Poor wifi performance after upgrading XBian with TP-LINK TL-WN823N (rtl8192cu)

Question

I'm on a RPi B+, with an USB Wifi adapter, TP-LINK TL-WN823N, wich uses a rtl8192cu chipset, and is a N adapter. I have also a TP-LINK N router.

I was using XBian 1.0RC3, and I recently upgraded; they switched to rolling updates, so I received a lot of new packages from the main Debian repo.

Since the update, the Wifi performance are greatly worsen:

• if I use the RPi with a few inch from the router, the performace is great, with ~72M rate and 70/70 signal quality
• if I use the RPi in my living room, where it was before, the wifi connection lags and sometimes goes down for a few seconds.

I used sudo iwconfig wlan0 rate 54M to force 11g connection, and it got better, but still I have some lag.

Current sudo iwconfig wlan0 output:

wlan0     IEEE 802.11bgn  ESSID:"Airbase"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: E8:94:F6:6A:DD:C4   
          Bit Rate=54 Mb/s   Tx-Power=20 dBm   
          Retry short limit:7   RTS thr=2347 B   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=54/70  Signal level=-56 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:20752   Missed beacon:0

As you can see, 54M rate is forced, and a lot of invalid packets are listed: Invalid misc:20752

QUESTION: What can I do to investigate and improve the connection? What should I look at, that could be changed by the upgrade?

Answer 1

I solved my issue updating my XBian (and Debian) packages (using xbian-config).

My network rate is now up to an astounding 144Mb\s!!! with 80/100 (+15%) of signal level and no invalid packages error or trasmission problem.