this post was submitted on 07 Dec 2023
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It seemed like a bunch of hype from the beginning to me. I looked up the specs of my old Motorola phone from 2017 back when 5G was a new topic, and the 4G LTE modem in that old phone is capable of 600Mb data speeds. But no 4G LTE connection ever gave me much more than 40-50Mb on speed tests.
5G rolled out and I have a 5G phone (not because it's 5G but because it's my new phone) and whenever I do a speed test, the results are no better than 4G LTE. But there was a trade-off for the "upgrade" to 5G - the cell towers for 5G have much less range than the 4G ones do. So not only do I receive no improvement in speed but the towers' range is downgraded.
There's physics reasons that 5g is theoretically faster, while also having lower range. It's related to the frequency used. All other things being equal, higher frequency radio waves attenuate faster in any given medium than lower frequency waves. (Their range would effectively be identical in a vacuum.) But, the total number of waves you can transmit in any given period is inversely proportional to attenuation.
As you approach a bitrate that is equal to the frequency, you start to run up against the limits of physics in terms of how much information you can transmit. Choosing a frequency arbitrary to illustrate: 900 MHz. At 900MHz, there are 900 million waves going out per second. In some perfect universe, you could turn the signal on/off up to 900 million times per second, giving you a theoretical bitrate of 900Mbit, or 112MB/s. In reality, you never approach this limit, due to error correction and a bunch of other things, so you might get a tenth of that speed as your practical maximum from an engineering perspective. So maybe 10MB/s. There are other tricks you can do, like MIMO on multiple adjacent frequencies, but that is a digression.
But if you go from 900 MHz to 2.4GHz, you automatically gain a reprieve from the physics, allowing you to potentially gain 2.7x the speed. Amazing! Only, now the signal is absorbed by materials 2.7x faster, and has trouble penetrating through walls as well and such. Yikes!
So you have a tradeoff. 4G is a lower frequency than 5G. 5G makes more sense in very dense open environments: stadiums, concerts, busy outdoor markets, etc. where you need a lot of bandwidth in a small area without a lot of obstacles. 4G will penetrate the walls of your house better, at lower theoretical top speeds. Phones can and should switch to whatever is optimal for the environment you're in.
We're near the limit of physics on these things and I don't expect things will evolve a lot more from here.
I think you might be talking about 5G mmWave which is really high frequency and really impractical in most cases due to requiring clear line of sight. Other than that 5G is used on the same bands / frequencies that 4G is and it's just utilizing them slightly better.
Ah, you're probably right.