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ansky
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Ce+eC vs Ce+Ce on overlapping channels

Wed Jun 12, 2024 12:48 am

I have two access points using channel 36 (40 MHz) that overlap each other. Should I set Ce on the first AP and eC on the second, or should I use Ce on both?

If I use Ce on the first and eC on the second, their beacons won't interfere. But what about data transmission? Doesn't channel access coordination happen on the primary channel? Will the second AP listen to the traffic from the first AP and decide to wait on transmitting if a transmission is already happening? Is the listening only on the primary channel or both?

If I set Ce on both, their beacons will interfere, but will this ensure that transmissions won't interfere?

Note: Ce and eC refer to different channel configurations. "Ce" means the primary channel is the first 20 MHz (in this case, channel 36) and the extension channel is above it (channel 40). "eC" means the primary channel is the second 20 MHz (channel 40) and the extension channel is below it (channel 36).
 
neki
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Re: Ce+eC vs Ce+Ce on overlapping channels

Wed Jun 12, 2024 2:39 am

May I ask you, why do you use same channel on both devices?
 
ansky
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Re: Ce+eC vs Ce+Ce on overlapping channels

Wed Jun 12, 2024 2:48 am

May I ask you, why do you use same channel on both devices?
Unfortunately I can't answer that.
 
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Re: Ce+eC vs Ce+Ce on overlapping channels

Wed Jun 12, 2024 2:52 am

Because it's top secret or because you don't know?
 
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Nullcaller
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Re: Ce+eC vs Ce+Ce on overlapping channels

Wed Jun 12, 2024 8:35 am

I quickly tested two routers and two clients on both Ce+eC and Ce+Ce with some speedtesting action, and it's pretty much the same bandwidth-wise, so it seems like collisions are avoided effectively in both scenarios. Latency-wise, to me, it seemed like Ce+eC was better, but I could be imagining things.

Ce+eC is also what routers usually will do when forced to operate on one channel, but otherwise left to their own devices, so I would think this is the optimal option. Of course, some default behaviors in routers are quite dumb, look no further than 2.4 GHz channel selection. (for newer devices, can we just adopt 1-5-9-13 scheme, ditch 802.11b and be done with it already?) But it seems like they also learned on their mistakes, judging by channel organization in the 5GHz band.

I was curious too, and was able to find exactly zero info on the Internet about this, besides a Reddit post that was largely unanswered, so I imagine that to confirm or disprove that Ce+eC is, in fact, better, you will probably need to find someone who actually read the FM, i.e.e.e. the 802.11 standard. I would love to be that guy, but just the 2020 version of it is 4379 pages long (it's probably even longer now with WiFi 7), and my attention span is far too short.
 
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Ca6ko
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Re: Ce+eC vs Ce+Ce on overlapping channels

Thu Jun 13, 2024 12:32 pm

Using channel 36 it is not possible to tune the eC extension as it is the lowest channel in the band, it is forbidden to use frequencies lower than this. Therefore, only Ce can be used on channel 36. Then the points will use channels 36+40 when working in the 40 mHz band.
Channel 36 (5180) occupies frequencies 5170-5190 mHz when operating in the 20 mHz bandwidth
Channel 40 (5200) occupies frequencies 5190-5210 mHz
 
ansky
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Re: Ce+eC vs Ce+Ce on overlapping channels

Sun Jun 23, 2024 8:08 am

Using channel 36 it is not possible to tune the eC extension as it is the lowest channel in the band, it is forbidden to use frequencies lower than this. Therefore, only Ce can be used on channel 36. Then the points will use channels 36+40 when working in the 40 mHz band.
Channel 36 (5180) occupies frequencies 5170-5190 mHz when operating in the 20 mHz bandwidth
Channel 40 (5200) occupies frequencies 5190-5210 mHz
What I meant by eC on channel 36 is that 40 would be the primary and 36 the extension channel. Otherwise the frequencies would not be overlapping. So on mikrotik you'd configure the frequency as 5170-5210.

Btw, in my country channel 32 (5150 to 5170) is legal. I'd appreciate it if mikrotik added support for channel 32, as well as channels 68 and 96. It'd give mikrotik an edge in crowded places.
 
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Re: Ce+eC vs Ce+Ce on overlapping channels

Sun Jan 19, 2025 12:45 am

Btw, in my country channel 32 (5150 to 5170) is legal. I'd appreciate it if mikrotik added support for channel 32, as well as channels 68 and 96. It'd give mikrotik an edge in crowded places.
In Singapore as well. Channel 32 (5150-5170) is non-DFS. Channels 68 (5330-5350) and 96 (5470-5490) are DFS channels. It'd be great to have them in the tool bag. Here's Singapore's entry from db.txt in the Linux wireless-regdb:
country SG: DFS-FCC
	(2400 - 2483.5 @ 40), (200 mW)
	(5150 - 5250 @ 80), (200 mW), AUTO-BW
	(5250 - 5350 @ 80), (100 mW), DFS, AUTO-BW
        # This range ends at 5725 MHz, but channel 144 extends to 5730 MHz.
        # Since 5725 ~ 5730 MHz belongs to the next range which has looser
        # requirements, we can extend the range by 5 MHz to make the kernel
        # happy and be able to use channel 144.
	(5470 - 5730 @ 160), (500 mW), DFS
	(5725 - 5850 @ 80), (1000 mW)
	(5945 - 6425 @ 320), (250 mW), NO-OUTDOOR
	(57000 - 66000 @ 2160), (10000 mW)
And here's the reg-info readout from RouterOS 7.16.2 on a hAP ac3:
country: Singapore
number: 0
  ranges: 2402-2482/20
          5490-5730/24/dfs
          5735-5835/30
          5250-5330/24/dfs
          5170-5250/24
As you can see, Channels 32, 68, and 96 are missing in RouterOS, but they're allowed in Linux's wireless-regdb.

Have you received any feedback from MikroTik development about this request?