How 5G technology actually works
We try to cut through all the jargon and sales pitches
Learning basics will help with buying decisions.
FOSTER CITY, Calif. – Most technologies don’t really require you to understand them to appreciate what they can do for you. With 5G, however, things are going to be a little different.
To be clear, you don’t need to know the details of how 5G works to enjoy the potential speed increases and other cool capabilities it eventually will offer. However, you do need to be aware of some 5G basics to really understand what future smartphones, connected devices, and carrier plans are going to offer – and how they’ll differ.
Learning a bit about how 5G works – and why not all 5G is the same – also helps to put some big recent business developments into context. Specifically, the key reasons Apple just spent $1 billion to purchase Intel’s modem business and why wireless spectrum issues were one of the key reasons the merger between Sprint and T-Mobile was just approved by the Department of Justice make much more sense once you understand the technology.
First, some fundamentals.
The basics
Like all cellular networks, the newly launched 5G networks use analog radio signals at various frequencies to transmit data and voice signals from cell towers or other transmitters to your phone or any other broadband wireless connected device. A component called a modem, that’s built into all these devices, receives the signal via integrated antennas and other elements, and converts that signal into digital form.
Conversely, when you send a text, browse a web site, make a voice call, etc., the modem takes the digital signal from inside your device, converts it to analog form, and then sends it via your device’s antennas back out to the network. In other words, modems are absolutely essential devices for smartphones and other devices and that’s why Apple chose to purchase Intel’s 5G modem business.
One of the primary differences with 5G is the frequencies that are used to transmit those signals to and from the cellular networks. While all existing 3G and 4G phones in the US use frequencies that are below 3GHz, most of the action in 5G will be at higher frequencies. This is critically important because radio signals at different frequencies function in very different ways.
As you may recall from your high school science classes (ahem), higher frequency signals don’t travel as far as lower-frequency ones. Think about listening to a concert or other music source off in the distance. You only hear the lower bass tones, not the higher ones. One of the primary reasons this occurs is higher frequencies have shorter wavelengths than lower frequencies.
Why shorter is better
A key benefit of these shorter wavelengths on cellular networks is the ability to transfer data at faster rates – in the case of certain 5G frequencies as much as 60 times as fast as the average rate that current 4G LTE networks have across the US.
There are two critical new groups of frequencies, often called “spectrum,” being used for 5G networks: One is called sub-6 (short for less than 6 GHz) and the other is called millimeter wave (because the wavelength of the signal happens to measure around one millimeter), which uses frequencies around 39 GHz. There are some sub-segments within each of these main groups, and it also is possible to run 5G at frequencies as low as 600 MHz (or 0.6 GHz). However, all these variations still fit within the two main frequency categories.
Will my devices handle it?
Another key point to understand is that not all devices can support all frequencies, nor do all telecom carriers use all frequencies.
In fact, one of the strongest arguments for the recent merger between TMobile and Sprint is that individually, the two companies were arguably at a bit of a disadvantage from a wireless spectrum perspective, but together, they have a much more competitive range of 5G frequencies that they can use over time.
From a frequency perspective, the most important thing to know is that not all 5G offerings are the same. That’s the source of a lot of potential confusion.
The early 5G networks from AT&T and Verizon, for example, all are focused on millimeter wave and require phones or other devices with modems and antennas that support the millimeterwave frequencies, as well as cell towers and transmitters that can send signals at those frequencies.
But what does this really mean?
If you have a millimeter wave-capable 5G phone, for example, and you happen to be close enough to a millimeter wave-generating transmitter, you can get absolutely incredible performance.
In a real-world test I did with the Samsung Galaxy S10 5G on an AT&T network in Hollywood, California, I saw data transfer rates of 1.8 Gbps (gigabits per second). That’s 60 times as fast as the national average of 30 Mbps (megabits per second). In real-world numbers, it’s the difference between downloading an entire season of “Stranger Things” or “Orange Is the New Black” from Netflix in three minutes vs. three hours.
Sounds great. What’s the hitch?
A quick revisit to our basic science facts highlights a few very challenging issues for 5G millimeter wave.
First, because millimeter waves don’t travel very far – typically no more than a few hundred feet – you either have to get very close to a 5G tower or transmitter and just stand there, or, if you want to move around, there have to be a lot of millimeter wave-capable 5G transmitters installed near where you are.
Even worse, millimeter-wave signals are not very strong and cannot penetrate buildings or even windows very well (if at all), so you have to stay outside. Plus, in my experience, you need a direct line-of-sight – as in, you can actually see the transmitter and are pointing your phone at it – to get the best possible speeds.
So are lower-frequency waves better?
In the case of sub-6 GHz 5G, the radio signals can travel much farther than millimeter waves and generally have no issue getting through windows and into buildings. In real-world terms, that means much broader coverage with significantly fewer transmitters.
However, there’s a big trade-off in speed. While the results vary depending on the specific frequencies used, early testing on Sprint’s sub-6 5G network showed speeds up to about 300 Mbps, which is only about 1/6th as fast as millimeter wave but is still 10 times as fast as 4G averages.
One other challenge with sub-6 is that not all 5G modems support all sub-6 frequencies.
So, for example, the Qualcomm X50 modem at the heart of the Samsung Galaxy S10 5G, the LG V50 Thinq, the Motorola Z3 with 5G Moto Mod, and most every current 5G smartphone on the market will not support – and can’t be upgraded to use – the sub-6 frequencies that AT&T and Verizon will be adding to their 5G networks, nor the 600 MHz frequencies with which T-Mobile plans to launch their 5G network later this year.
In fact, that’s part of the reason that several U.S. carriers are not directly selling these first 5G phones to consumers.
The forthcoming Qualcomm X55 modem, as well as future iterations of their Snapdragon processors, will support all these frequencies so that smartphones and other devices that incorporate it won’t have any of these compatibility issues. However, these new devices aren’t expected to arrive until early 2020.
Should I buy 5G devices then?
As you can see, there’s a lot to know about 5G (and believe me, I have only scratched the surface here), but now that you have a better understanding of the technology behind it, you can see why it makes more sense to wait until second-generation devices come around before you jump in.
One more important point to make, however, is that, unlike previous cellular network transitions, 5G won’t completely replace 4G.
It will, instead, work on top of and alongside it. In fact, one of the least appreciated benefits of the move to 5G is that it’s making all of our 4G networks better.
As part of the process of installing 5G-capable equipment into their networks, the big carriers also are upgrading their existing 4G LTE equipment to take advantage of a development known as LTE Advanced (which AT&T confusingly calls 5Ge).
Many newer smartphones already have 4G LTE Advanced-capable modems built in, so in many areas of the country, it’s already possible to get download speeds of up to 150 Mbps, which is five times as fast as the national average. This is one of the many reasons 4G networks and 4G devices will continue to be useful for many years to come.
5G is more than just fast
To be fair, there’s more to 5G than just faster download speeds.
For example, the ability to have less delay, or latency, will be extremely important for future cloud-based gaming applications. In addition, the concept of “network slices” will allow companies, and even individuals, to have their own dedicated swath of bandwidth to run their web-based applications more consistently.
Right now, however, most of the attention is on speed. That’s why it’s important to understand how 5G works so that you can make important buying decisions based on facts and not just hype.