problem with configuring 40mhz width channel on Aironet 1141

[Temur Kalandia]

hello,

      recently we purchased cisco aironet AIR-AP1141N-E-K9 standalone model.  after configuring it , client has no problem with connection and coverage, but there is problem with thoughput.  clients are not able to connect at higher rates, even if i set channel width at 40 mhz, max rate for N capable client device is 54mb.

      can someone give me a little hints  how to solve this problem?

this is my configuration , or see attached file

http://pastebin.com/1WHeSvmq

many thanks

[art-barrera · Accepted solution]

Please change the encryption used to AES.

Here is more information: http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080a3443f.shtml

Thx //art

[Temur Kalandia]

hello,

thank you very much..    changed encryption to  ciphers aes-ccm and achieved 144mb physical rates..    

the real traffic was about 35-40mb/ps.

what is max rate i can reach on this AP?  form the data sheet : PHY data rates up to 300 Mbps,

  http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10092/datasheet_c78-502793.pdf

is this real?

regards

[Leo Laohoo]

You sure that your WAP's model number is an 1141 instead of an 1142?

If your WAP's model number is 1141 (instead of 1142), then you can't configure 40 Mhz and 802.11n because your WAP only has 802.11b radio, hence ends with a "1". 

[Temur Kalandia]

hello, 

we've bought exaclty this model :

● AIR-AP1141N-x-K9 - Single-band Standalone 802.11g/n (see data sheet:

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10092/datasheet_c78-502793.pdf   )

       I can set the 40 mhz channel width , but max rate i achieved is 144Mbps (it is 20MHz, GI=400ns).  if it would be 40MHz, GI=400ns  i will achieve 300Mbps, but channel width still remains 20MHZ.

[art-barrera]

Good catch leo....actually, VERY important catch!

First, understand that 802.11n supports both 2.4Ghz and 5Ghz bands...together, seperate whatever combination you choose.  Your access point only has a single radio operating in the 2.4Ghz band so you will be running 802.11n on the 2.4GHz band.  This will limit you to channels 1 - 11 given that 1,6 and 11 are the only non-overlapping channels in the band.  Technically you can create a single 40MHz channel but it's not advised with those channels but it's not advised.  We already have enough of a challenge managing CCI using the 3 channels and I would suspect that your returns on gaining a 300Mbps PHYrate would really result in poor movement of data and a poor MCS 11n rate.

I actually seem to remember that by a certain date, manufacturers were not going to allow the use of 40MHz channels in the 2.4GHz band.....i'd have to look  back to confirm so I'm not sure.  Basically - Good practice is to not enable 40MHz channels in 2.4Ghz spectrum.

For your radio, disable all non OFDM data rates, use WPA2/AES, make WMM available, enable High Throughput 11n and stay at 20MHz channels.  Connect your station to the network and look at the client details.  In the client details you will see the reported MCS rate negotiated for that connection.  That will translate to number of streams allowed, data rate etc.  Just google MCS data rate and you can find the 11n table of MCS definitions.

Although the following guide is specific for high density education environments, it really does a good job of explaining how to plan your RF environment.  www.cisco.com/web/strategy/docs/.../cisco_wlan_design_guide.pdf

Hope this helps and not confuse.

//art

[Roger Alderman]

Not quite sure what you perceive to be the problem here.

The correct answer was to switch from TKIP to AES in order to enable the highere data rates.

The AP will provide up to 300Mbps physical data rate but the maximum effective data rate is only going to be around 144Mbps and you are very reliant on the client adaptor card supporting 2 spatial streams.

Everything would have to be perfect to achieve the highest data rates so if you are achieving in excess of 100Mbps you're doing very well.

[Temur Kalandia]

many thank to everyone  

      But , i have single AP ,  i know that there will be channel overlaping with 40MHZ channel width at 2.4ghz band, but there is not any AP to overlap with.....So  i still need to achieve high speeds at least 80-100Mbps (i mean real speed  not PHY rate).   At this moment i have about 35 Mbps actual speed (phy rate is about 144mbps  MSC15 ) 

please give me little hints to enable this function

[Scott Fella]

I only knew of the 1252 autonomous image that initially allowed 40mhz on the 2.4ghz. Cisco eventually removed that option. If your only able to set 20mhz, then your stuck at the speed you are getting. Even if your seeing 144mbps, wireless is half duplex so your only going to transmit or send at half of that which is around 72mbps. The more users that are connecting the lower the actual throughput you will see. If its your only AP, I would try to disable any of the 802.11b rates, set 24mbps or higher data rate as mandatory and see what speeds you see.

Sent from Cisco Technical Support iPhone App

[Temur Kalandia]

     undarstand but, there is an option in the radio interface and i can set channel width to 40MHZ.....i have olready done this but it doesn't works.

So does this means that we can set 40Mhz option , but actually it will not work?   is it fake command?  if so why data sheet shows that max PHy is 300ps

[Leo Laohoo]

undarstand but, there is an option in the radio interface and i can set channel width to 40MHZ.....i have olready done this  but it doesn't works.

I don't think you do understand this.

Let's get things straight here.  If you want to do channel bonding to 40 Mhz, you need 802.11a radio.  You CANNOT do a channel bond on the 802.11b radio because it doesn't make any logical sense.  The only group of people who'll say you CAN bond 40 Mhz with 802.11b are the sales people.

So even if you can configure your 802.11b to "operate" at 802.11n, you won't get full 802.11n data rates. 

[art-barrera]

I'm new to this community but I have a new "love for Mr. leo

//art

[George Stefanick]

"leos head is growing" ... please dont feed the animals

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

[Scott Fella]

Oh nooooooo.... George I think its too late!

Thanks,

Scott

Help out other by using the rating system and marking answered questions as "Answered"

[Leo Laohoo]

LOL