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Opened 3 years ago

Last modified 22 months ago

#17849 new defect

Hard to get tx bitrate over 65Mbit/s in pair with Intel Advanced N 6235

Reported by: cra3y Owned by: developers
Priority: high Milestone: Barrier Breaker 14.07
Component: kernel Version: Barrier Breaker 14.07
Keywords: ath9k wifi speed tx bitrate 65Mbps Cc:

Description

Hello

I noticed strange behaviour of wifi driver (ath9k) on my TL-WR1043ND v1.8. TX bitrate (issued by command 'iw dev wlan0 station dump' and showed in Luci Wi-Fi Page) stayed very frequently on 65Mbit/s in pair with Intel Advanced N 6235 on my laptop (under Win 8.1).

It looks like that:
Station c8:f7:33:e5:b0:2d (on wlan0)

inactive time: 10 ms
rx bytes: 234064
rx packets: 1271
tx bytes: 1187713
tx packets: 1521
tx retries: 41
tx failed: 0
signal: -29 [-33, -41, -33] dBm
signal avg: -28 [-33, -41, -32] dBm
tx bitrate: 65.0 MBit/s MCS 7
rx bitrate: 130.0 MBit/s MCS 15
authorized: yes
authenticated: yes
preamble: long
WMM/WME: yes
MFP: no
TDLS peer: no

Sometimes (2 on 10 run of 'wifi' command) tx bitrate pass 65Mbit/s and stayed on 130Mbit/s for some time.

Also switched Power Save mode for wireless card using (under Win8.1) Control Panel -> Power Plan -> Power Saving mode betweend 'Maximum Performance' and 'Maximum Power Saving' always trigger switching from 65Mbit/s into 130Mbit/s. But after period of time its back to 65Mbit/s
http://theitbros.com/wp-content/uploads/2012/11/powerplan3.png

It doesn't matter how signal is strong (i tested with different power settings and laptop distance from TP-Link). Also I tested with second TL-WR1043ND v1.8 and got the same result.

I'm using r42464 trunk (Chaos Calmer), but the same was on Attitude Adjustment and Barrier Breaker. Only with Backfire (and Gargoyle 1.5.6) 'tx bitrate' was always correct.

Station c8:f7:33:e5:b0:2d (on wlan0)

inactive time: 10 ms
rx bytes: 626935
rx packets: 7503
tx bytes: 37796920
tx packets: 25609
tx retries: 255206
tx failed: 49
signal: -35 dBm
signal avg: -37 dBm
tx bitrate: 130.0 MBit/s MCS 15
rx bitrate: 130.0 MBit/s MCS 15

I tested my Intel Advanced N 6235 with UBNT UniFi and original TP Link and always got 130Mbit/s, so this is not windows driver issue nor wifi card issue.

logread and dmesg showed nothing interesting (zero messages like "DMA failed" etc.). Also disabling or enabling ANI changes nothing.

I could provide more information if You tell me, how to do.

Attachments (0)

Change History (8)

comment:1 Changed 3 years ago by cra3y

I forgot to mention that when tx bitrate is 65Mbit/s it is impossible to get over 42Mbit/s (download) in speed test, but when tx bitrate is 130Mbit/s i always got 80Mbit/s (ISP limit in my contract). So this is not "iw" command fault or issue.

comment:2 Changed 3 years ago by cra3y

I did some research and i found that is difference in reported capabilities (SM Power Save) between TL-WR1043ND and Intel Advanced N 6235.

This is from command 'iw phy0 info' for TL-WR1043ND

Capabilities: 0x104e

HT20/HT40
SM Power Save disabled
RX HT40 SGI
No RX STBC
Max AMSDU length: 3839 bytes
DSSS/CCK HT40

this is from command 'cat /sys/kernel/debug/ieee80211/phy0/netdev\:wlan0/stations/c8\:f7\:33\:e5\:b0\:2d/ht_capa' for Intel Advanced N 6235.
cap: 0x0000

HT20
Static SM Power Save
No RX STBC
Max AMSDU length: 3839 bytes
No DSSS/CCK HT40

ampdu factor/density: 3/5
MCS mask: ff ff 00 00 00 00 00 00 00 00
MCS tx params: 0

I borrowed different Wi-Fi card - Intel WiFi Link 5100 AGN and checked that this card always negotiated 130Mbit/s 'tx bitrate' ('rx bitate' will always be 65Mbit/s or lower, because of this card design)

Station 00:26:c6:17:e5:88 (on wlan0)

inactive time: 11800 ms
rx bytes: 750732
rx packets: 4629
tx bytes: 3119847
tx packets: 4087
tx retries: 112
tx failed: 2
signal: -37 [-46, -39, -43] dBm
signal avg: -37 [-45, -38, -43] dBm
tx bitrate: 130.0 MBit/s MCS 15
rx bitrate: 65.0 MBit/s MCS 7
authorized: yes
authenticated: yes
preamble: short
WMM/WME: yes
MFP: no
TDLS peer: no

so i checked this card capabilities:
ht supported
cap: 0x000c

HT20
SM Power Save disabled
No RX STBC
Max AMSDU length: 3839 bytes
No DSSS/CCK HT40

ampdu factor/density: 3/5
MCS mask: ff ff 00 00 00 00 00 00 00 00
MCS tx params: 0

and bingo?

So TP-Link hardware (with 'SM Power Save disabled') works well with Intel WiFi Link 5100 AGN ('SM Power Save disabled') but have a problem with Intel Advanced N 6235 ('Static SM Power Save').

I tried to disable Power Save for Intel Advanced N 6235, but there is no way int Win8.1 and driver's properties to do.

comment:3 Changed 3 years ago by cra3y

The last build (r42475) doesn't change anything. Still have to switch Wireless Adapter Settings -> Power Saving Mode from "Minimum Perfomance" to "Maximum Perfomance" or "Maximum Perfomance" to "Minimum Perfomance" to trigger to move 'tx bitrate' from 65Mbit/s to 130Mbit/s

comment:4 Changed 3 years ago by cra3y

Tested with r42655, still no difference.

comment:5 Changed 3 years ago by anonymous

In case of an upgrade from a previous openwrt-Version: Have you regenerated your /etc/config/wireless?

mv /etc/config/wireless /etc/config/wireless.bak
wifi detect > /etc/config/wireless
echo "# --old config --" >> /etc/config/wireless
cat /etc/config/wireless.bak >> /etc/config/wireless
vi /etc/config/wireless

[now delete unneeded parts of the old config like "list ht_capab ..." and only take over txpower and channel- move them to the upper section with pressing "d" "d" and pasting by "p" and "disabled from the new radio section as well as the OpenWRT-SSID-section and the comment]. [so you have a new, combined radio-section and old interfaces].

quit with ":" "x" "Enter"

Restart wifi

wifi down && wifi

Background: in BB14.07 the capabilities are now autodetected per device. Adding and removing is usually not necessary. You may have faulty values in your config.

comment:6 Changed 3 years ago by anonymous

Hi

I always regenerate whole config (I did it using luci or uci), also I tried to add capability to config by hand, but no results (You confirmed that in BB wifi capability is autodetected, so is not necessary to change it by hand).

Any sugestions?

PS: Please notice that this is a problem in tandem This router and this Intel card (6235), but no problem with older intel card.
Perhaps ath9k do mistake in detect 6235 capability and enable "Static SM Power Save" for this card and cause problem described in previous post.
My propose is to test customized openwrt build with "Static SM Power Save" disabled for wifi clients, could You? I will test and report.

comment:7 Changed 3 years ago by cra3y

Hi

I always regenerate whole config (I did it using luci or uci), also I tried to add capability to config by hand, but no results (You confirmed that in BB wifi capability is autodetected, so is not necessary to change it by hand).

Any sugestions?

PS: Please notice that this is a problem in tandem This router and this Intel card (6235), but no problem with older intel card.
Perhaps ath9k do mistake in detect 6235 capability and enable "Static SM Power Save" for this card and cause problem described in previous post.
My propose is to test customized openwrt build with "Static SM Power Save" disabled for wifi clients, could You? I will test and report.

comment:8 Changed 22 months ago by makedir

You need to change PCIE power saving, not Wifi Power Saving under Windows power settings.

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