"Nationwide 5G" is here, but for many people, it doesn't seem to be making much of a difference. For our Fastest Mobile Networks 2020 tests, we went to 26 cities to test 5G on all three major US carriers. We found that AT&T's and T-Mobile's 5G feels a lot like 4G, and while Verizon's 5G feels radically different, it has very little coverage.

That may lead people to wonder what the big deal is with 5G. Is what we're seeing right now even 5G at all? The answer is yes—technically. It turns out that 5G technology and a "5G experience" are very different things, and right now in the US we're getting the former without the latter.

5G is an investment for the next decade, and in previous mobile transitions, we've seen most of the big changes happening years after the first announcement. Take 4G, for instance. The first 4G phones in the US appeared in 2010, but the 4G applications that changed our world didn't appear until later. Snapchat came in 2012, and Uber became widespread in 2013. Video calls over LTE networks also became big in the US around 2013.

With the 5G transition, there's another twist. There are three main kinds of 5G—low-band, mid-band, and high-band—and while the US put its bet on low and high, it turns out that mid-band is probably the best way to do it. Here in the US there aren't much in terms of mid-band airwaves available for 5G. The government is playing catchup and will auction some off at the end of 2020.

So following that plan, while we're getting fits and starts of 5G right now, you should expect the big 5G applications to crop up around late 2021 or 2022.

1G, 2G, 3G, 4G, 5G

First of all, if you're hearing about 5G Wi-Fi or AT&T's "5G E" phones, they aren't 5G cellular. Here's a full explainer on 5G vs. 5G E vs. 5GHz: What's the Difference?

And if you're hearing that 5G means millimeter-wave towers on every lamppost, that's not true. That's only one of the three main forms of 5G we're seeing right now.

The G in this 5G means it's a generation of wireless technology. While most generations have technically been defined by their data transmission speeds, each has also been marked by a break in encoding methods, or "air interfaces," that make it incompatible with the previous generation.

1G was analog cellular. 2G technologies, such as CDMA, GSM, and TDMA, were the first generation of digital cellular technologies. 3G technologies, such as EVDO, HSPA, and UMTS, brought speeds from 200kbps to a few megabits per second. 4G technologies, such as WiMAX and LTE, were the next incompatible leap forward, and they are now scaling up to hundreds of megabits and even gigabit-level speeds.

5G brings three new aspects to the table: bigger channels (to speed up data), lower latency (to be more responsive), and the ability to connect a lot more devices at once (for sensors and smart devices).

It isn't a clean break with 4G. 5G phones all need 4G networks and coverage. Initially, all 5G networks used 4G to establish their initial connections, something called "non-standalone." We're moving away from that now into "standalone" networks, but there's still no standard for voice calls over 5G yet. So every time you want to make a phone call, your phone has to fall back to 4G. Part of the 5G spec also allows 5G phones to combine 5G and 4G channels invisibly and seamlessly to the user.

That symbiosis between 4G and 5G has caused AT&T to get a little overenthusiastic about its 4G network. The carrier has started to call its 4G network "5G Evolution," because it sees improving 4G as a major step to 5G. It's right, of course. But the phrasing is designed to confuse less-informed consumers into thinking 5G Evolution is 5G, when it isn't.

This all means in part that while the US carriers will turn off their 2G and 3G networks in the next few years, 4G has many years ahead of it as part of the 5G equation.

Low, Middle, and High

5G gives carriers more options in terms of airwaves than 4G did. Most notably, it opens up "high-band," short-range airwaves that didn't work with 4G technology. But 5G can run on any frequency, leading to three very different kinds of 5G experiences—low, middle, and high.

The key thing to understand here is that 5G speeds are directly related to how wide the available channels are, and how many are available. With 4G, you can combine up to seven, 20MHz channels to use a total of 140MHz of spectrum. Most of the time, though, phones are using 60MHz or less.

With current phones in low- and mid-band 5G, you can combine two 100MHz channels, for 200MHz usage—and stack three more 20MHz 4G channels on top of that. In high-band 5G, you can use up to eight 100MHz channels. The great speeds 5G carriers promise are just about leveraging more airwaves at once. But if you don't have the airwaves available, you don't get the speeds.

Carriers can also flexibly share channels between 4G and 5G using dynamic spectrum sharing, or DSS. DSS makes the walls between 4G and 5G channels movable, so carriers can split channels between 4G and 5G based on demand. 

Low-band 5G operates in frequencies below 2GHz. These are the oldest cellular and TV frequencies. They go great distances, but there aren't very wide channels available, and many of those channels are being used for 4G. So low-band 5G is slow. It acts and feels like 4G, for now. Low-band 5G channels are from 5MHz in width (for AT&T) up to 15MHz (for T-Mobile), so you can see they aren't roomier than 4G.

Complicating things, AT&T and T-Mobile low-band phones sometimes show 5G icons when they aren't even using 5G, making it hard to tell any difference.

Mid-band 5G is in the 2-10GHz range. That covers most current cellular and Wi-Fi frequencies, as well as frequencies slightly above those. These networks have decent range from their towers, often about half a mile, so in most other countries, these are the workhorse networks carrying most 5G traffic. Most other countries have offered around 100MHz to each of their carriers for mid-band 5G. Here in the US, T-Mobile is currently using up to 60MHz of mid-band for 5G, although it owns more that it currently can't use. AT&T and Verizon will shave off little bits of their 4G spectrum using DSS for mid-band 5G, 10MHz here and 10 there. A fresh 280MHz, known as the C-Band, will be auctioned off at the end of 2020 for use starting in 2021.

High-band 5G, or millimeter-wave, is the really new stuff. So far, this is mostly airwaves in the 20-100GHz range. These airwaves haven't been used for consumer applications before. They're very short range; our tests have shown about 800-foot distances from towers. But there's vast amounts of unused spectrum up there, which means very fast speeds using up to 800MHz at a time. Verizon relies extensively on high-band, which it calls "ultra wideband." AT&T has some, in small parts of 35 cities. T-Mobile has a bit, more broadly, in seven cities. Unfortunately, we found in our Fastest Mobile 2020 tests that Verizon's network had as little as four to five percent coverage on our citywide drives.

High bands have been used before for backhaul, connecting base stations to remote internet links. But they haven't been used for consumer devices before, because the handheld processing power and miniaturized antennas weren't available. Millimeter-wave signals also drop off faster with distance than lower-frequency signals do, and the massive amount of data they transfer will require more connections to landline internet. So cellular providers will have to use many smaller, lower-power base stations (generally outputting 2-10 watts) rather than fewer, more powerful macrocells (which output 20-40 watts) to offer the multi-gigabit speeds that millimeter-wave networks promise. Because of the very fast drop-off, the waves are quite weak when they get to you.

In many major cities, the carriers installed these "small cells" to increase 4G capacity starting in 2017. In those cities, they just need to bolt an extra radio onto the existing site to make it 5G. There's a struggle going on elsewhere, though, where carriers are having trouble convincing towns to let them add small cells to suburban neighborhoods. That's similar to previous struggles over establishing cellular service at all in many of these towns. 

Verizon is trying to enhance its high-band 5G coverage by making deals with companies that create 5G extenders and repeaters, like Pivotal Commware.

How 5G Works

Like other cellular networks, 5G networks use a system of cell sites that divide their territory into sectors and send encoded data through radio waves. Each cell site must be connected to a network backbone, whether through a wired or wireless backhaul connection.

5G networks use a type of encoding called OFDM, which is similar to the encoding that 4G LTE uses. The air interface is designed for much lower latency and greater flexibility than LTE, though.

With the same airwaves as 4G, the 5G radio system can get about 30 percent better speeds thanks to more efficient encoding. The crazy gigabit speeds you hear about are because 5G is designed to use much larger channels than 4G does. While most 4G channels are 20MHz, bonded together into up to 140MHz at a time, 5G channels can be up to 100MHz, with Verizon using as much as 800MHz at a time. That's a much broader highway, but it also requires larger, clear blocks of airwaves than were available for 4G.

That's where the higher, short-distance millimeter-wave frequencies come in. While lower frequencies are occupied by 4G, by TV stations, by satellite firms, or by the military, there had been a huge amount of essentially unused higher frequencies available in the US, so carriers could easily construct wide roads for high speeds.

5G networks need to be much smarter than previous systems, as they're juggling many more, smaller cells that can change size and shape. But even with existing macro cells, Qualcomm says 5G will be able to boost capacity by four times over current systems by leveraging wider bandwidths and advanced antenna technologies.

The goal is to have far higher speeds available, and far higher capacity per sector, at far lower latency than 4G. The standards bodies involved are aiming at 20Gbps speeds and 1ms latency, at which point very interesting things begin to happen.

Where Is 5G Available?

5G is now "nationwide," although with the carrier's very different approaches to it, you're going to have different experiences in different places.

Verizon has fast, high-band 5G in parts of 35 cities, with online coverage maps here.

T-Mobile currently has a slow nationwide low-band 5G network that covers most of the country; mid-band in five cities, with a coverage finder here; and high-band in seven cities (the ones listed in that link, plus Miami). 

AT&T has slow low-band across about most of the country and high-band in 35 cities, which it doesn't give maps for and is unnecessarily confusing about the coverage of. It calls the low-band "5G" and the high-band "5G+." 

Which 5G Phones Are Coming Out?

5G phones are mainstream now, and the recent launch of Apple's iPhone 12 line is likely to greatly boost 5G phone adoption. It's also the only US phone so far that's been approved to use band n77, the "C-Band" for 5G that is likely to give AT&T and Verizon good mid-band 5G coverage in 2021.

There are plenty of 5G Android-based phones available, and they've even started to get affordable; the new T-Mobile Revvl 5G comes in at under $400. They aren't all the same in terms of 5G capabilities, though.

Low- and mid-band 5G is less expensive to implement than high-band 5G, so many AT&T and T-Mobile phones lack high-band 5G. Currently, the only phones on AT&T and T-Mobile to have all forms of 5G at once are the Samsung Galaxy S20+, the Samsung Galaxy S20 Ultra, the Samsung Galaxy Note 20, and the Samsung Galaxy Note 20 Ultra.

There's also a difference in terms of software. On T-Mobile, we found earlier this year that the OnePlus 7T Pro 5G McLaren and OnePlus 8 received critical software upgrades to improve low-band performance before the Samsung phones did. Yep, that means the OnePlus phones worked better on low-band but lacked high-band, while the Samsung phones had high-band but did worse on low-band. It's messy.

Our Fastest Mobile Networks 2020 results don't show much of a reason to buy a 5G phone on AT&T right now, as AT&T's 5G is often slower than its 4G. Another reason to wait is that AT&T has said it will rely on new carrier aggregation capabilities in Qualcomm's X60 modem, which will first appear in phones such as the presumed Galaxy S21 next year.

On T-Mobile and Verizon, on the other hand, our Fastest Mobile Networks tests have shown that getting a 5G phone absolutely does improve your overall speeds, as long as you have 5G coverage.

Other countries have many more 5G phones, with models from Huawei, Oppo, Realme, Xiaomi, and others hitting shelves around the world. They generally don't work on US 5G networks because they don't support our frequency bands; they use European and Asian mid-band systems we don't have here.

Is 5G Safe?

Yes. Online conspiracy theories have blamed 5G for everything from cancer to coronavirus, but they tend to fall apart at the slightest tap of actual facts. Low-band and mid-band 5G are based on radio frequencies that have been used for decades. Low-band 5G uses UHF TV bands, which have been in use since 1952. Sprint's mid-band has been in use at least since 2007; parts of it were first used in 1963.

The greatest 5G worries in the US tend to be around high-band, or millimeter-wave, 5G. This is the short-range type that requires a lot of small cell sites, so the infrastructure is more visible than it was before. The ironic thing about worrying that millimeter-wave will fry your cells isn't that it's too strong, but that it's too weak—it's blocked by leaves, walls, glass, cars, clothing, and skin. 

Power levels are extremely important. Bluetooth and microwave ovens run on the same frequency. Because millimeter-wave signals are technically called microwave, some people are convinced they are literal microwave ovens that will fry us. But a firefly isn't a blowtorch—and the 5G systems are more on the firefly end of things.

Studies of mmWave have shown that it doesn't penetrate human skin well and that its strongest effect, at levels of power higher than any 5G network uses, is that it makes things slightly warmer. At the levels 5G networks use, there's no perceptible effect on people.

But the most self-condemning thing about the mutable 5G conspiracists is that they don't care about any of these details. A popular petition in the UK in early 2020 claimed that 5G runs at "60 megahertz" and is "sucking all of the oxygen out of the air." It got more than 114,000 signatures on change.org before being deleted. 60 megahertz is much lower than any wireless network frequency; they might mean 60GHz, but no 5G network is using that yet, either. As for the oxygen, well, there's a network of pseudo-scientists with degrees in things like "natural health" who are claiming all sorts of complete nonsense on YouTube.

Here's a good UK story that digs into the details about 5G safety. Phone Scoop also has a strong article on the issue from the US perspective.

What's 5G For?

Most of the real-world 5G demos we've seen just involve people downloading Netflix very quickly on their phones. That kind of usage is table stakes, just to get the networks built so more interesting applications can develop in the future.

On phones, OnePlus CEO Pete Lau said that 5G could make onboard storage irrelevant, which dovetails with ideas I heard around the launch of the Samsung Galaxy S20. The Galaxy S20 takes huge 108-megapixel photos and 8K videos, which quickly eat up your storage and are difficult to upload, unless you have a fast 5G connection. On a trip to Korea, I found that high-quality video chat was a major driver for wanting 5G.  

5G home internet shows one major advantage over 4G: huge capacity. Carriers can't offer competitively priced 4G home internet because there just isn't enough capacity on 4G cell sites for the 190GB of monthly usage most homes now expect. This could really increase home internet competition in the US, where, according to a 2016 FCC report, 51 percent of Americans only have one option for 25Mbps or higher home internet service. For its part, Verizon says its 5G service will be truly unlimited.

5G home internet is also much easier for carriers to roll out than house-by-house fiber optic lines. Rather than digging up every street, carriers just have to install fiber optics to a cell site every few blocks, and then give customers wireless modems. Verizon chief network officer Nicki Palmer said the home internet service would eventually be offered wherever Verizon has 5G wireless, which will give it much broader coverage than the carrier's fiber optic Fios service.

Verizon has dragged its feet on bringing 5G home internet to more than the five cities it serves right now, largely because it's waiting for home modems that use the newer Qualcomm QTM527 antenna. This antenna module can greatly extend the range of high-band 5G networks. It's too big and power-hungry to go into phones, but it's perfect for home units. The last I heard from Verizon, these modems will come out later this year. Inseego, among others, wants to make these home modems.

On a trip to Oulu, Finland, where there's a 5G development center, we attended a 5G hackathon. The top ideas included a game streaming service; a way to do stroke rehab through VR; smart bandages that track your healing; and a way for parents to interact with babies who are stuck in incubators. All of these ideas need either the high bandwidth, low latency, or low-power-low-cost aspects of 5G.

We also surveyed the 5G startups that Verizon is nurturing in New York. At the carrier's Open Innovation Lab, we saw high-resolution wireless surveillance cameras, game streaming, and virtual reality physical therapy.

Our columnist Michael Miller thinks that 5G will be most important for industrial uses, like automating seaports and industrial robots.

Driverless cars may need 5G to really kick into action, our editor Oliver Rist explains. The first generation of driverless cars will be self-contained, but future generations will interact with other cars and smart roads to improve safety and manage traffic. Basically, everything on the road will be talking to everything else.

To do this, you need extremely low latencies. While the cars are all exchanging very small packets of information, they need to do so almost instantly. That's where 5G's sub-one-millisecond latency comes into play, when a packet of data shoots directly between two cars, or bounces from a car to a small cell on a lamppost to another car. (One light-millisecond is about 186 miles, so most of that 1ms latency is still processing time.)

Another aspect of 5G is that it will connect many more devices. Right now, 4G modules are expensive, power-consuming, and demand complicated service plans, so much of the Internet of Things has stuck with Wi-Fi and other home technologies for consumers, or 2G for businesses. 5G will accept small, inexpensive, low-power devices, so it'll connect a lot of smaller objects and different kinds of ambient sensors to the internet.

The biggest change 5G may bring is in virtual and augmented reality. As phones transform into devices meant to be used with VR headsets, the very low latency and consistent speeds of 5G will give you an internet-augmented world, if and when you want it. The small cell aspects of 5G may also help with in-building coverage, as it encourages every home router to become a cell site.