Has RRM an influence on clients connection quality?

[patoberli]

Hello

I tweaked on my controllers a few RRM parameters listed under Coverage Hole Algorithm.

Also under TPC a few parameters. There I changed the Transmitted Power Threshold to -72 and the Minimum Power Assignment to 8.

Also I updated the controller firmware (WiSM) from 7.0.240.3 to 7.0.250.0.

Since that (and the required reboots) some Windows 7 clients (not sure if Windows 8 is also affected, we don't yet have many) with Intel adapters and drivers from 2011 - 2012 started to act with short disconnects. Could those parameter changes be the reason for that or maybe the software upgrade?

The driver update usually fixes the issues, but I wonder where they actually come from.

Thanks

Patrick

[Leo Laohoo]

See what happens if you disable 802.11n.

If you disable 802.11n and everything goes good, then it's the drivers of the wireless NIC.

[Scott Fella]

Well the question is... Was it working fine before the change.  Setting the min TX power is fine as that prevents power from getting set to low, but CHD, I usually will not tweak. Tweaking parameters mean that you also understand your ap placement and how your RF is. Making changes can make coverage issue or even create too much channel overlap.  CHD can also make RRM calculate too often and make your environment pretty unstable.  The code upgrade to v7.0.250.0 is a good move, but maybe look at what tweaks you have done if after you made changes, clients started getting affected. 

[patoberli]

I can't really disable 802.11n, as my users depend on the speed. Maybe in a worst case I would try that.

It wasn't perfect before the update/changes, but nearly all client issues were on Windows 8. Now they started also on W7.

On CHD I changed the Coverage Level and Data RSSI, in the hope to get earlier alarms of when the signal might be to weak somewhere to support stable 802.11n speeds. So if there was a change, then the signal might be a tad stronger for the clients, but that should be a good thing. On TPC I actually made it a bit more sensitive to lower the signal strength.

[Scott Fella]

Thresholds are for alerts and don't affect anything... Enabling CHD changes the RF especially when people walk away from the building.  If your having issues, then you need to look at what the issue is with these clients.  It may come down to driver issues.  AP and Client will negotiate their rates so there is no need to worry here.... if they can't modulate at 802.11n rates or any specific rates, they will down shift to a lower rate.  Tweaking the environment only really works well when you have a dense AP deployment, which includes AP's in rooms, not just hallway's.

[patoberli]

It is a fairly dense network, designed that the client always has at least -70 dBI signal.

I also had the problem with the AP around 50 cm besides the client, the next AP around 20 meters further away, in a different room. So there is something weird.

I also have the feeling that the roaming takes much longer as it used to have. Maybe there is somewhere an issue with roaming, but I didn't change anything (besides the software upgrade).

[Scott Fella]

You need to tweak your data rates and max and min TX power.... The other stuff you can leave alone.

[Abhishek Abhishek]

Please refer to the link-

http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/71113-rrm-new.html