Low Wi-Fi throughput

[Arend van Spriel]

On 12/16/2013 11:28 AM, Arend van Spriel wrote:
> On 12/16/2013 11:16 AM, Alban JEANTHEAU wrote:
>> 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?
> 
> I guess you mean bit 32. It is set because you have 40 MHz.
> 
>  What MCS tx params is? Only one stream in Tx?
> 
> /* 802.11n HT capability MSC set */
> #define IEEE80211_HT_MCS_RX_HIGHEST_MASK	0x3ff
> #define IEEE80211_HT_MCS_TX_DEFINED		0x01
> #define IEEE80211_HT_MCS_TX_RX_DIFF		0x02
> /* value 0 == 1 stream etc */
> #define IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK	0x0C
> #define IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT	2
> #define		IEEE80211_HT_MCS_TX_MAX_STREAMS	4
> #define IEEE80211_HT_MCS_TX_UNEQUAL_MODULATION	0x10
> 
> So indeed it seems only one tx stream.

Correction: the comment seems to suggest you have two tx streams.

> Gr. AvS
> 
>> 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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> 
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