# Wireless Access

Contributor II

## Could the noise affect the RSSI ?

Hi Guys,

Could the noise affect the RSSI?

Even the noise is very high, but I think it may not be able to affect the RSSI, right?

Aruba Employee

## Re: Could the noise affect the RSSI ?

That is correct. But it'll affect the SNR.

Thanks,

Rajaguru Vincent

Thanks,
Rajaguru Vincent
CWNA | CWSP | CWAP | CWDP | ACMP
Contributor II

## Re: Could the noise affect the RSSI ?

Thanks,

But what would happen if  STA get a very high RSSI but a very low SNR?

Because in RF Optimization profile, the AP only measures the RSSI.

Does the AP send a deauth to the STA?

Aruba Employee

## Re: Could the noise affect the RSSI ?

Hi,

If RSSI is high, then SNR should also be high.

For example,

Noise floor =  -90 dBm

SNR = 55 (high SNR)

If RSSI is low,

Noise floor = -90 dBm

SNR = 10 (low SNR)

In RF optimization profile, the RSSI threshold value can be 1-255. Here RSSI is not measured in dBm, but a relative measure of signal strength on a scale of 0-255.

Thanks,

Rajaguru Vincent

Thanks,
Rajaguru Vincent
CWNA | CWSP | CWAP | CWDP | ACMP
Contributor II

## Re: Could the noise affect the RSSI ?

What if we increace the noise only, would the RSSI be affected by the high noise?

For example:

Noise floor =  -90 dBm

SNR = 55 (high SNR)

Some how, the noise floor increaced, maybe some one turned on a oven, then

Noise floor =  -50 dBm

Would the RSSI still be -35 dBM?

Even if the RSSI still be -35 dBM, would the controller send a deauth to the STA because of the low SNR?

Guru Elite

## Re: Could the noise affect the RSSI ?

It's a ratio..

Sent from Nine

| Tim Cappalli | Aruba Security | @timcappalli | timcappalli.me |

NOTE: Answers and views expressed by me on this forum are my own and not necessarily the position of Aruba or Hewlett Packard Enterprise.
Aruba Employee

## Re: Could the noise affect the RSSI ?

Hi,

Noise floor usually won't go that high in real world.

RF optimization profile will look at only the RSSI. Noise or the SNR change will not trigger a deauth. If RSSI goes low, it will trigger a deauth.

Thanks,

Rajaguru Vincent

Thanks,
Rajaguru Vincent
CWNA | CWSP | CWAP | CWDP | ACMP
Contributor II

## Re: Could the noise affect the RSSI ?

Yes , it's a ratio.

We shouldn't say RSSI = -35 dBM， but RSSI can be convert to Power Value.

Like RSSI 50* K = -35 dBM , every vendor have a different K value.

Contributor II

## Re: Could the noise affect the RSSI ?

I think this a design flaw, Controller should measure bothe the SNR and RSSI.

Aruba Employee

## Re: Could the noise affect the RSSI ?

ClientMatch does that. RF optimization profile is an old one.

Thanks,

Rajaguru Vincent

Thanks,
Rajaguru Vincent
CWNA | CWSP | CWAP | CWDP | ACMP