Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Confusion over the channel number

  1. #1
    Shocker_33 Guest

    Default Confusion over the channel number

    metageek forums
    Last edited by Shocker_33; 11-24-2017 at 02:02 PM.

  2. #2

    Default

    The "3 + 7" does mean the access point is on both channels. How is it possible? 802.11N APs use a 40MHz channel-bonding mode to achieve faster speeds. Normal 802.11G APs use a 20 MHz channel, so with channel bonding it uses 2 channels together to get better throughput. So in your case of 3 + 7, that means the primary (beacon/802.11g compatibility) channel is channel 3 and the secondary channel is channel 7.

  3. #3

    Default

    Thanks!
    Normally, all WiFi devices communicating with a single AP will communicate at the slowest speed supported by all connected devices. If all connected/active devices support 11n, then 11n will be used. However if all but one device supports 11n, and that one only supports 11g, all devices will communicate at 11g speeds. I don't know how to verify what mode is being used in Windows, but you can use the above as a rule of thumb.

  4. #4

    Default Tech support says two channels not possible

    Thanks for the explanation of how 802.11N uses two 20Mhz channels via channel bonding, Tyler. So, when I look at the signal from my Netgear WNR1000 router, I see it transmitting on both channels 1 and 5, which makes sense since it's an "N" router.

    Last month, I added an SR300 repeater from Amped Wireless to repeat the signal from the Netgear in hopes of boosting the range. As is normal, I've read, the repeater is also transmitting on both channels 1 and 5 as shown via inSSIDer.

    Not being very satisfied with the coverage of the Amped repeater (which runs 100mW and has two, 3.1dbi external antennas to boot), I just called Amped's tech support and spoke with Andrew. He told me that their repeater does NOT operate on two channels, only 1!. Even when I mentioned what I had learned here about 802.11N using two channels, he refused to change his mind.

    My reading is that Andrew is in need of some education regarding how "N" works. Would you agree, or have I missed something important in understanding why inSSIDer displays channels 1+5 for both my Netgear and the Amped repeater?

  5. Default

    Not all 11n hardware use bonded channels. But I think if it is broadcasting beacons saying it has bonded channels I think there is a high probability it is doing bonded channels.

    In reality, it is pretty rare that Wi-Fi actually uses bonded channels in the 2.4 GHz. inSSIDer is merely showing what it is capable of doing.

  6. #6

    Default

    Thanks for your reply, Trent.
    A follow up question comes to mind. If bonded channel use is rare on 2.4GHz and not all 11n hardware uses bonded channels, how is 11n able to produce faster speeds than 11g, something that is touted by hardware manufacturers of 11n products?

  7. #7

    Default

    After some research, I believe I can now answer my own question.
    Aside from channel-bonding, 11n can utilize spatial division multiplexing (SDM) known generally as MIMO (multiple-input multiple-output) for multiple, independent data streams (up to a max. of four) as long as separate transmit and receive antennas are involved. Then, on top of MIMO, channel bonding using two, 20Mhz channels (40Mhz) can also be used by 11n.
    I now understand that not much channel-bonding goes on at 2.4Ghz due to QRM (interference from other 802.11 signals or non- 802 systems like BlueTooth also using 2.4 Ghz.)
    Meanwhile, the 5Ghz band is large and uncrowded and therefore a better place for 40Mhz channel-bonding under 11n.
    Now I need to find out a little more about the beacon signals you mentioned Trent

  8. #8

    Default

    Quote Originally Posted by Tyler View Post
    Thanks!
    Normally, all WiFi devices communicating with a single AP will communicate at the slowest speed supported by all connected devices. If all connected/active devices support 11n, then 11n will be used. However if all but one device supports 11n, and that one only supports 11g, all devices will communicate at 11g speeds.
    Can I just double check I've understood that correctly. I have an HG532 router spec 802.11 b/g/n which is putting out around 40Mbps (upgrading to 80Mbps shortly). There are numerous n rated laptops wifi connected, but there are also occasionally g rated android phones and old g rated XP laptop. Are you saying when the phones connect the speed of everything else is brought down, so the router effectively becomes only b/g rated? And is that only while the phones are connected or any time after they have made a connection until their lease expires or the router is rebooted?

  9. #9

    Default

    Alexi,

    Think of b/g/n as different languages (just as an analogy). So you have devices which are speaking n language with the router, but suddenly, devices that speak only g language connect, so the router has to speak g to those devices as n is backwards compatible with g, so all devices are now stuck speaking g because the other devices can only understand g.

    So in short, yes, having g devices connected to the modem can slow down your n devices because the modem gets stuck speaking in g.

    I hope that helps

    Stephen

  10. #10

    Default

    "can" being the operative word... (slow down devices)

    However, this simply isn't true any more for modern devices/routers capable of "mixed-mode" operation that can run 11b+11g+11n simultaneously (Vigor 2820Vn is one example - there are others) without impacting each other at all using multiple radios & data streams.

    I'm sitting here just now running "n" on this laptop connected at a max data rate of 300Mbps, an older laptop running "g" (54Mbps), an Android smartphone running "g" and an old PocketPC running "b". If I run data rate tests on them all at the same time from a wired in connection to my router (another PC), the stream rates reflect exactly what I would expect of each connection and its bit rate and not your assertion that they all come down to the lowest common denominator; in this case, the speed of 802.11b.... (the max overall speed shown by inSSIDer for the 2820 is 450Mbps)
    Last edited by CPN; 03-22-2012 at 03:59 PM.

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •