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ste
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Channel overlap 802.11ac

Thu Sep 11, 2014 6:29 pm

Is it possible to work with overlapping extension channels in .ac?

E.g. I have a sector with Ceee and one with eeeC on the same site.
The eee Channels overlap each other.

I would like each sector only using his C-Channel until traffic requires to
use the e Channels. If both operate at full speed they use Ce and eC.
If one is loaded while the other is quiet I would like to see Ceee and C.

Is this possible?
 
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rextended
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Re: Channel overlap 802.11ac

Fri Sep 12, 2014 10:05 am

"ac" simply convert 5GHz unoverlapped channel, on 5GHz full overlapped channels, like 2.4GHz.

The best is to not use 80MHz channels.
 
ste
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Re: Channel overlap 802.11ac

Fri Sep 12, 2014 10:22 am

"ac" simply convert 5GHz unoverlapped channel, on 5GHz full overlapped channels, like 2.4GHz.

The best is to not use 80MHz channels.
As I understand .ac can do channel usage/selection more intelligent than 11n.
There goes my question. We often have sectors with low usage near sectors with
high usage so balancing channels between sectors would help increase tower
bandwidth.
 
0ldman
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Re: Channel overlap 802.11ac

Fri Sep 12, 2014 7:34 pm

As Ste says, it is suppose to be a feature of 802.11ac.

It is related to the backwards compatibility as well. Depending on load and client capability it *should* be able to dynamically go between 20MHz to 160MHz wide channels.

The question is really does it work in practice as well as theory.
 
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saintofinternet
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Re: Channel overlap 802.11ac

Wed Apr 22, 2015 11:18 am

"ac" simply convert 5GHz unoverlapped channel, on 5GHz full overlapped channels, like 2.4GHz.

The best is to not use 80MHz channels.
when the world is working towards a better speed with the 'ac' why are you asking to avoid it?
 
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rextended
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Re: Channel overlap 802.11ac

Thu Apr 23, 2015 4:05 am

because "ac" actually do not add any new frequencies...
simply overlap all previous frequencies.

For example, on Italy the frequency range usable go from this two edges: 5490 - 5710

With 20MHz channel are available 11 channels: no one single channel is overlapped.

5500, 5520, 5540, 5560, 5580,5600, 5620, 5640, 5660, 5680, 5700


With 40MHz channel (20+20 = Ce = eC or 40MHz "turbo mode" as on some wlan chipset ), one channel are fully overlapped with the next or previous.
The total unoverlapped combinations are only 5:

5500 + 5520 Ce (= 5520 + 5500 eC)
5540 + 5560 Ce (= 5560 + 5540 eC)
5580 + 5600 Ce (= 5600 + 5580 eC)
5620 + 5640 Ce (= 5640 + 5620 eC)
5660 + 5680 Ce (= 5680 + 5660 eC)
5700 Ce unusable: 5700 + 20 MHz > 5710

Overlapped channels with previous list:
5500 eC unusable: 5500 - 20 MHz < 5490
5520 + 5540 Ce (= 5540 + 5520 eC)
5560 + 5580 Ce (= 5580 + 5560 eC)
5600 + 5620 Ce (= 5620 + 5600 eC)
5640 + 5660 Ce (= 5660 + 5640 eC)
5680 + 5700 Ce (= 5700 + 5680 eC)

With 60MHz channel (20+20+20 = Cee = eCe = eeC ), one channel are fully overlapped with the next or previous TWO!
Like previous example, the total unoverlapped combinations are only 3, LIKE 2,4GHz BAND!!!

5500 + 5520 + 5540
5560 + 5580 + 5600
5620 + 5640 + 5660
5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

With 80MHz channel (20+20+20+20 = Ceee = eCee = eeCe = eeeC ), one channel are fully overlapped with the next or previous THREE!
Like previous example, the total unoverlapped combinations are only 2:

5500 + 5520 + 5540 + 5560
5580 + 5600 + 5620 + 5640
5660 + 5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

and if you see the "ac" standard, it can use also 160MHz channels. only one channel available:
5500 + 5520 + 5540 + 5560 + 5580 + 5600 + 5620 + 5640 Ceeeeeee ...... eeeeeeeC
5660 + 5680 + 5700 + xxxx + xxxx + xxxx + xxxx + xxxx unusable: 5700 + 20 MHz > 5710


This demostrate how 802.11ac make previous unoverlapped 5GHz band,
full overlapped and unusable band worst than 2,4GHz band.
 
ste
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Re: Channel overlap 802.11ac

Thu Apr 23, 2015 9:03 am

because "ac" actually do not add any new frequencies...
simply overlap all previous frequencies.

For example, on Italy the frequency range usable go from this two edges: 5490 - 5710

With 20MHz channel are available 11 channels: no one single channel is overlapped.

5500, 5520, 5540, 5560, 5580,5600, 5620, 5640, 5660, 5680, 5700


With 40MHz channel (20+20 = Ce = eC or 40MHz "turbo mode" as on some wlan chipset ), one channel are fully overlapped with the next or previous.
The total unoverlapped combinations are only 5:

5500 + 5520 Ce (= 5520 + 5500 eC)
5540 + 5560 Ce (= 5560 + 5540 eC)
5580 + 5600 Ce (= 5600 + 5580 eC)
5620 + 5640 Ce (= 5640 + 5620 eC)
5660 + 5680 Ce (= 5680 + 5660 eC)
5700 Ce unusable: 5700 + 20 MHz > 5710

Overlapped channels with previous list:
5500 eC unusable: 5500 - 20 MHz < 5490
5520 + 5540 Ce (= 5540 + 5520 eC)
5560 + 5580 Ce (= 5580 + 5560 eC)
5600 + 5620 Ce (= 5620 + 5600 eC)
5640 + 5660 Ce (= 5660 + 5640 eC)
5680 + 5700 Ce (= 5700 + 5680 eC)

With 60MHz channel (20+20+20 = Cee = eCe = eeC ), one channel are fully overlapped with the next or previous TWO!
Like previous example, the total unoverlapped combinations are only 3, LIKE 2,4GHz BAND!!!

5500 + 5520 + 5540
5560 + 5580 + 5600
5620 + 5640 + 5660
5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

With 80MHz channel (20+20+20+20 = Ceee = eCee = eeCe = eeeC ), one channel are fully overlapped with the next or previous THREE!
Like previous example, the total unoverlapped combinations are only 2:

5500 + 5520 + 5540 + 5560
5580 + 5600 + 5620 + 5640
5660 + 5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

and if you see the "ac" standard, it can use also 160MHz channels. only one channel available:
5500 + 5520 + 5540 + 5560 + 5580 + 5600 + 5620 + 5640 Ceeeeeee ...... eeeeeeeC
5660 + 5680 + 5700 + xxxx + xxxx + xxxx + xxxx + xxxx unusable: 5700 + 20 MHz > 5710


This demostrate how 802.11ac make previous unoverlapped 5GHz band,
full overlapped and unusable band worst than 2,4GHz band.
This is why a synced solution is needed. Using Frequencies Back2Back doubles the usable spectrum on a tower.
 
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chechito
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Re: Channel overlap 802.11ac

Sun May 03, 2015 1:25 am

because "ac" actually do not add any new frequencies...
simply overlap all previous frequencies.

For example, on Italy the frequency range usable go from this two edges: 5490 - 5710

With 20MHz channel are available 11 channels: no one single channel is overlapped.

5500, 5520, 5540, 5560, 5580,5600, 5620, 5640, 5660, 5680, 5700


With 40MHz channel (20+20 = Ce = eC or 40MHz "turbo mode" as on some wlan chipset ), one channel are fully overlapped with the next or previous.
The total unoverlapped combinations are only 5:

5500 + 5520 Ce (= 5520 + 5500 eC)
5540 + 5560 Ce (= 5560 + 5540 eC)
5580 + 5600 Ce (= 5600 + 5580 eC)
5620 + 5640 Ce (= 5640 + 5620 eC)
5660 + 5680 Ce (= 5680 + 5660 eC)
5700 Ce unusable: 5700 + 20 MHz > 5710

Overlapped channels with previous list:
5500 eC unusable: 5500 - 20 MHz < 5490
5520 + 5540 Ce (= 5540 + 5520 eC)
5560 + 5580 Ce (= 5580 + 5560 eC)
5600 + 5620 Ce (= 5620 + 5600 eC)
5640 + 5660 Ce (= 5660 + 5640 eC)
5680 + 5700 Ce (= 5700 + 5680 eC)

With 60MHz channel (20+20+20 = Cee = eCe = eeC ), one channel are fully overlapped with the next or previous TWO!
Like previous example, the total unoverlapped combinations are only 3, LIKE 2,4GHz BAND!!!

5500 + 5520 + 5540
5560 + 5580 + 5600
5620 + 5640 + 5660
5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

With 80MHz channel (20+20+20+20 = Ceee = eCee = eeCe = eeeC ), one channel are fully overlapped with the next or previous THREE!
Like previous example, the total unoverlapped combinations are only 2:

5500 + 5520 + 5540 + 5560
5580 + 5600 + 5620 + 5640
5660 + 5680 + 5700 + xxx unusable: 5700 + 20 MHz > 5710

and if you see the "ac" standard, it can use also 160MHz channels. only one channel available:
5500 + 5520 + 5540 + 5560 + 5580 + 5600 + 5620 + 5640 Ceeeeeee ...... eeeeeeeC
5660 + 5680 + 5700 + xxxx + xxxx + xxxx + xxxx + xxxx unusable: 5700 + 20 MHz > 5710


This demonstrate how 802.11ac make previous unoverlapped 5GHz band,
full overlapped and unusable band worst than 2,4GHz band.
agree, and the things can be worst:

In wlan environment many 5ghz devices do not support DFS channels.

That leaves you only with 8 20 mhz channels 34-40-44-48 149-153-157-161 that is 4 40 mhz channels or 2 80mhz channels.

To avoid co-channel interference and do channel reuse you need minimum 4 non overlapping channels that leaves you limited to 40mhz channels.

Big distance From Marketing to reality on 5ghz

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