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New Member
Posts: 22
Registered: ‎11-02-2017
Solutions: 1

AP LR - Should I reduce transmit power ?

Before I setup my first UniFi network (at home, I'm a entusiat, not a networking pro) I spent some time reading and asking questions on this community. I was lead to believe I needed at least 2 (or 3) APs to cover my house.

 

I went I head and got a LR (based on suggestions) expecting that I could use results from this one to determine how many more I would be needing.

 

For my surprise, with default settings it is able to cover my whole house, both floors and the areas outside that matters to me (driveway and backdoors).

 

However... I read in many different places that "Transmit Power" should never be left on auto. 
If I understood it right, auto is same as max power and the recommended practice it to bring it down.

Does it mean I will loose coverage and then need additional devices?

 

I'm looking at a lot of numbers I don't quite understand (yet) so I really appreciate any comments/advice that will help me understand what I should do next and why.

 

AP Settings

 

2018-09-13_16-15-43.jpg

 

Heat MAP from Controller

I'm not sure if I did this one right but here it goes anyways:

 

2018-09-13_16-17-41.jpg

 

Survey App on an Android Phone

 

I'm no expert so I don't know how good or bad these numbers are but all locations passed at least my daughters test: Watch random YouTube videos:

 

First Floor

 

First Floor.jpg

 

Second Floor

 

Second Foor.jpg

  

 

Thanks in advance.

Emerging Member
Posts: 70
Registered: ‎05-15-2017
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Re: AP LR - Should I reduce transmit power ?

hello , from what i see is that you already have very good covrage , and about the output power  , mostly , the 3 ap will talk to each other and see how much signal they are recieving from each other , if the power is too much , it will be reduced automaticly , i think you are good like this , + you can know if you are really good jsut by doing some speedtests on speedtest.net to see if you are getting full advantage of you 3 new aps , if not , you can ask further questions about power or even positioning .

New Member
Posts: 22
Registered: ‎11-02-2017
Solutions: 1

Re: AP LR - Should I reduce transmit power ?

@khialnet I was told by multiple people that I may need 2 or even 3 APs however, what you see above is from a single AP LR unit. The fact that it is really good is somehow concerning me.

 

It got me thinking that maybe people who suggested I would need more than one AP were thinking of some specific configuration that may impact the APs range, I don't know.

 

Also I'm concerned with the APs life, if by using Auto (max power?) I'm not reducing its life.

 

This is from my iPhone, right on top of the AP, pretty much same thing I get from a wired connection.

 

IMG_1229.PNG

 

This is me at the place where the survey app measured -62 dBm (second floor, bottom of the map).
Tt is a 45% drop in speed but since my internet connection is relativelly fas, it is still pretty good if you ask me:

 

IMG_1228.PNG

 

Regular Member
Posts: 634
Registered: ‎01-06-2017
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Re: AP LR - Should I reduce transmit power ?

 

The normal recommendation is to reduce the 2.4 GHz power to low or medium.  You can usually leave 5 GHz on high if you want.

 

If you have only one AP, and it works like it is, you can leave it with no significant concerns. If you have nearby neighbors and your signal is bleeding into their yard, you might want to reduce power to be a good neighbor.

 

There are several reasons for the reduced power recommendation. Most of them apply to multiple AP setups, so they do not apply to you:

1. If you have more than one AP, you don't want their signals overlapping too much or you can have trouble roaming between APs.

2. 2.4 GHz travels farther than 5 Ghz through typical building materials.  Reducing the 2.4 band compared to the 5 GHz band makes the coverage area more similar for the two bands.  This helps avoid devices sticking to 2.4 when they should connect to 5 Ghz. On the other hand, if you want coverage in the yard, you will want higher power on 2.4.

3. Another reason to reduce power is to have the range of the AP more closely match the range of of a portable device.  If you use too high power, you may find that you get a connection to the AP from far away, but are unable to use it because your device doesn't have enough power to talk back to the AP.

 

 

 

 

Emerging Member
Posts: 72
Registered: ‎03-17-2014
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Re: AP LR - Should I reduce transmit power ?

I'm sure someone from UBNT would give you a definitive answer, but my understanding is the LR units are so called because of a combination of a better receive sensitivity and a higher output power.

 

With a wireless connection between two devices, there's no point in having a higher output power on one device than the other - the link is limited by the weakest device's ability to talk back, but this can be compensated for a little bit by a superior receive sensitivity of the more powerful radio.

 

In saying that, if your phone is receiving -40 dBm from the AP, it might dial its own power output back on the basis that it thinks you're close to the AP so a high output power (and corresponding battery drain) is not needed. If that -40 dBm is a result of a ridiculously powerful radio that's actually a long way away, then the AP might not have a good signal from your phone, which isn't matching the output power. Your phone would show full signal but the performance would be bad.

 

I'm not an expert though - there might well be a mechanism by which the AP and station negotiate this stuff between them these days. I've definitely seen this phenomenon back in the day of the 2.4 only UAP-LR though.

 

Generally I'd go for the standard APs, put more in and dial the power back, but if you're getting acceptable performance now then why change anything?

Regular Member
Posts: 634
Registered: ‎01-06-2017
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Re: AP LR - Should I reduce transmit power ?

 


@willpage wrote:

 

With a wireless connection between two devices, there's no point in having a higher output power on one device than the other - 

 


People often say this, but consider a scenario like streaming an HD video to a tablet.  In cases like this the data is primarily one way, and there is no need for the tablet to have the same power (e.g. connection speed) back to the AP, because the tablet is not sending much data back to the AP.

 

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