Low Wi-Fi throughput

Alban JEANTHEAU alban.jeantheau at jcp-consult.com
Mon Dec 16 05:16:54 EST 2013


Hi Antonio,

  Thank you for your answer. Please find my comments below:


*> why using WPA-NONE when you can use RSN ? WPA-NONE is not really WPA..>
How can you use CCMP with WPA-NONE?*

To be honest I didn't focus on key / ciphering configuration, and I copy an
existing configuration found somewhere. However
http://hostap.epitest.fi/gitweb/gitweb.cgi?p=hostap.git;a=blob_plain;f=wpa_supplicant/wpa_supplicant.conf
 states:
# mode: IEEE 802.11 operation mode

# 0 = infrastructure (Managed) mode, i.e., associate with an AP (default)
# 1 = IBSS (ad-hoc, peer-to-peer)
# 2 = AP (access point)
# Note: IBSS can only be used with key_mgmt NONE (plaintext and static WEP)
# and key_mgmt=WPA-NONE (fixed group key TKIP/CCMP). WPA-None requires
# following network block options:
# proto=WPA, key_mgmt=WPA-NONE, pairwise=NONE, group=TKIP (or CCMP, but not
# both), and psk must also be set.


*>     htmode=HT40-*

If I don't set htmode, I'm stuck with 54Mbps. If i set htmode=HT20, I
can use 72.2Mbps, if I set htmode=HT40- I can use 150Mbps. And you
guess right I am using openwrt, sorry for not mentionning it...

ht_capa file of my peer:

ht supported
cap: 0x02f2
    HT20/HT40
    Static SM Power Save
    RX Greenfield
    RX HT20 SGI
    RX HT40 SGI
    TX STBC
    RX STBC 2-streams
    Max AMSDU length: 3839 bytes
    No DSSS/CCK HT40
ampdu factor/density: 3/4
MCS mask: ff ff 00 00 01 00 00 00 00 00
MCS tx params: 7

I am not sure I understand everything here. Why bit 19 is set in MCS
mask? What MCS tx params is? Only one stream in Tx?


  Cheers

Alban




On Fri, Dec 13, 2013 at 6:11 PM, Antonio Quartulli
<antonio at meshcoding.com>wrote:

> Hi Alban,
>
> On 13/12/13 18:06, Alban JEANTHEAU wrote:
> > Hi every one,
> >
> >   I need to make Wi-Fi connections between my device and I require a
> > high throughput. I mainly target IBSS network. For IBSS, I'm using
> > wpa_supplicant with USB dongle Asus N53 (RT3572, here is my
> > configuration file:
> >
> > ap_scan=2
> > network={
> >     scan_ssid=1
> >     ssid="MySsid"
> >     frequency=5200
> >     mode=1
> >     key_mgmt=WPA-NONE
>
> why using WPA-NONE when you can use RSN ? WPA-NONE is not really WPA..
>
> >     proto=WPA
> >     psk="MyKey"
> >     pairwise=NONE
> >     group=CCMP
>
> How can you use CCMP with WPA-NONE?
>
> >     htmode=HT40-
>
> where have you seen this parameter? This is not supported by
> wpa_supplicant as it is nl80211 specific....and we didn't find a
> reasonable way to push into the configuration engine any driver-specific
> parameter.
>
> Are you using openwrt by any chance?
>
> > }
> >
> > The maximum throughput I can reach is about 22Mbps (iperf TCP between 2
> > devices 2 meters away).
>
> My guess is that the IBSS connection is not exploiting the HT
> capabilities. Please, look for a file called ht_capa in /sys/ (you
> should have one of this file for each peer you have) and check its content.
>
>
> Cheers,
>
>
> --
> Antonio Quartulli
>
>
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