The coverage of the home Wi-Fi network is an issue that affects all homes today. We can have the best optical fiber in FTTH technology that reaches us inside the house, but from the router onwards, the speed of the Internet connection largely depends on where we have placed the router and how the house is made. Walls, corridors, furniture, and obstacles of various kinds can literally cut off the best Internet connection, bringing us back to the era of the first ADSL.
A good way to solve Wi-Fi network coverage problems is to use one or more Wi-Fi access points, which extend the signal using different technologies: from a simple Wi-Fi extender that replicates the signal to complex mesh networks made by multiple routers.
The problem, however, is not solved only by installing these devices. A lot also depends on where we place them because, paradoxically, if we place them badly, we could get even lower network performance. To understand where to place the Wi-Fi access points, we need to start from a bit of theory.
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How Wi-Fi networks work?
Modern Wi-Fi routers all work on two main frequency bands: the old 2.4 GHz and the new 5 GHz. As many know, 2.4 GHz transmissions are not very fast, but they are stable and can go far. Also, they are able to penetrate walls and obstacles quite well. The 5 GHz, on the other hand, has a higher band, and therefore a higher connection speed but a lower range and penetration capacity.
Moving from theory to practice, we must introduce the unit of measurement dBm, which stands for “decibel milliwatt” and indicates the strength of a radio signal. This power decreases as we move away from the source of the transmission (the router or the access point) and every obstacle that the signal must cross. A wall, for example, “steals” on average between 3 and 6 dBm based on its composition and thickness.
To achieve good Wi-Fi performance, a device must receive a signal of at least -65 dBm. Dropping to -70 dBm, the performance still remains acceptable, but not brilliant. At -75 dBm, we can start to have real connection problems. If there are no obstacles in between, a 2.4 GHz signal maintains -65 dBm up to a distance of 18-20 meters, while a 5 GHz signal does not go beyond 8-10 meters. These are theoretical values because possible interference does not count. However, it is useful to understand how much difference in the range there is between a 2.4 and one at 5 GHz signal and how much even a single large wall can affect the range of the signal. Therefore, the golden rule to follow in a Wi-Fi connection is the following: no more than two rooms, no more than two walls.
Too much power can be a problem.
Between theory and practice, however, there are the complex rules of physics and the intrinsic ones that regulate the functioning of Wi-Fi devices. Given the above, one might believe that the closer we are to the router or access point, the better the signal will be. But that’s not the case: the forums are chock-full of people solving their connection problems by moving away from, and not getting close to, the source of the broadcast. Because they were simply too close to the router or access point.
A correct distance between two devices that communicate via Wi-Fi signals avoids signal overlaps, which do nothing but penalize the performance of the network but, unfortunately, there is no universal minimum distance to be respected. Each router has a different antenna configuration; therefore, a good suggestion is to move the device away from the router one meter at a time until you get the best performance. Of course, in light of what has been said so far, there will be a distance beyond which performance will start to drop. We will have to stop just a little earlier.
Use the full spectrum of frequencies.
Another golden rule for achieving good performance in a Wi-Fi network is to use all available frequencies to avoid congestion. So, for example, if we have a desktop PC at the right distance from the router or from the access point, we can choose to have them communicate using the 5 GHz band in order to leave the 2.4 GHz frequencies free (which, we remember, arrive further away) for a device in the next room. If, on the other hand, we have many devices in the same room, it is good to distribute them on different frequencies in order to avoid congesting just one.
Virtue lies in the middle.
In light of the above, we can now give an example of where to place an access point. Let’s say the area to be covered with the signal is ten meters long in total, with two walls in between. In such a scenario, it is very likely that if we place the access point at one end of the area, we will have a rather weak signal at the other end. At 10 meters, a 2.5 GHz signal has about -60 dBm (theoretical), but subtracting two walls also drops to -70 or even -80 dBm (real). A 5 GHz signal at 10 meters has a power of -65 dBm (theoretical); adding two walls the power collapses. The best solution, in such cases, is to place the access point between the two walls: in this way, the signal, to reach the extremes of the area, will have to go halfway through the road and cross only one wall instead of two.
The signal over the obstacle
But it’s not just the walls – everything actually draws power from the Wi-Fi signal, even people and animals. Also, for this reason, Wi-Fi connections in very crowded offices always give problems: you want or don’t want, there will always be someone passing in front of the access point.
Of course, it is not possible to prevent people from moving around the house or office, but it is possible to avoid that the signal has to pass through other “fixed” obstacles such as cabinets, shelves full of books, or interfere microwave placed in the middle. A good rule of thumb is to place the access point high above the height of our head. This way people will be almost bypassed and, most likely, most of the furniture too.
To have a stable and fast Wi-Fi signal throughout your home, you need to use two or more signal repeaters. The golden rules for arranging them are enumerated above.