[SOLVED] When can a neighbouring WIFI access point with a stronger signal knock you out of the connection?

[Rodion15]

I’m confused about co-channel interference and adjacent-channel interference.

When connecting to an SSID, I know it’s best to use an open channel (one that is not being used), but if the spectrum is quite crowded and this cannot be avoided, what would happen?

My understanding is that, if two SSIDs are on the same channel or on very adjacent channels, such as channels 1 and 3 in the 2.4GHz band: it’s best to have a 20dB stronger signal on the one you’ll connect to (such as 40dB vs 62dB) so the other one would be basically “ignored” as it’s weak enough.

My doubt is: what happens if this is not the case?


Here’s an example:

The phone at the bottom of the picture is trying to communicate with SSID1, which the phone is detecting at 62dB, but a neighbour’s access point is using an unlawfully powerful signal, that the phone is detecting at 40dB.

Please correct me if I'm wrong: my understanding is that, even so, if both networks aren’t too crowded, your phone will still communicate, although in non-ideal situation.

In that case, adjacent-channel interference will be worse, as if they are on the same channel, both access points will negotiate the connection and take turns to communicate with their devices.

This article explains why co-channel interference isn't as bad as adjacent-channel interference:

“Co-channel congestion is preferable to adjacent channel congestion because of the way the wireless conversations are managed. As mentioned in our previous article, when choosing a channel that has other networks active, try to keep at least 20 dB between the RSSI levels of the networks”

https://www.metageek.com/training/resources/adjacent-channel-congestion.html



Any clarification much appreciated.

 

[USAFRet]

When can a neighbouring WIFI access point with a stronger signal knock you out of the connection?

Rarely.

The client system...PC/laptop/tablet, is mostly in control of its connection.
They will rarely give up a working connection, even if there is a stronger one available.

 

[bill001g]

The problem is that it will disconnect it is that the data is being damaged and the devices can't get full data packets. They will attempt to retransmit them which increases latency and if they get enough errors the packet will be dropped. In really bad cases of interference it may get enough errors that the AP drops the end user. Mostly it will stay connected and just be very slow because it is getting so many errors.

 

[dwd999]

I’m confused about co-channel interference and adjacent-channel interference.

When connecting to an SSID, I know it’s best to use an open channel (one that is not being used), but if the spectrum is quite crowded and this cannot be avoided, what would happen?

My understanding is that, if two SSIDs are on the same channel or on very adjacent channels, such as channels 1 and 3 in the 2.4GHz band: it’s best to have a 20dB stronger signal on the one you’ll connect to (such as 40dB vs 62dB) so the other one would be basically “ignored” as it’s weak enough.

My doubt is: what happens if this is not the case?


Here’s an example:

The phone at the bottom of the picture is trying to communicate with SSID1, which the phone is detecting at 62dB, but a neighbour’s access point is using an unlawfully powerful signal, that the phone is detecting at 40dB.

Please correct me if I'm wrong: my understanding is that, even so, if both networks aren’t too crowded, your phone will still communicate, although in non-ideal situation.

In that case, adjacent-channel interference will be worse, as if they are on the same channel, both access points will negotiate the connection and take turns to communicate with their devices.

This article explains why co-channel interference isn't as bad as adjacent-channel interference:

“Co-channel congestion is preferable to adjacent channel congestion because of the way the wireless conversations are managed. As mentioned in our previous article, when choosing a channel that has other networks active, try to keep at least 20 dB between the RSSI levels of the networks”

https://www.metageek.com/training/resources/adjacent-channel-congestion.html



Any clarification much appreciated.

There is a free wifi analyzer you can download from the microsoft store. You can use it to analyze your neighborhood signals and manually choose a different channel with the least likely chance of interference.

 

[Rodion15]

Rarely.

The client system...PC/laptop/tablet, is mostly in control of its connection.
They will rarely give up a working connection, even if there is a stronger one available.

Thanks again!