wlan blocked by scanning with WLanMgntClient

[paipeng]

I am trying to scan the available Wlan APs with their signal strengthes every 10 seconds by using the SDK Plugin WLanMgntClient.

But I found out, that my device's wlan will be blocked after some time. My program is blocked by the scan-point, the on-board wlan-scan doesn't work, ether. web browser not work (blocked at connecting to access point dialog).


I would like to ask, if somebody has the same problem like me by scanning the wlan aps?!!

I am using Nokia N95 with the original firmware on it.


SDK 3rd FP1 and the newst Open C


Thanks.

Pai

[omarfr]

Hi,

Indeed there is a problem with the WLAN Info API. I am troubble shooting it for 4 days now. I didn't find a solution yet.

I am using this code:

/**
 * Constants for XML representation
 */
_LIT(KXMLWNETTag, "<Network id=\"%d\">");
_LIT(KXMLWNETEndTag, "</Network>");
_LIT(KXMLWLANSecurityTag, "<Security>");
_LIT(KXMLWLANSecurityEndTag, "</Security>");
_LIT(KXMLWLANTypeTag, "<WLANType>");
_LIT(KXMLWLANTypeEndTag, "</WLANType>");
_LIT(KXMLBSSIDTag, "<BSSID>");
_LIT(KXMLBSSIDEndTag, "</BSSID>");
_LIT(KXMLSSIDTag, "<SSID>");
_LIT(KXMLSSIDEndTag, "</SSID>");
_LIT(KXMLWLANStrengthTag, "<WLANStrength>");
_LIT(KXMLWLANStrengthEndTag, "</WLANStrength>");

void CWLANInfo::GetWLANInfo(TDes &infoBuff)
{
	infoBuff.Zero();
	if(iWLANMgmtClient == NULL || iScanInfo == NULL)
		return;
	
	TInt securityMode;
	TInt i=1, k;
	TBuf<36> bss;

	_LIT(KOPEN, "Open");
	_LIT(KWEP, "WEP");
	_LIT(K802, "802d1x");
	_LIT(KWPA, "WPA");
	_LIT(KINFRA, "Infrastructure");
	_LIT(KADHOC, "Ad-hoc");
	_LIT(KBSSIDFormat, "%02X:");
	_LIT(KSSIDUnknown, "SSID Unknown");

	for(iScanInfo->First(); !iScanInfo->IsDone(); iScanInfo->Next() )
	{
		infoBuff.AppendFormat(KXMLWNETTag, i);
		i++;
		
		infoBuff.Append(KXMLWLANSecurityTag);
		securityMode=iScanInfo->SecurityMode();
		if(securityMode==EwlanConnectionSecurityOpen)
			infoBuff.Append(KOPEN);

		else if(securityMode==EwlanConnectionSecurityWep)
			infoBuff.Append(KWEP);
		else if(securityMode==EwlanConnectionSecurity802d1x)
			infoBuff.Append(K802);
		else if(securityMode==EwlanConnectionSecurityWpa)
			infoBuff.Append(KWPA);
		infoBuff.Append(KXMLWLANSecurityEndTag);

		//In general if the least significant bit of the capbility field 
		//is 1 then the network is of "Infrastructure Type" or else if the 
		//capability field is 0 then the network is of "Ad-hoc type"
		infoBuff.Append(KXMLWLANTypeTag);
		TUint16 capability=iScanInfo->Capability();
		TInt pad(1);
		TInt lanType=capability & pad;

		if(lanType==1)
			infoBuff.Append(KINFRA);
		else
			infoBuff.Append(KADHOC);
		infoBuff.Append(KXMLWLANTypeEndTag);
		
		infoBuff.Append(KXMLBSSIDTag);
		//Retrieve BSSID
		TWlanBssid bssid;
		iScanInfo->Bssid( bssid );
		bss.Zero();
		for(k = 0; k < bssid.Length(); k++)
			bss.AppendFormat(KBSSIDFormat, bssid[k]);
		//remove last :
		bss.Delete(bss.Length()-1, 1);
		infoBuff.Append(bss);
		infoBuff.Append(KXMLBSSIDEndTag);		
		
		infoBuff.Append(KXMLWLANStrengthTag);
		//Get transmision level
		TInt8 rxLevel = iScanInfo->RXLevel();
		infoBuff.AppendNum(rxLevel);
		infoBuff.Append(KXMLWLANStrengthEndTag);
		
		infoBuff.Append(KXMLWNETEndTag);
	}
}

The line in red is ok, I mean that WLAN Info API retrieves the information without problems, but the problem is in this code somewhere as my phone crashes randomly but always. I mean that it doesn't crash everytime I use the function, but only sometimes. Anyway, if I try to call the function for lets say 10 times it surely crashes. Sometimes it just crashes (without any error) and sometimes the phone gets restarted. I am using Nokia N95.

paipeng, are you using aprox. the same code as me?

If someone knows what is the problem please advice, it would be very helpful. Also... as I posted before, the guys from Nokia forgot to put a Cancel routing for the asynchronous version of GetScanResults.

If I discover the problem I'll say.

Thanks,
Omar

[paipeng]

yes, i am using the similar codes.


I am using RConnectionMonitor to get the signalstrength of connected AP during period the WLan scan.

And I think, the problem is on RConnectionMonitor and WLanMgntClient together.

Because when i don't use RConnectionMonitor, it looks like the wlan module on device doesn't block any more.

[omarfr]

I thought the same thing at first because I was also using RConnectionMonitor, but then I removed the RConnectionMonitor from my code and I still got the crash. The problem is from WLAN Info API, RConnectionMonitor works great. Only with RConnectionMonitor the application works fine but I don't have the BSSID info.

To get signal strenght you don't need RConnectionMonitor, you can get the strenght with WLAN Info API too.

It would be nice to know how to get BSSID with RConnectionMonitor as it behaves much better than WLANInfo API.

[paipeng]

With RConnectionMonitor blocks the wlan scan also after a random time.


Has anybody the same problem by wlan scanning under Symbian 3rd Edition?

Thanks

Pai

[bytes]

I'm using RConnectionMonitor for scannig. I didn't have any blocking problem.

[paipeng]

I'm using RConnectionMonitor for scannig. I didn't have any blocking problem.

How long do you set the scan interval?

I set it to 10-15 seconds.