Understanding Access Point Specs

Sep 25, 2018
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Hi, I'm looking to buy a new access point. I'm trying to understand which 'spec' tells you how far the access point will send its signal. I was told that a N150 access point will not send a signal as far as a N300 access point. Is that true? I thought the 150/300 spec was more about its speed.

Can anyone clarify?
 
Solution
Those number do represent the speed but more they represent the way the data is encoded.

This is the problem with people not understanding terminology and then you have those that intentionally misuse it to manipulate people into thinking their product is better.

In general the range the signal goes is based on the signal level. This is can be easily measured in db, although some device like to fake it and use number of "bars". Apple got caught manipulating that by representing a lower db number as more bars to make it appear their device had better signals.

The problem is DB level does not actually represent how useful the signal is. It only represents the signal strength but it is a very clearly defined concept so you can...
Those number do represent the speed but more they represent the way the data is encoded.

This is the problem with people not understanding terminology and then you have those that intentionally misuse it to manipulate people into thinking their product is better.

In general the range the signal goes is based on the signal level. This is can be easily measured in db, although some device like to fake it and use number of "bars". Apple got caught manipulating that by representing a lower db number as more bars to make it appear their device had better signals.

The problem is DB level does not actually represent how useful the signal is. It only represents the signal strength but it is a very clearly defined concept so you can much more easily compare devices.

This is where things get very messy and people start to combine the concept of data transfer rates with distance. There is no clearly defined way to say what is good or bad. Someone could test all the distances you can transfer at say 50mbps and then test all the distance you can transfer at 55mbps and so on. What is considered a "good" transfer rate is very subjective.

The main mess comes because the stronger the DB level the more likely it is you can successfully use a more complex method of encoding the data which gives more "speed". There is also some point that the db level drops so low that no data encoding method will work even though you can detect the signal.

So if you ask how far can the signal go at 150mbps, more or less a 150mps and 300mbps ap will be equal assuming they have the same db level since they are using the same data encoding. If you ask how far the signal can go at 300m then the 150m device has a zero distance because it does not support the 300m encoding.

The major problem with trying to predict any distance is it is greatly affected by where it is installed. The difference between location the device is installed in is much more than difference in the devices.

In general almost all major brands of devices transmit very close to the legal maximum signal levels. How useful those signal are is impossible to predict both because there is no clear definition of "useful" and the difference in installation locations.

 
Solution
If you're buying new don't get an N. I'd recommend the unifi AP lite. It has AC 2x2 mimo. 2x2 mimo isn't very common on devices yet. It's pretty standard in new APs though.
Assuming your device can connect at the rate advertised the below is a general guestimate.
50% direct line of sight < 5ft away with no wireless congestion or other devices using wifi
30% direct line of sight <15ft average with a few devices
5-20% no line of sight, no outside congestion, a few devices
0-1% high congestion, no line of sight.

To get above 50% you have to test like they do in special RF optimized chambers.
wifi also has a lot of overhead compared to wired, they constantly broadcast so new devices can find it.