For each new technology, figuring out what it can do is only half the problem.  Figuring out what it will be used for is the other half.  Often new technology is a solution looking for a problem.

When mobile phones started they were like this.  A few people needed (or wanted) mobile communication, but PMR (Private Mobile Radio) provided this since the war.  Not many needed the ability to contact more than a select list, and were not prepared to pay the high cost or carry around the brick and brief case needed to make it work.  Then the personal compact phone came along, the internet bloomed and putting the two togther 3G took off and a large proportion of the poulation now have a phone permanently held to the side of their head or play the diddle-ooh-da, diddle-ooh-da, diddle-ooh-da, dee tune in the middle of concerts.

Growth from 2000 to 2009

I am not sure what 1G and 2G were, the brick was presumably one of them, but once the small mobile phone came along, the generations ceased to be a matter of the hardware.  A mobile phone is a mobile phone and it has internet connectivity or not according to how much you are prepared to pay your service provider.  If your phone can connect to the internet, download apps and videos, send and recieve texts, play tunes and games then it is known as a smart phone, if it can only work as a telephone then it is just a phone.  They are not actually called stupid phones.  What does 3G, 4G, 5G mean?

Many phones now can do either 3G or 4G and it comes down to your contract.  When 3G first came out the internet was still fairly new and not everyone had it.  Now, not only do most people have internet access but they also use it a lot.  It has become an essential part of our lives.  3G is no longer as fast as it used to be with all the streaming going on, so many have switched, or are switching, over to 4G which is faster.  However in busy places like airports and train terminuses it can be so congested competing for bandwidth, that 4G can be just as slow as 3G was.

So will 5G be the same, initially a bit faster, but soon becoming just as clogged as people demand more?  There is a danger of this, since there will be new demands on 5G; driverless cars and the internet of things (IOT) for example.  However when 3G and 4G were planned there was no internet and most people did not appreciate how popular the mobile phone and internet would become.  By the time 5G was planned some lessons had been learned.  Whether they will be enough remains to be seen.  Traffic has a knack of expanding to fill the available capacity.  But there is an order of magnitude change in 5G.  We need to look at some figures.

Top speed is what you get when no one else is competing with you for bandwidth.  It is noticeable how each generation improves on the top speed.  This is acheived by using higher radio frequencies and improved electronics.  However average speed is what you get when competing with others, and is what you can expect normally.  So looking at speed alone it doesn't look like 5G brings much.  Hardly enough to keep up with growth.  So let's look at the next chart

Latency is basically response time.  It is the time between when a request leaves your phone and the response comes back.  There are two components to latency, the time it takes for the signals to travel over the network [Network Latency] and the time it takes the server to analyse your request and prepare the response [Server Latency], it is only the former we will consider here.  We will assume the server has the next message ready for you when the request comes in.

It is much harder to compare latency as it is quoted as a range rather than a single figure.  In some cases latency on a 3G network can be longer than on a 2G network other times it will be shorter.  For 3G to 4G it should mostly be half the time, it could be less or it could be more.  For 4G to 5G, the worst case (the slowest 5G response compared to fastest 4G reponse) is one fifth of the time, but it could be only 100th of the time.  It is the improvement in latency that will make 5G a game changer.  Providing we don't swamp it with unforseen increased demand.

5G is different to its predecessors in certain specific ways.  Instead of radiating signals in all directions as is normal in radio comunications, a broadcast system, 5G utilizes targeted beams more like radar.  This enables far more traffic of data on the same frequencies, which reduces congestion.  Also a wider spectrum of frequencies will be used, of itself this increases the bandwidth.  Because all the practical uses of 3G and 4G weren't anticipated, nor how popular it would be, the planners did not expect us to use so much data.  Now that we know we need the capacity, with everything connected to the internet, more (enough?) will be made available.

The end result is to release a constraint on the existing tech, that which we already have.  Your phone will work where it currently struggles.  You will be able to watch replays on your phone at the stadium with the configurations you choose, alongside everyone else in the stands doing their own thing.  And this improvement will enable functions to actually work, ones that we inherently need to be highly reliable to bother with using them at all.  This is one of the dangers.  5G will release a demand that isn't there at present, so is very hard to forecast.

Car crashes could become a thing of the past, or reduced to non-fatal bumps, with self-driving cars that have reaction speeds 1,000 times faster than human ones.  If that is only true while you have got good reception, it is not much good.  But that is what 5G aims to fix.  Let us hope the planners have got it right.  One thing that should be improved is motorway pile-ups.  The chatter between the initial vehicles will alert those behind to slow down, even though the humans are busy arguing and not paying attention.  The half to one second reaction time will be reduced to millseconds.  A vehicle travels 170 yards in half a second at 70 mph.  Have you ever seen those traffic cam clips of huge lorries hurtling at full speed into the back of a stationary queue.  They should be compulsory viewing for all drivers.

5g has been designed to be very much faster, but we will see if they have got it right

3rd December 2019