I personally don't think "5G" is going to matter much for most people. For what people actually want (higher cell phone bandwidth), it's more marketing hype than anything else.
First off, the 3GPP (the standards body that develops most mobile radio technologies) doesn't actually use terms like "3G", "4G" and "5G". They instead define releases, each one defining a collection of features. Equipment manufacturers don't advertise a "G" number but instead claim compatibility with a particular release, augmented with selected features from later releases (e.g. Release 10 with cherry-picked features from releases 11-14).
If you manage to talk to an engineer and ask what "5G" is, he will say it means that the radio signals support the 5G New Radio (NR) specification (from 3GPP release 14), which incrementally enhances LTE and LTE-Advanced. But 5G-NR can run at any frequency and support any bandwidth, so that is of almost no concern to end users.
He may also talk about other features from 3GPP releases 12-14 or describe the new technologies in the "packet core" network that network operators run in order to route your phone's mobile data packets to/from the various voice networks and Internet gateways needed to complete the connections, but again, these definitions are only going to be of interest to someone who is either designing/building equipment or operating a mobile network.
With respect to what (non-industrial) customers are going to care about, they want faster data rates on their cell phones. All the rest is meaningless buzzwords and marketing hype that they are told will deliver these faster data rates. And (I think) most people are going to be disappointed, at least until the operators roll out far more equipment than they have so far.
Why? It's a matter of bandwidth. Newer radio technologies (GSM, CDMA, LTE, 5G-NR, etc.) are able to pack more bits into a given radio band, but physics imposes upper limits, especially in real-world conditions where you can never get a completely clean signal.
5G-NR radios may use two different regions of spectrum. Frequencies below 6 GHz (so-called "sub-6") are the same frequencies that have always been used for cell phones, from the first-generation analog cell phones right up through the latest 4G standards. Some operators are reusing these legacy bands (e.g. from now-disabled 1G, 2G and 3G services) for 5G service. The 5G-NR encoding can definitely provide more bandwidth than the 2G and 3G encodings it replaces, but it's not going to be a huge boost, simply because the bands themselves are pretty narrow (typically 5-20 MHz per channel), and there's no way to expand that, because the neighboring bands are owned by other companies and are dedicated for other uses. For example, see T-Mobile’s 600MHz 5G peaks at roughly 225Mbps, but there are caveats.
Where 5G really shines is in the millimeter-wave spectrum, with frequencies in the 10's of GHz. There's nothing magical about high frequencies correlating to high bandwidth, but the fact that these frequencies are (mostly) unused means that regulators were able to define bands that are about 3 GHz wide - each one is half the size of the entire sub-6 spectrum region! When operating in these bands, channel bandwidths may range from 50-400 MHz. It is these much wider channels that allow the 5G-NR technology to provide throughput in the gigabit/s range.
The problem with millimeter-wave is that the signals have very limited range. They are significantly attenuated by commonplace things like trees and glass windows. You can't have a millimeter-wave access point provide service to several square miles of space - the signal would be almost undetectable for most of the region. This is why the focus for millimeter-wave is on urban environments where there are (hopefully) enough customers to make it cost effective to install an access point every 1-2 blocks on a street.
Outside of big cities, areas that will benefit from 5G technology are likely to be:
- Large crowds – stadiums, conference centers, outdoor festivals. Places where an operator can install lots of small access points throughout a building, or where they can be brought in on trucks for temporary use.
- Inside large buildings – co-locating access points with Wi-Fi access points to provide coverage where 4G signals from outside towers can't reach.
- Private cellular networks, where a location owner runs his own network (issuing its own SIM cards for employees and equipment). This appears to be highly desirable for operators of large factories, mines and similar locations. It is effectively replacing Wi-Fi and proprietary radio technologies. This is being done, to a small extent, with LTE, but 5G is expected to run over radio bands that have less regulation (e.g. the CBRS bands), allowing site owners to deploy cellular technology with much less legal red tape.
Other 5G technologies, designed for IoT, are likely to be far more widely deployed, but you won't see them on your cell phones. For instance, Narrowband IoT is an LTE-Advanced/5G technology for very low-power devices. It has very low bandwidth, making it useless for cell phones but perfectly adequate for smart appliances like light bulbs, thermostats and door locks that need to maintain a connection to the network but move very little data most of the time.
In short, I wouldn't worry much about 5G in your cell phone. If you live in a big city where millimeter-wave is being deployed, it may let you experience the high bandwidths everybody's marketing department is talking about, but for most other places, the improvements are not going to be very dramatic and (if you live in an area with a weak signal), you may not even notice them. This will, of course, change in a few years as operators expand their 5G networks (both sub-6 and millimeter-wave), but I don't think 5G in a phone is really going to be important for most people until then.
I think Apple would be far better off supporting the highest-bandwidth LTE-Advanced standards in order to take advantage of everything 4G operators are providing today and deploy 5G technologies in a year or two when most people can actually use and benefit from them.
At least that's my opinion. I could, of course, be wrong.
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