Dropping wifi connectioin on broadcom BCM4312

rshuman222 · 03-28-2014, 06:52 AM

I am having difficulties with keeping a reliable connection to my wifi hotspot on my dell laptop.
Sometimes, the connection is very stable and runs at a decent speed; at other times, it constantly drops (sometimes within a few minutes, other times every 5 seconds, etc.). Also, whenever it drops, the ping latencies become very high (>10000ms). I'm using a broadcom BCM4312 with the b43 driver on debian stable (with latest package updates).
I've noticed the following:
- It is very unlikely the problem is related to signal strength. The averge strength is >-25dBm, and even with the hotspot next to the laptop the problem persists. None of my roommates seem to experience the issues I have. Also, this happens at public hotspots as well.
- The problem doesn't seem to occur in WinXP
- I've tried the "qos=0 pio=1" options in the b43 module, without any noticeable difference
- I've noticed that if I keep the connection "busy" (e.g. by constantly sending ping requests), the connection drops less often.
- I tried both wicd and wpa_supplicant with custom config to connecto to the network. I noticed that every time I reconnect with wicd, the firmware is reloaded (which freezes the computer for a few seconds). dmesg output is as follows:

Code:

[  565.676485] b43-phy0: Loading firmware version 478.104 (2008-07-01 00:50:23)
[  571.229289] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[  606.797102] wlan0: authenticate with ---masked------- (try 1)
[  606.996108] wlan0: authenticate with ---masked------- (try 2)
[  607.196293] wlan0: authenticate with ---masked------- (try 3)
[  607.286437] wlan0: authenticated
[  607.287554] wlan0: associate with ---masked------- (try 1)
[  607.320205] wlan0: RX AssocResp from ---masked------- (capab=0x411 status=0 aid=1)
[  607.320215] wlan0: associated
[  607.321703] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[  607.321813] cfg80211: Calling CRDA for country: CN
[  607.332149] cfg80211: Regulatory domain changed to country: CN
[  607.332157] cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[  607.332165] cfg80211:     (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[  607.332173] cfg80211:     (5735000 KHz - 5835000 KHz @ 40000 KHz), (N/A, 3000 mBm)
[  609.162399] wlan0: deauthenticating from ---masked------- by local choice (reason=3)
[  609.192691] cfg80211: Calling CRDA to update world regulatory domain
[  609.202781] cfg80211: World regulatory domain updated:
[  609.202789] cfg80211:     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
[  609.202798] cfg80211:     (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[  609.202806] cfg80211:     (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[  609.202814] cfg80211:     (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
[  609.202821] cfg80211:     (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
[  609.202829] cfg80211:     (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)

I'm not in China, but I don't see how to set that option. Could that be the source of the problem? The firmware itself was extracted with b43-fwcutter (I've tried multiple versions of the broadcom driver to extract from, with little to no difference)

I've noticed there are a lot of topics on related issues (all kind of similar broadcom pci cards). All of them were pre-2011 and none of them described any solution to my problem. I'm really desperate; any help/remark is welcome! My only guess would be that it is a firmware related issue? If no software solution is possible, do you guys think that a cheap Atheros wifi card of ebay (which seem to have open firmware) would mitigate the problem?

Thanks in advance!

business_kid · 03-28-2014, 02:29 PM

I have one, and find it reliable. You need the correct(not the latest) version of the fwcutter thing and the correct version of the software to cut from, which is a major pain.

That done, It's ok -25dBm is 1 milliwatt multiplied by 1/316 = 3.16uW or 3x10^-6 watts, which is not a great signal.
I check the levels with the Quality factor in

Code:

 iwlist wlan0 scan

it also helps to be 6 channels away from your nearest neighbours as wifi uses several channels if it can to make your speed faster. Each one uses about 5 channels. This is the sort of thing you learn staying awake through classes in College

Quote:

Now I lay me down to sleep;
The speaker's dull, the subject deep.
If he stops before I wake,
Give me a nudge, for heaven's sake!

rshuman222 · 03-28-2014, 02:58 PM

Well, I figured out how to change the 802.11 region code, let's see if that helps.
Can I ask what firmware version you use?

À propos, I believe your signal deduction is wrong: -25dBm is a great signal strength. Mind that this is the receiving end (which is always weak), and does not incorporate any information on the noise floor at all.
I'm still pretty sure the problem is related to the laptop, and not the hotspot.

business_kid · 03-29-2014, 04:55 AM

The box says it's loading version 478.104 (2008-07-01). Mind you, it is running a rather dated 3.2.29 kernel. It's the original version from somewhere (Slackware-13.1?), and I never bothered updating it.