What is 5G? What's new about the fifth generation

5G is the fifth generation of mobile network technology, the set of standards phones and cell towers have used since 2019 to carry calls and data. Compared with 4G, it was designed to do three things better: move more data, answer with less delay, and connect far more devices in one place. How much of that a user notices depends mostly on which radio band their 5G runs on.

In short

• Each mobile generation is a new set of agreed standards; 5G's are written by the industry body 3GPP and approved by the UN's International Telecommunication Union.
• 5G runs on low, middle and very high radio frequencies: the higher the band, the faster the data and the shorter the reach.
• The scientific consensus is that 5G's radio waves, kept within international limits, have no established harmful effect on health.

What do the "G"s mean?

A "G" is a generation of mobile technology, and each one changed what a phone was for. The dates below are the first commercial launches, as widely recorded.

Generation	First launched	What it added
1G	1979, Tokyo	Analog voice calls on a car or brick phone
2G	1991, Finland	Digital voice (GSM), text messages
3G	2001, Japan	Usable mobile internet, the first smartphones' data
4G	2009, Stockholm and Oslo	Fast data (LTE): video, maps, app stores
5G	2019, South Korea and the US	Much faster peaks, low delay, many devices

The standards are made by 3GPP, a partnership of telecom standards bodies. Its Release 15, which 3GPP calls "the first full set of 5G standards", was delivered in stages: a version that leans on existing 4G networks in late 2017, and a standalone version with its own core network in 2018. South Korea's three carriers switched on 5G for phones late on 3 April 2019, Korean time, and Verizon started service in Chicago and Minneapolis the same day; both claimed to be first. The International Telecommunication Union (ITU) published the formal 5G specification, which it calls IMT-2020, in February 2021, according to its 5G backgrounder.

What does 5G actually change?

Before writing the standard, the ITU set minimum targets in a report known as M.2410, each tied to one way people would use the network:

• Faster data. A peak download rate of at least 20 gigabits a second, for "enhanced mobile broadband": video, downloads, phones in crowds.
• Less delay. Latency, the time a piece of data takes to cross the radio link, of 4 milliseconds for ordinary data and 1 millisecond for "ultra-reliable low-latency" uses such as controlling machines.
• More devices. A density of 1 million connected devices per square kilometer, for sensors, meters and other "massive machine-type" uses.

Those are design minimums for the best conditions, not speeds anyone gets on a phone. Real speeds depend on the band, the distance to the antenna and how many people share it. A little arithmetic shows why the numbers still matter. A 2-gigabyte film is 16,000 megabits. Take two round, illustrative rates. At 50 megabits a second, a good 4G connection, it downloads in 320 seconds, a little over 5 minutes. At 300 megabits a second, a good mid-band 5G connection, it takes about 53 seconds. At the 20-gigabit peak, it would take under a second.

5G also changes how a network is built inside. Its antennas use many small elements to steer narrow beams at each phone rather than broadcasting in every direction, which lets one mast serve more people. Its core network is software running on ordinary servers, so an operator can carve one physical network into separate virtual ones, called slices, with different guarantees: one for phones, one for a factory's robots.

Why is some 5G so much faster than other 5G?

Because "5G" covers very different radio frequencies, and frequency sets both speed and reach. Radio waves at higher frequencies have shorter wavelengths: a 600-megahertz wave is about 50 centimeters long, a 3.5-gigahertz wave about 8.6 centimeters, and a 28-gigahertz wave about 1.1 centimeters, which is why the top band is loosely called millimeter wave. Higher bands have room for wider channels and so more data, but short waves are stopped by walls, leaves, rain and even a hand.

Band	Typical frequencies	Speed	Reach	Where it's used
Low band	Below 1 GHz	Similar to good 4G	Kilometers; goes through buildings	Wide rural and indoor coverage
Mid band	About 1 to 6 GHz, often 3.5 GHz	Several times 4G	Hundreds of meters to a few kilometers	The main 5G layer in most cities
High band (millimeter wave)	About 24 GHz and up	The fastest	Often a few hundred meters, line of sight	Stadiums, stations, dense streets

That is why a phone can show "5G" and feel no faster than 4G: it may be on low-band 5G, or on early 5G that shares the 4G core. The fastest 5G arrives in small patches, where operators have put many small antennas on lampposts and walls.

Is 5G safe?

Yes, on the evidence so far. 5G uses radio waves, the same kind of energy as radio, TV, Wi-Fi and earlier mobile networks. They are non-ionizing: they carry too little energy per photon to break chemical bonds or damage DNA, unlike X-rays or ultraviolet light. Their one established effect on the body is slight heating, and international exposure limits are set well below the level that causes it.

The World Health Organization's Q&A on 5G, published in February 2020, says that "no adverse health effect has been causally linked with exposure to wireless technologies", and that it expects none provided exposure stays below the international guidelines. It also notes that only a few studies had looked at 5G's exact frequencies at the time. Those guidelines come from the International Commission on Non-Ionizing Radiation Protection, whose 2020 update covers frequencies up to 300 GHz, including all of 5G's bands. Higher frequencies penetrate the body less, not more: millimeter waves are absorbed within the skin's outer layers.

Claims that 5G spread COVID-19 were false. A virus spreads between people; radio waves can't carry one, and COVID-19 spread widely in places with no 5G at all.

What does 5G mean for you?

For most people, 5G mainly means faster downloads and fewer slowdowns in crowded places, when the phone is on mid band or better. Some households now use 5G instead of a cable line for home internet, through a box that turns the mobile signal into Wi-Fi. The low-delay and many-devices parts matter mostly to businesses: factories, ports and hospitals running private 5G networks for sensors and machines.

Under the hood, 5G is still a way into the internet. A phone on 5G gets an IP address like any other device, and its data travels from the mast through the operator's network to the wider internet. The next generation, 6G, is being defined now: the ITU published its framework, IMT-2030, in December 2023, and expects the final standards to be approved by 2030.

Check yourself

• Why does a higher radio frequency bring more speed but less coverage?
• What are the three things 5G was designed to do better than 4G, and which one matters most to a factory?
• Why can a phone show "5G" and still feel no faster than 4G?

Sources

• Release 15 — 3GPP, 2019
• Minimum requirements related to technical performance for IMT-2020 radio interface(s), Report ITU-R M.2410 — International Telecommunication Union, 2017
• 5G, fifth generation of mobile technologies — International Telecommunication Union
• Radiation: 5G mobile networks and health — World Health Organization, 2020
• ICNIRP RF EMF guidelines 2020 published — International Commission on Non-Ionizing Radiation Protection, 2020