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Currently in my apartament I have a dual band router. In the 5Ghz band I have less powerful signal (-66dBm), but is the only WiFi in the 5GHz band, and I have a more powerful signal in 2.4GHz band (-59dBm), but it has interference from all the 2.4Ghz signals in the building.

2.4 GHz 2.4 GHz

5 GHz

5GHz

Should I choose the less powerful but clear signal at 5GHz? or Should I choose the most powerful but with more interference 2.4GHz signal?

Edit: I found this related question, but I'm dealing here with 2.4GHZ and 5GHz bands, so the answers doesn't apply to my case

Edit2: I think that this question will be misleading because of the difference of 2.4 and 5GHz bands, I don't want to show the difference between the bands, instead I want to know if is better to have a clear channel with low power or a crowded channel with high power

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In general you will want to use the quieter band.

Its difficult to remove the characteristics of 5g vs 2.4g out the equation - and may send you down the wrong track, but this answer will attempt to do that.

There are (at least) 2 aspects here. The more obvious one is this - If there is a significant amount of other traffic in the band, regardless of how much you boost your signal, you are still not going to get the throughput you want as each device needs to get some of the frequency space (ie get its turn) - I am, assuming here that everything is transmitting within the legal limit. [ This ties in with the other aspect, but if you shout loudly enough - you will make the other devices somewhat deaf to the quieter devices and get a bit more throughput, but its an un-winnable arms race, particularly because limits are capped. ]

The 2 advantages of a "louder" router don't help you - they are: 1. They can be heard over a wider distance. 2. The sensitivity of the equipment can be lower and it can perform.

CONCLUSION: A less noisy channel with a low power transmitter will outperform a louder channel with more noise.

The other element (which if you go through the logic in enough depth provides the identical conclusions, but from a different point of view) -

The amount of signal that can be transmitted depends on the difference between the signal and noise (ie the "Signal to Noise Ratio"). Assuming the equipment is very sensitive (ie so sensitivity is not an issue - a claim which is "true enough" for WIFI), you are interested in the ratio of signal to noise - so if you have a transmitter transmitting at 100mw and noise equivalent to 10mw (this is a nonsense - sound is actually measured in DB, but it explains the concept in crude terms) - you will get a ratio of 10:1 - On the other hand if you have a 1 watt transmitter with noise equivalent to 333 watt you have ratio of 3:1 - Thus the quieter signal will allow about 3 times the throughput.

One way you can conceptualize it (light works the same way here) - Look at the sky during the day - you will see very, very few stars because the sun is making your eyes insensitive to light. On a dark night, far away from the city you can see a huge number of stars because there is not a big source of light interference - in this example your eyes act as a receiver, the stars transmitters of various strengths and the sun as a source of noise.

  • This is a great answer. Think of a room full of people having one-to-one conversations. If everyone talks quietly to their partner, conversations can flow quickly. If anyone starts speaking louder, the entire room must adjust their volume and soon it will be too noisy to communicate at all. – Jens Ehrich Dec 8 '16 at 14:41
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this would actually be a better question for electronics.stackexchange.


you should choose the 5ghz spectrum


A 2.4ghz RF signal, due to lower frequency, will penetrate walls and objects more easily.

However, a 5ghz RF spectrum signal has shorter wavelength, and therefor its antenna can be (longer and) better tuned for higher gain within the same space a 2.4ghz antenna would occupy.

Additionally, the 5ghz spectrum has 23 non-overlapping channels, while the 2.4ghz spectrum only has 3. In my experience, there's much less interference, leading to a much cleaner signal, leading to significantly better operation, even more than can gained (oops) from a louder signal.


for now-- until Xfinity/Comcast starts installing 802.11ac/5ghz routers everywhere by default.


finally, if you're running DD-WRT/Tomota-USB or something similar, understand that bumping the radio power will introduce RF harmonics that may hamper the Q-factor of the signal more than help it; not to mention overheat the radio. My wifi radio fried when the cleaning ladies stacked the router/wifi/switch/modem electronics all neatly in one pile.

  • Please check my edit – IAmJulianAcosta Dec 28 '14 at 3:05
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    @IAmJulianAcosta, my comment about "in my experience" still stands and is the takeaway, IMO, from my answer. This is all handwaving, of course. I'd need to know the radiative power of each (2.4ghz radio vs 5ghz radio) to be able to guess further. However, given how many 2.4ghz access points there are all over the place, the empty 5ghz spectrum is going to be hard to beat. – paIncrease Dec 28 '14 at 6:43
  • also, most dual-band routers allow you to run both...does yours? – paIncrease Dec 28 '14 at 6:50
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Interference will kill your throughput. Period.

Therefore, choose the channel without interference.

Also, read about the 'hidden node' problem. It will be exacerbated by strong AP signal.

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Actually the signal power is irrelevant regardless of the band you use. What you do want to know is the signal to noise ratio. in general (but not always) the more other signals on the band the higer the noise. Also depending on the knowledge and experience of the people that setup the other Wifi's this could also cause problems on your own network.

Having said that if you are on a very crowded Wifi area and some of the bands are not being used. There is normally a good reason for it.

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