5G is the fifth generation of standards for mobile telephony. This technology fuels many societal debates on its environmental impact, on possible consequences on health, or simply its usefulness, let's focus on the technological aspects.
How does 5G work? Is this a real technological breakthrough or more simply an improvement of past generations?
A little history
Before we take a closer look at 5G, let's take a look at the older generations. The first (1G) was introduced in the 1980s, unlike the following ones, it was an analog system. Its main application was in car phones.
The 2G is introduced in 1992, one passes to a digital system, with telephones able to make calls and short messages (SMS). This generation also made possible the first data transmissions at very low speed, that is to say at the speed of the first modems to access the Internet.
From 2000 to 2010, it is the era of 3G, the main improvement is the faster data transmission, to achieve a speed of a few Megabits / s with 3G⁺, allowing smooth navigation on the Internet. It is also the arrival of touch screen terminals that have exploded the use and traffic of data on networks.
Then, from 2010 until today, we switched to 4G, with much higher speeds of 10 Megabit / s to access streaming videos in particular.
Always faster
So here is 5G, the main objective is still to speed up data transmission, we should have an average speed of 100 Megabit / s with peaks of a few Gigabit / s in the most favorable cases (10 to 100 times faster than 4G).
This is not a major technological breakthrough, but rather improvements from the old generation. Indeed, the technology is based on the same principles as that of 4G: it is the same waveform that will be used, the same principle of transmission.
This is called OFDM. This makes it possible to make transmissions in parallel: by a mathematical treatment, we manage to make a large number of transmissions on very similar frequencies. This, therefore, allows more information to be transmitted at the same time. In 4G, we were limited to 1,200 parallel transmissions, while in 5G, we will be at 3,300 with, also, increased speed for each transmission.
At first, 5G is a complement to 4G: the smartphone is connected in 4G, and transmission is done in 5G only if high speed is necessary and, of course, if the area is well covered in 5G..
A more flexible network
The network that will be deployed will be configurable, therefore more flexible. Before, operators used dedicated hardware to operate networks. For example, the location database essential to reach a mobile subscriber was manufactured by telecom equipment manufacturers.
Ultimately, the 5G network will make much more use of computer virtualization technologies: the location database is a bit like an extremely secure web server that can run on one or more PCs. The same is true of the various controllers making it possible to ensure the correct routing of the data when the subscriber moves in the network. The advantage is that the operator can start virtual machines to, for example, adapt to an increased demand for users in certain areas or at certain times, and on the contrary reduce the capacities if few people are present.
It is therefore possible to reconfigure a network when the load is low (for example at night) by grouping the controllers and databases on a small number of computers and thus achieve energy savings.
New branches
As we have seen, since 5G technology is not very different from the previous technology, it would have been possible to use the same frequencies as for 3G networks for example.
The operators and state bodies that allocate the frequencies have chosen to use other frequencies. This is for several reasons: to satisfy an ever-increasing demand for speed and not to penalize users who would like to continue using older generations. Responding to the growth in traffic requires increasing the microwave spectrum (i.e. frequencies) devoted to mobile networks and this is only possible by using higher frequency ranges: 3.3 GHz very soon and probably 26 GHz in the future.
Finally, putting a new technology into service requires a testing and refining phase before commercial opening. Switching to 5G on a band currently used for another technology would significantly reduce the quality perceived by users (temporarily for owners of 5G phones, definitely for others) and would not fail to cause complaints from many customers.
To transmit at new frequencies, it is not necessary to increase the number of sites with cell towers; however, new antennas must be deployed on the existing masts. These include a large number of small antennas and, thanks to signal processing algorithms, have more directional radiation that can be finely controlled. The advantage is to have a more efficient transmission in terms of speed, but also of energy.
To understand, we could make an analogy with flashlights and laser pointers. The flashlight, representing the old antennas, illuminates in a diffuse way in all directions and consumes a lot of electricity to finally illuminate relatively little far. The laser, on the contrary, will consume less energy to illuminate further, but in a very narrow way. Regardless of the antenna technology, the maximum power of the electromagnetic field produced in any direction should not exceed the maximum permitted values for health reasons.
So if these new antennas use less power, is 5G less voracious? One might think so, because each transmission of information will consume less, but unfortunately, the exchanges being more and more numerous, overall, it should consume more. The use of new frequencies can, moreover, only lead to an increase in the electricity consumption of operators.
New applications
When launching a new technology on the market, it is difficult to predict all the applications, rather they come after and are caused by other players. That said, we can already imagine several avenues.
5G will allow a much lower latency time between sending and receiving data. Take the example of a surgeon operating remotely with a mechanical arm. When the robot touches a part of the body, the operator will be able to "feel" almost instantaneously (of the order of a few ms for a distance of a few kilometers) the resistance of what it touches and react accordingly, like s 'he operated with his own hands. Low latency is also useful for self-driving cars and remote vehicle driving.
For manufacturers, we can think of connected and automated factories in which a large number of machines will have to be able to communicate with each other and with the global network.
5G is also one of the technologies that will enable the development of the Internet of Things. By equipping a city with sensors, it is possible to better manage public lighting, vehicle flows, waste collection, etc. Electricity can also be better controlled with real-time consumption adaptation to production by multiple small interconnected units, called smart grids.
For the general public, the increase in the speed of the network will make it possible to download all types of files more quickly or to be able to view live or streaming videos of very high quality.