[ltp] T400 slow wifi connections
Joerg Mayer
linux-thinkpad@linux-thinkpad.org
Tue, 17 Sep 2013 07:20:17 +0200
On Mon, Sep 16, 2013 at 04:28:23PM +0100, Paul Marwick wrote:
> >>The wifi card in the T400 is Intel PRO/Wireless 5100 AGN [Shiloh]
> >>Network Connection.
> >So the Windows througput should be very close to the therorectical
> >receive maximum for the 5100. Maximum transmit should be half that.
>
> That was one of the things that struck me - it looks as though my
> connect speeds are around half the maximum.
That's not what I wanted to say: If I read the specs correctly, the
card has a theorectial max write speed that is half of its theorectial
max read speed (1 transmit stream but 2 receive streams).
> >Can you please post the output of the following commands:
> >
> >iw reg get
>
> country GB: DFS-UNSET
> (2402 - 2482 @ 40), (N/A, 20)
> (5170 - 5250 @ 40), (N/A, 20)
> (5250 - 5330 @ 40), (N/A, 20), DFS
> (5490 - 5710 @ 40), (N/A, 27), DFS
> (57240 - 65880 @ 2160), (N/A, 40), NO-OUTDOOR
>
> >iw dev wlan0 info
>
> Interface wlan0
> ifindex 3
> wdev 0x1
> addr 00:1e:65:19:f9:be
> ssid ASUS_5G
> type managed
> wiphy 0
> channel 36 (5180 MHz), width: 40 MHz, center1: 5190 MHz
OK, so linux is using 40 MHz channels - I had expected to see only 20 MHz channels
here. There goes my main suspect.
> >iw dev wlan0 scan -u (only paste the data for your SSID)
>
> BSS 10:bf:48:3c:df:b0(on wlan0) -- associated
> TSF: 2266987624311 usec (26d, 05:43:07)
> freq: 5180
> beacon interval: 100 TUs
> capability: ESS Privacy (0x0011)
> signal: -35.00 dBm
> last seen: 93 ms ago
> Information elements from Probe Response frame:
> SSID: ASUS_5G
> Supported rates: 6.0* 9.0 12.0* 18.0 24.0* 36.0 48.0 54.0
> DS Parameter set: channel 36
> Unknown IE (60): 01 16 24 00
> HT capabilities:
> Capabilities: 0x1ee
> HT20/HT40
> SM Power Save disabled
> RX HT20 SGI
> RX HT40 SGI
> TX STBC
> RX STBC 1-stream
> Max AMSDU length: 3839 bytes
> No DSSS/CCK HT40
> Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
> Minimum RX AMPDU time spacing: 4 usec (0x05)
> HT RX MCS rate indexes supported: 0-23, 32
> HT TX MCS rate indexes are undefined
> HT operation:
> * primary channel: 36
> * secondary channel offset: above
> * STA channel width: any
> * RIFS: 0
> * HT protection: no
> * non-GF present: 0
> * OBSS non-GF present: 0
> * dual beacon: 0
> * dual CTS protection: 0
> * STBC beacon: 0
> * L-SIG TXOP Prot: 0
> * PCO active: 0
> * PCO phase: 0
> Secondary Channel Offset: no secondary (0)
> RSN: * Version: 1
> * Group cipher: CCMP
> * Pairwise ciphers: CCMP
> * Authentication suites: PSK
> * Capabilities: (0x0000)
> WMM: * Parameter version 1
> * BE: CW 15-1023, AIFSN 3
> * BK: CW 15-1023, AIFSN 7
> * VI: CW 7-15, AIFSN 2, TXOP 3008 usec
> * VO: CW 3-7, AIFSN 2, TXOP 1504 usec
> BSS Load:
> * station count: 0
> * channel utilisation: 1/255
> * available admission capacity: 31250 [*32us]
> Vendor specific: OUI 00:0c:43, data: 07 00 00 00
> Country: GB Environment: Indoor/Outdoor
> Channels [36 - 48] @ 16 dBm
>
Remaining ideas: On a (more or less freshly booted and associated system)
do:
dmesg | grep -E -i 'iwl|80211|wlan0'
to see the kernel messages about the wifi setup and association, maybe there
is something in there that catches the eye.
find /etc -iname *"iwl*"
To see whether there are any modprobe parameters that disable some things.
If that doesn't help, you'll probably have to look for support:
http://wireless.kernel.org/en/users/Support
Ciao
Jörg
--
Joerg Mayer <jmayer@loplof.de>
We are stuck with technology when what we really want is just stuff that
works. Some say that should read Microsoft instead of technology.