What Is 5G? Everything You Need to Know. AT&T, Verizon Wireless and other carriers will start to launch 5G networks this year. But what exactly is 5G? Here's what we know so far.

5G is coming this year. Or maybe not. In the race to 5G, or fifth generation wireless, companies are starting to promise the impossible, which will result in a lot of confusion over the next few years.

Because there isn't any official definition of 5G yet, all the players in the wireless world, from chipset makers to carriers, are jockeying to define 5G and establish themselves as 5G leaders.

So head with me down the rabbit hole that is 5G as I try to explain what the heck is going on.

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

The G in 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," which 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.

AT&T's '5G Evolution' Is Not 5G

AT&T recently announced its "5G Evolution" network, which isn't 5G. It's AT&T's brand for gigabit LTE, the latest incremental advance in 4G LTE, which all major U.S. carriers plan to roll out this year.

Gigabit LTE is backwards-compatible with existing phones and runs on existing spectrum. It uses more advanced versions of LTE's existing encoding, along with more antennas and more efficiently consolidated spectrum, to deliver better speeds.

But AT&T's 5G lie also highlights that LTE isn't going away any time soon. 5G, by and large, will operate on very high frequencies, requiring towers or antennas that are relatively close together. It will rely on 4G for broader overall coverage, especially in rural areas.

4G will continue to improve with time, as well. Qualcomm has already announced a 4G modem, the X20, capable of 1.2 gigabit speeds. The real advantages of 5G will come in massive capacity and low latency, beyond the levels 4G technologies can achieve.

AT&T and Verizon Launching Pre-5G

AT&T and Verizon have both pledged to launch 5G home internet systems this year. At Mobile World Congress in February, Samsung and Verizon showed off the antennas and routers Verizon's 5G service will use.

The technologies used in 5G for the home will be closely related to millimeter wave fixed wireless ISPs such as Starry in Boston and Monkeybrains in San Francisco, but with bigger players such as Verizon and AT&T in the mix, they'll be much more widely available. AT&T, for instance, has talked to me about potentially using 5G to replace its old DSL offerings, letting the company deliver a "quad play" of DirecTV TV service, 5G home internet, wireless phone and home phone.

This isn't quite 5G, because the 5G standard won't be set until 2018. But Verizon intends to converge its 5G service with the actual standard, and it's trying to use as many elements of upcoming 5G systems as possible.

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 U.S., where, according to a 2016 FCC report, 51 percent of Americans only have one option for 25Mbps or higher home internet service.

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.

Okay, So What's 'Real' 5G?

5G is a new network system that has much higher speeds and capacity, and much lower latency, than existing cellular systems. The technologies to be used in 5G are still being defined, but there are many details on which everyone agrees.

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

The new networks will predominantly use very high frequencies that can transmit huge amounts of data, but only a few blocks at a time. The standard will work all the way from low frequencies to high, but it gets the most benefit over 4G at higher frequencies. 5G may also transmit data over the unlicensed frequencies currently used for Wi-Fi, without conflicting with existing Wi-Fi networks. That's similar to a technology T-Mobile is launching this year called LTE-U.

5G networks are much more likely to be networks of small cells, even down to the size of home routers, than to be huge towers radiating great distances. Some of that is because of the nature of the frequencies used, but a lot of that is to expand network capacity.

So 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.

Is 5G for Phones, Cars or Homes?

Driverless cars may need 5G to really kick into action. 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 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-1 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 either Wi-Fi and other home technologies for consumers, or 2G for businesses. 5G networks will accept small, inexpensive, low-power devices, so they'll connect a lot of smaller objects and different kinds of ambient sensors to the internet.

So what about phones? 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 5G encourages every home router to become a cell site.

When Is 5G Happening?

AT&T and Verizon's pre-5G is coming this year, but the first official 5G launches will come in 2018, with broad deployment in 2019. The schedule was previously set for 2019-2020, but carriers and equipment manufacturers figured out an accelerated schedule earlier this year.

This is in line with Qualcomm's 5G modem family announcements. The big chipmaker said that its Snapdragon mobile platform will support 5G in 2019. Snapdragon chips are the most popular platform for U.S. smartphones, so you're likely to see 5G, VR-capable smartphones in 2019.