Should one choose channels betwen and other than 1 6 and 11 on the 2.4ghz band?

[LOST TALE]

I figure that while it overlaps with 2 channels, atleast no one's right on top of you!

 

 

[The Pizza Thief]

10 minutes ago, LOST TALE said:

I figure that while it overlaps with 2 channels, atleast no one's right on top of you!

 

 

Use an app on your cellphone to scan the channels occupied in your environment, if most of you neighbors are in one use the option used the least.

[LOST TALE]

2 minutes ago, MultiLito said:

Use an app on your cellphone to scan the channels occupied in your environment, if most of you neighbors are in one use the option used the least.

They are evenly distirbuted on 1 6 and 11, however perhaps it makes sense to choose one to the side of the least occupied channel. like 7 or 4. Is overlapping with a different channel somehow worse than overlapping with an identical one?

 

I just moved mine by 1 channel to the right or left, and omg I went from losing connection at the other end of my house to watching youtube videos trololo

[Alex Atkin UK]

NO, FOR THE LOVE OF GOD NO!

 

If you choose 1, 6 or 11 then the AP can see when other clashing APs are transmitting.  If you choose a channel between, it can't and will try to transmit over the top of other overlapping channel traffic, causing it to be unreliable.

 

To make matters worse, due to how the channels work you will be clashing with 2/3 of the entire spectrum.

[brwainer]

When two nearby APs are on the same channel (nearby determined by whether they can hear each other above a certain strength), each AP will wait a short time to see if something else is broadcasting right now, then do their broadcast once the air is clear, and if it detects a collision due to the other AP(s) also choosing that time to speak up, it will pick a random timer before trying to retransmit.

 

When nearby APs are on overlapping channels, they still employ the same logic, except they will never detect the other device(s) broadcasting, and most of the time couldn’t detect a collision either. Packets that fail to be received intact will either be lost forever (UDP) or have to wait for a timeout and be re-transmitted by the source (TCP). If the APs are sufficiently far apart and/or lightly used, the clients might be able to pick out a high enough percentage of the packets that the net result seems to be an improvement in effective throughput.

 

When the majority of your conflicting APs are on 1, 6, and 11, staying on those as well is the recommended course, otherwise any channel you choose will have significant overlap with other APs. Some people advocate for 1, 4, 8, 11 as that gives one more available channel, with the downside that every channel has minor overlap. This strategy is only effective if you control all the APs in an area (enterprise, hospitality, etc) or can convince all your neighbors to change.

[LOST TALE]

1 hour ago, Alex Atkin UK said:

NO, FOR THE LOVE OF GOD NO!

 

If you choose 1, 6 or 11 then the AP can see when other clashing APs are transmitting.  If you choose a channel between, it can't and will try to transmit over the top of other overlapping channel traffic, causing it to be unreliable.

 

To make matters worse, due to how the channels work you will be clashing with 2/3 of the entire spectrum.

What's AP?

[LOST TALE]

6 minutes ago, brwainer said:

When two nearby APs are on the same channel (nearby determined by whether they can hear each other above a certain strength), each AP will wait a short time to see if something else is broadcasting right now, then do their broadcast once the air is clear, and if it detects a collision due to the other AP(s) also choosing that time to speak up, it will pick a random timer before trying to retransmit.

 

When nearby APs are on overlapping channels, they still employ the same logic, except they will never detect the other device(s) broadcasting, and most of the time couldn’t detect a collision either. Packets that fail to be received intact will either be lost forever (UDP) or have to wait for a timeout and be re-transmitted by the source (TCP). If the APs are sufficiently far apart and/or lightly used, the clients might be able to pick out a high enough percentage of the packets that the net result seems to be an improvement in effective throughput.

 

When the majority of your conflicting APs are on 1, 6, and 11, staying on those as well is the recommended course, otherwise any channel you choose will have significant overlap with other APs. Some people advocate for 1, 4, 8, 11 as that gives one more available channel, with the downside that every channel has minor overlap. This strategy is only effective if you control all the APs in an area (enterprise, hospitality, etc) or can convince all your neighbors to change.

What happens if someone's overlapping AP never stops transmitting? does your AP wait forever?

[mynameisjuan]

31 minutes ago, LOST TALE said:

What happens if someone's overlapping AP never stops transmitting? does your AP wait forever?

There is nothing it can do, collisions with occur and packet loss will happen for both. There are random timers and cell slots used to try to eliminate this but it’s a half duplex medium.

[Alex Atkin UK]

This is one of the things WiFi 6 is hoping to fix, by instead allowing all APs to determine a transmit schedule between each other so that they never transmit at the same time and also get equal time slots, so no one AP can drown out the rest.

 

Unfortunately this will only work once ALL APs on that channel are WiFi 6 so its not going to help residential users for some time, but will be extremely useful for businesses, universities, hotels, etc.

Its why I upgraded my laptop to WiFi 6 because you never know when I might end up in a hotel that had upgraded and it should be a night/day difference.

[brwainer]

3 hours ago, Alex Atkin UK said:

This is one of the things WiFi 6 is hoping to fix, by instead allowing all APs to determine a transmit schedule between each other so that they never transmit at the same time and also get equal time slots, so no one AP can drown out the rest.

 

Unfortunately this will only work once ALL APs on that channel are WiFi 6 so its not going to help residential users for some time, but will be extremely useful for businesses, universities, hotels, etc.

Its why I upgraded my laptop to WiFi 6 because you never know when I might end up in a hotel that had upgraded and it should be a night/day difference.

I’m installing WiFi 6 APs in a hotel this week  but only in the main ballroom  

[Alex Atkin UK]

On 9/24/2019 at 12:21 AM, brwainer said:

I’m installing WiFi 6 APs in a hotel this week  but only in the main ballroom  

I guess that's for conventions?  As I can't see people needing fast Internet when dancing.

[brwainer]

20 minutes ago, Alex Atkin UK said:

I guess that's for conventions?  As I can't see people needing fast Internet when dancing.

Yes its for when the main ballroom gets filled to its fire marshal capacity with everyone’s phones connected at once. Wifi slows to a crawl when you have many clients on an AP, even if they are mostly idle. 802.11ac wave 2 helped with that, but Wifi 6 is going to be revolutionary in that situation (Wifi 6 with just one or two clients on an AP won’t be much faster than Wifi 5).

[Nemesis158]

I use to always have issues with my wireless connection dropping out randomly. living in an apartment complex where there are 30 other APs broadcasting in range all set to automatically choose a broadcast channel, they start jumping around all the time. If you ever have your wifi dropping out on you regularly it is because your AP is switching to a different channel. I always got the best use out of 2.4GHz wifi setting it to an in between channel. I dont use 2.4GHz wifi anymore and my current AP has openWRT running on it so i have access to DFS channels that are completely clear for indoor wifi and use that instead.

[Alex Atkin UK]

2 hours ago, Nemesis158 said:

I use to always have issues with my wireless connection dropping out randomly. living in an apartment complex where there are 30 other APs broadcasting in range all set to automatically choose a broadcast channel, they start jumping around all the time. If you ever have your wifi dropping out on you regularly it is because your AP is switching to a different channel. I always got the best use out of 2.4GHz wifi setting it to an in between channel. I dont use 2.4GHz wifi anymore and my current AP has openWRT running on it so i have access to DFS channels that are completely clear for indoor wifi and use that instead.

The thing you have to remember is just because you might get better performance on an in-between channel, are you screwing over everyone else?

I've had some terrible performance in the past and I think it was caused by rogue ISP provided routers poorly configured to automatically choose in-between channels.  If their AP is more aggressive, it could easily drown out your own, if  your is obeying the specifications more closely.

WiFi is based on fair-sharing of the bandwidth, you shouldn't be doing anything that potentially compromises other peoples use of it.  Heck, I feel guilty that I'm using a ton of 5Ghz spectrum as I have two PtP links with repeaters on the end of each, all on different channels for optimum performance.  But they are at least directional (and not under a constant heavy load) so shouldn't really impact anyone greatly, if at all.

If we don't all play nice, the technology becomes unusable.

[Nemesis158]

4 hours ago, Alex Atkin UK said:

The thing you have to remember is just because you might get better performance on an in-between channel, are you screwing over everyone else?

I've had some terrible performance in the past and I think it was caused by rogue ISP provided routers poorly configured to automatically choose in-between channels.  If their AP is more aggressive, it could easily drown out your own, if  your is obeying the specifications more closely.

WiFi is based on fair-sharing of the bandwidth, you shouldn't be doing anything that potentially compromises other peoples use of it.  Heck, I feel guilty that I'm using a ton of 5Ghz spectrum as I have two PtP links with repeaters on the end of each, all on different channels for optimum performance.  But they are at least directional (and not under a constant heavy load) so shouldn't really impact anyone greatly, if at all.

If we don't all play nice, the technology becomes unusable.

I was using an app that showed APs graphed to channels and saw all the other APs hopping channels too. that would mean everyone else was already experiencing the same connection dropouts too. in a perfect world all the APs would agree on which channels to use to be least disruptive or everyone would manually set them, but that isnt the case.

I would expect that if my being in between channels was causing other connections to not work, would my connection not be worse having 2 sets of overlaps rather than just one?

[Alex Atkin UK]

5 hours ago, Nemesis158 said:

I was using an app that showed APs graphed to channels and saw all the other APs hopping channels too. that would mean everyone else was already experiencing the same connection dropouts too. in a perfect world all the APs would agree on which channels to use to be least disruptive or everyone would manually set them, but that isnt the case.

I would expect that if my being in between channels was causing other connections to not work, would my connection not be worse having 2 sets of overlaps rather than just one?

Which just goes to show how a bad implementation can kill everyones performance.  Its bad practice IMO for APs to constantly flip/flop channels as that way everyone is constantly crashing into each other.  To me its like someone zag-zagging across the road, hogging all the lanes.

My theory for why it might have worked better for you is that when your AP was on a matching channel to the other APs, it was avoiding transmitting over them, but when you moved it between channels it now could only see them as a raise in the noise floor so it DID transmit over them at the cost of speed and latency for everyone.

As your clients were closer to your AP than the others, this ended up being more stable, but much slower than if all the APs had been behaving properly in the first place.  This is the problem when your neighbors APs aren't following the rules either.

There are just so many bad implementations of WiFi, WiFi 6 can't come soon enough.