE connections simultaneously, again using carrier aggregation.

Plus—and this is new—the X12 LTE modem supports “higher order modulation” on both the uplink and the downlink to achieve even higher speeds than would be possible with carrier aggregation alone. If you want to learn how that works, please see the “Appendix for Nerds” at the end of this post.

It doesn’t just stop at super-fast LTE. If you think you know how fast Wi-Fi can be, Snapdragon 820 is here to defy your expectations. With support for 802.11ac 2x2 MU-MIMO, which fundamentally changes how Wi-Fi works, Snapdragon 820 can support Wi-Fi speeds that are two-to-three times faster in crowded areas like airports, offices, or even your home (think about how many smartphones, tablets, and streaming boxes compete for bandwidth every night in your home).

Snapdragon 820 even supports the latest flavor of Wi-Fi—802.11ad—which supports multi-gigabit speeds. Just image what you can do with those kinds of speeds: multiple 4K Ultra HD video streams; lossless, instantaneous screen mirroring to your TV; the pure joy of backing up your smartphone’s entire camera roll to your network drive in mere seconds. With Snapdragon 820, I say, “all of the above.”

But wait, there’s more!

Why are LTE and Wi-Fi spoken of separately? They really shouldn’t be. We think bringing them together just makes so much sense. And that’s what we’ve engineered the X12 LTE to do.

For starters, the X12 LTE modem is designed to choose automatically between LTE and Wi-Fi, depending on signal quality, end-to-end speed, and Internet reachability. (Again, consult the “Appendix for Nerds” at the end if you want to know how it all works).

These smarts to choose between LTE and Wi-Fi really come in handy with Wi-Fi calling. Where the X10 LTE in Snapdragon 810 checked only for Wi-Fi signal strength before switching, the X12 LTE is engineered to first check all the factors listed above, to make sure that you’ll have a clear, high quality call over Wi-Fi. And if things deteriorate (for example, if congestion reduces speed on a public Wi-Fi hotspot), it’s engineered to switch your call back to the safety of LTE—all without dropping the call. Brilliant.

By the way, not only does the X12 LTE modem support HD Voice calls over LTE and Wi-Fi, it even supports native HD Video calls. So you can pick up the phone, dial your friend’s number, and have a video call instead of just voice—no extra apps needed. Awesome.

Wi-Fi calling is one example of bringing together not just LTE and Wi-Fi, but also bringing together licensed and unlicensed spectrum, the two types of airwaves that make all these amazing wireless technologies possible. But you know what? It’s time to bring those two much closer together—with LTE in unlicensed, a.k.a. LTE-U. It represents a fundamental shift in how mobile networks are deployed.

LTE-U timeline

Qualcomm Technologies first introduced the concept of LTE-U back in late 2013, and we’ve been working hard at taking it from a concept, to prototyping in the lab, and now bringing it to the real world.

LTE-U will allow operators to deploy small, compact cell towers called “small cells” (similar in size to a Wi-Fi router) in areas with a lot of demand for LTE data, for example in an airport, a mall, or at a crowded city street corner. When in range of those LTE-U small cells, phones using Snapdragon 820 with X12 LTE processors will be able to connect using at least two LTE connections: one in the operator’s regular licensed spectrum, and a new LTE connection in unlicensed spectrum. The two connections are bonded together using carrier aggregation to act like a bigger, faster connection.

If you’re the proud owner of a new phone powered by the Snapdragon 820, expected in the first half of 2016, and you’re on a network that supports LTE-U, you may experience a sudden boost in LTE speeds in areas that normally suffer from congestion. Not only would that let you get stuff done faster (like downloading that game at the airport before getting on the plane), and confirm that you made the right decision by investing in a phone with Snapdragon 820 (we applaud you), but you’d actually be making things better for all the other users within your vicinity as well. Why? Because LTE-U just allowed you to finish your download way faster, and now the network can turn its attention to serve the other users who were in queue behind you. Well done you.

Now you may be asking, “I know Wi-Fi uses unlicensed spectrum. Should I be worried about how LTE-U will affect my Wi-Fi?” From the very start, Qualcomm Technologies designed LTE-U to co-exist and share unlicensed spectrum fairly with Wi-Fi. You have to remember that Qualcomm Technologies is a leader not just in LTE, but in Wi-Fi as well. We understand the technology deeply. So we took special care while designing and implementing LTE-U to really, really make sure that it will have no more of an impact on Wi-Fi than deploying a normal Wi-Fi access point. You can read how we debunked that LTE-U myth, and others.

How about a demo though?

Great idea. You’re among the first in the world to see real X12 LTE silicon showing off its LTE-U chops on camera. And the best part? The video will show you just how well LTE-U and Wi-Fi work in the presence of each other. 

While it may be surprising at first, the results in the video are clear. Wi-Fi Network 1 speeds actually increased in the presence of LTE-U, over when it was trying to share with Wi-Fi Network 2. So LTE-U made things better, not worse. 

So get ready

Snapdragon 820 with X12 LTE is coming, and we’re expecting it to be amazing. This is the most advanced modem technology we’ve ever created: support for cutting-edge LTE-U technology, smart Wi-Fi calling, the fastest Wi-Fi technologies available, and exhilarating LTE speeds, plus way more (I would write about them, but they involve terms like 4x4 MIMO and uplink data compression, and my editor won’t let me. Just kidding—sort of.)

We’re so excited about how Snapdragon 820 is shaping up (if you couldn’t tell). Now you have a full picture of all its incredible capabilities, and we hope you’re as excited as we are.

Appendix for nerds

  • How carrier aggregation increases your LTE speeds

I had written this post on The Verge Forums a few months ago – it’s a good refresher on how carrier aggregation (CA) works its magic to increase network capacity and give you (and others) faster LTE speeds.

  • Higher order modulation

Think of the way that the cell tower and phone communicate as, in essence, an alphabet made up of a set of characters or symbols—except instead of being written in ink on paper, these symbols are written in electromagnetic energy and carried by radio waves. Up until now, the tower was limited to using a 64-symbol alphabet when it sent information to the phone (like when you’re streaming a video). In the other direction (like when you’re uploading a picture), the phone was limited to using a 16-symbol alphabet.

But that changes with X12 LTE. It is able to understand a much more complex alphabet made up of 256 symbols. Every symbol that the tower sends over the air carries 8 bits (1s and 0s) of information, as opposed to 6 bits of information previously. That’s how you get a 33 percent improvement.

Likewise in uplink, X12 LTE is able to use a 64-symbol alphabet, so that every transmission it sends to the tower carries 6 bits of information instead of 4. And that’s how you get 50 percent faster speeds. In pure geek speak, we’re talking about support for 256-QAM (quadrature amplitude modulation) and 64-QAM for download and upload respectively

Without higher order modulation, using 3xCA in the downlink and 2xCA in the uplink, we would be limited to peak speeds of 450 Mbps and 100 Mbps respectively. But turn on higher order modulation, and boom—we go to 600 Mbps and 150 Mbps peak speeds instead.

Here’s the catch (there’s always a catch in engineering-- always). Those new alphabets with additional symbols are much more complex. It’s really hard for the modem in the phone or the tower to tell all the symbols apart, because they all look so similar. Things get worse when you’re far away from the tower.

The symbols may not come through clearly enough for them to be distinguishable. So use of higher order modulation is possible in good signal conditions. That means if you’ve got a device with Snapdragon 820 in it, and you’re close to the tower (on a network that supports this technology of course) you could experience a sudden speed boost thanks to higher order modulation.

  • How X12 LTE chooses between LTE and Wi-Fi intelligently

So you know when you walk into your neighborhood coffee shop, and your phone connects automatically to their Wi-Fi hotspot because you’ve connected before? That may not mean you have Internet access—you could be stuck behind a “captive portal” (the dreaded “You must accept these terms and conditions”). So your phone thinks you’re connected to the Internet, but you’re not really. Email? Forget it. Tweets? Not coming in. Somebody just liked your Instagram photo? You would never know—because you’re not really connected.

But Snapdragon 820 with X12 LTE is made to be way smarter than that. When it sees your coffee shop’s Wi-Fi access point, it begins to investigate. Is the signal strong enough? Can I actually, for real, get out to the Internet? How fast is this network anyway—is it faster than my LTE connection, or is that guy with the laptop in the corner hogging up all the bandwidth? And based on that, it can decide whether or not to automatically connect to the coffee shop’s hotspot. Pretty clever, right? Of course, you’re always in charge of overriding the automatic selection if you so choose. 

Qualcomm Snapdragon is a product of Qualcomm Technologies, Inc.