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bfg-9000
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Re: Tool to analyze WiFi hotspots

Sun Dec 04, 2016 1:52 am

Yep, each antenna/radio actually transmits on all of the selected channels at once, which is why just one antenna on Wave 2 should theoretically move "up to" 867Mbps--great considering most phones/tablets only have one.  Unfortunately it's not as simple as that.

At 5GHz the problem isn't usually one of interference but signal strength: 5/6 64-QAM Wireless-N requires a minimum -64dB signal for maximum data rate at 20MHz, dropping to -61dB for 40MHz.  3/4 256-QAM Wireless-AC requires -59dB at 20MHz, -56dB at 40MHz, -52dB at 80MHz, and -48dB at 160MHz so you can see it's only good for a very short distance before it drops to 64-QAM and throughput drops 33%.  In fact 160MHz/80MHz needs -62dB/64dB or they will drop all the way to 16-QAM. So basically at any reasonable distance AC is pretty much just about like N extended to 80MHz or 160MHz wide.  Worse, each additional antenna gives rapidly diminishing returns because after all, they are broadcasting on the same channels.

All of these numbers would actually be useful if you could trust the numbers those utilities show...
 
churin
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Re: Tool to analyze WiFi hotspots

Sun Dec 04, 2016 1:07 pm

Let me repeat  my question which started this discussion:
churin wrote wrote:
One question about Acrylic WiFi Home:  Channel # for 5GHz of my hot spot is supposed to be 149 but is shown as "149+153+157+161".  I wonder why.

Other tools show only 149, and channel of my neighbor's hot spots shown on all the tools is one channel each. Why multiple channels as above for my hot spot and not for my neighbor's? Is 153 one channel upper from 149?  Does my hot spot use four channels and my neighbor's only one?

I understand the idea that one should set hot spot channel to avoid interference from other hot spots.  I just picked 149 without knowing the spectrum condition. Now I am running WiFi tools and the above question is how to interpret what one of the tools indicates.
 
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Re: Tool to analyze WiFi hotspots

Sun Dec 04, 2016 3:43 pm

churin wrote:
Other tools show only 149, and channel of my neighbor's hot spots shown on all the tools is one channel each. Why multiple channels as above for my hot spot and not for my neighbor's? Is 153 one channel upper from 149?  Does my hot spot use four channels and my neighbor's only one?

It all depends on the channel width setting in the "Wireless Properties" section of whatever firmware you're using. If you set channel width to the minimum, it will only take up one channel. For each base unit you add to the width, you add another channel.
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churin
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Re: Tool to analyze WiFi hotspots

Sun Dec 04, 2016 7:05 pm

Wireless settings are as follows.  Only changes from the default settings are the control channels for 2.4GHz and 5.0GHz.  The channel bandwidths show multiple of bandwidths. What bandwidth(s) is/are used in this case?

 I read the manual for the first time but could not really understand how to select these options.  Comments on the WiFi settings as below are appreciated.
Image 
 
curtisb
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Re: Tool to analyze WiFi hotspots

Mon Dec 05, 2016 9:01 am

What I see in your screenshot is Control Channel and Extension Channel. I don't see "Primary" Channel. Without seeing the options available in the dropdown, I can only assume this would allow you to specify which way the channels are broadcast from the Control Channel--Above, which for 5GHz with a Control Channel of 149 would be 153 and higher, or Below, which would be 145 and below. I'm guessing at the dropdown options because of how you have the 2.4GHz channel set to Above. So what are the options for the following:

  • Wireless Mode for 2.4GHz and 5GHz?
  • Channel bandwidth for 2.4GHz and 5GHz?
  • Extension Channel for 2.4GHz and 5GHz?

On your Wireless Mode you're probably going to have (for 2.4GHz) something like Auto, b/g/n, g/n, n-only or something like that. I would recommend setting it to g/n and not broadcasting for 802.11b devices. Unless you have some really old devices, I doubt you have anything that operates on 11b. It might not be a bad idea to limit 11g to only operating on the 2.4GHz radio, too (set the 5GHz to a/n/ac or even just n/ac...I also doubt you have any devices that are 11a only).

With regards to why your AP shows up on four channels, but your neighbors' only show one channel...that could just be a configuration thing, difference in the age of the AP's, or even just a difference in class of AP.
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churin
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Re: Tool to analyze WiFi hotspots

Mon Dec 05, 2016 12:59 pm

Thanks for the detailed explanations.  Answers to the questions are as follows. The screen shots are placed here.  Further suggestion is appreciated.

2.4GHz
Wireless Mode: Auto, N only, Legacy
Channel Bandwidth: 20/40MHz, 20MHz, 40MHz
Extension Channel: Above, Below
5.0GHz
Wireless Mode: Auto, N only, N/AC mixed, Legacy
Channel bandwidth: 20/40/80MHz, 20MHz, 40MHz, 80MHz
Extension Channel: Auto
 
churin
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Re: Tool to analyze WiFi hotspots

Mon Dec 05, 2016 2:45 pm

The signal strength of 5GHz channel is about -15dbm but from time to time it dropps to -50dbm for short duration. But the guest account(5GHz) signal is stable at around -15dbm as shown on the following snap shot of Acrylic. I wonder why?  Note the two top traces(light green and purple) are the signal levels of my AP.
Image
 
curtisb
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Re: Tool to analyze WiFi hotspots

Tue Dec 06, 2016 1:18 pm

Your settings all look fine. The only thing I might change is to set the 5GHz channel to N/AC Mixed mode. This will force any 11g only devices over to the 2.4GHz radio.

With regards to the signal dips, that's just wireless for you. It's susceptible to interference from all kinds of things in the environment, and not just other AP's around it. You must be sitting almost literally right next to the radio to get -15db, though. I'm sitting about 30' away from an AP at work right now and getting -50db on 5GHz on my phone. I just stood under the AP and got -34db holding the phone up to within 4' of the AP.
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churin
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Re: Tool to analyze WiFi hotspots

Tue Dec 06, 2016 10:34 pm

My many thanks to  Curtisb and everyone. I have learned how to survey WiFi environment and to set AP options of my router.
Thank you so very much again.
 
Jaketech
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Re: Tool to analyze WiFi hotspots

Wed Apr 05, 2017 10:07 pm

Yan wrote:
What OS? For Windows, InSSIDer.

Version 2 of InSSIDer showed hidden networks. The capability was later removed. It's not difficult to find that version if you want it.

Edit: Oh, you did say Windows 10.


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