min rssi unifi

[QwertyJuan]

Has anyone do this?? Wanting to deploy this here at work.... just wondering. What is a "good" min RSSI?? I am seeing some places 25 and some 20.

Any experience guys??

 

[klank]

I would set it no lower than 15. I have mine set to 20.

 

[QwertyJuan]

Ok.... I have it set to 20. Does that mean anyone with -80 and lower should be forced to a different AP??

 

[klank]

Ok.... I have it set to 20. Does that mean anyone with -80 and lower should be forced to a different AP??

Yes.

All it does it disassociates them from the AP they are connected to, which forces the client device to search for another AP with a stronger signal. Helps prevent sticky clients.

If the client reconnects to that same AP it will not disconnect them again due to low RSSI. Supposedly.

 

[QwertyJuan]

Yes.

All it does it disassociates them from the AP they are connected to, which forces the client device to search for another AP with a stronger signal. Helps prevent sticky clients.

If the client reconnects to that same AP it will not disconnect them again due to low RSSI. Supposedly.

So if I have a ton of these deployed in a smallish area (end of this week I'll have 8 in a 130x90 building), wouldn't I want it set really high (say like 30 or so) so that the connected device is always grabbing the nearest unit??

P.S. I have them all turned down quite low and have played with channels enough that I don't have any interference between units... so no issues there. I am just deploying so many because I am sometimes having 150 wireless clients in the building at the same time.

 

[klank]

So if I have a ton of these deployed in a smallish area (end of this week I'll have 8 in a 130x90 building), wouldn't I want it set really high (say like 30 or so) so that the connected device is always grabbing the nearest unit??

P.S. I have them all turned down quite low and have played with channels enough that I don't have any interference between units... so no issues there. I am just deploying so many because I am sometimes having 150 wireless clients in the building at the same time.

First enable Load balancing under Wireless Networks > Options "Balance number of clients per radio" set it to 20-30 max. This way you won't overload a single AP.

Secondly you don't want to set the min RSSI too high because it can cause excessive roaming and increase battery drain of stations. Now each site is going to be different so you may want to experiment with different settings to see how it reacts in your specific environment. My suggestions are simply a starting point.

 

[QwertyJuan]

First enable Load balancing under Wireless Networks > Options "Balance number of clients per radio" set it to 20-30 max. This way you won't overload a single AP.

Secondly you don't want to set the min RSSI too high because it can cause excessive roaming and increase battery drain of stations. Now each site is going to be different so you may want to experiment with different settings to see how it reacts in your specific environment. My suggestions are simply a starting point.

Yes... I have load balancing set to 25 right now. I first noticed it the other day when I had nearly 50 people on one AP.... I went and moved a few AP's around and ordered a new one as well. It seems like with lower output power and repositioning I am getting more even coverage. The RSSI was my next "experiment".

 

[QwertyJuan]

Ok, just an update... not sure if it's just me or not... but had a TON of problems after I implemented min RSSI.... I'd pick up my phone and it wouldn't be connected to wifi at all. I would have to either start walking around OR shut it off and turn it back on. Removed the min RSSI file and problems went away. Gonna stay away from it for now...

Just wanted to post it for people in the future.

 

[/usr/home]

Ok.... I have it set to 20. Does that mean anyone with -80 and lower should be forced to a different AP??

No, not quite. A RSSI of 20 gives you a SNR of 13. If the noise floor of your AP is -90 then you are saying any client weaker than -77, kick.

I'd recommend not going below a RSSI of 20. 20 gives you a SNR of 13 which is quite low. You usually want to aim for a SNR of 20 or higher generally speaking.

In higher density clusters of APs I set the RSSI usually around 35-40. For more "outlier" APs I set it to 20-25.

 

[klank]

You do not get SNR just from the RSSI value, you have to have the noise floor to calculate the SNR.

However with that being said Ubiquity states the following:

"Minimum RSSI works by kicking wireless clients that fall below the configured RSSI threshold. RSSI is a vendor-specific value. With UniFi, RSSI & SNR are synonymous. As long as a user remains above the RSSI threshold (SNR), they won't be kicked. To learn how to configure minimum RSSI for UniFi, click here. So if the Minimum RSSI value is 20dB, clients whose SNR drops to 19dB, 18dB, etc. will be kicked, allowing them to find a better access point."


To answer the OPs question. If the client is at -80 and the noise floor is at -90 then the client will have an SNR of 10 which would result in kick. If the client is at -69 RSSI and noise at -90 then they would have -21 SNR so they would stay associated until their SNR drops. All assuming the min RSSI is set to 20.

You can check the noise floor by SSHing into each AP and running the iwconfig command.

 

[/usr/home]

You do not get SNR just from the RSSI value, you have to have the noise floor to calculate the SNR.

However with that being said Ubiquity states the following:

"Minimum RSSI works by kicking wireless clients that fall below the configured RSSI threshold. RSSI is a vendor-specific value. With UniFi, RSSI & SNR are synonymous. As long as a user remains above the RSSI threshold (SNR), they won't be kicked. To learn how to configure minimum RSSI for UniFi, click here. So if the Minimum RSSI value is 20dB, clients whose SNR drops to 19dB, 18dB, etc. will be kicked, allowing them to find a better access point."


To answer the OPs question. If the client is at -80 and the noise floor is at -90 then the client will have an SNR of 10 which would result in kick. If the client is at -69 RSSI and noise at -90 then they would have -21 SNR so they would stay associated until their SNR drops. All assuming the min RSSI is set to 20.

You can check the noise floor by SSHing into each AP and running the iwconfig command.

RSSI and the dBm level of the clients are not the same. I made a chart of the SNR to RSSI conversion values for the UAPs.

That said, the percentage of the connection shown on the controller does not match the RSSI OR the dBm level. It's calculated differently.

 

[klank]

RSSI and the dBm level of the clients are not the same. I made a chart of the SNR to RSSI conversion values for the UAPs.

That said, the percentage of the connection shown on the controller does not match the RSSI OR the dBm level. It's calculated differently.

I never said SNR and RSSI was the same, Ubiqity did. I said you cannot calculate SNR without signal and noise.

Source for the UniFi #s?