TP-Link TL-WN8200ND works very slowly

Question

I run Ubuntu 12.04 on a PC, recently I purchased a TP-Link USB adapter TL-WN8200HD

As it turned out it is not supported by the drivers that came with the Ubuntu 12.04. From Web Search I understood that the core of this tp-link usb adapter is Realtek hardware and that suitable driver for Linux is 8192cu that can be found on the
Realtek web site. I downloaded it and followed the instructions on http://www.linux-hardware-guide.com/2013-04-21-tp-link-tl-wn823n-mini-wireless-n-usb-300mbps

Eventually my USB adapter works, it recognize my wireless network and even connects to internet. but the transition rates are very low.

when I connect by wire (Ethernet cable) i achieve around 10Mb download and 1Mb upload. while when I connecting wireless i get only 5Mb download and almost no upload (with 1m distance)

what can be the reason for that ?

If it can help, this is the result of iwconfig command :

wlan0   IEEE 802.11bg  ESSID:"naparniki10"  Nickname:"<WIFI@REALTEK>"
          Mode:Managed  Frequency:2.442 GHz  Access Point: 74:EA:3A:C3:A2:B8   
          Bit Rate:54 Mb/s   Sensitivity:0/0  
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=100/100  Signal level=100/100  Noise level=0/100
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

p.s : I am relatively new to Ubuntu (and Linux). so please be detailed in your response

Solution

TL-WN8200ND has RTL8192CU (Realtek) chipset (see here: https://wikidevi.com/wiki/TP-LINK_TL-WN8200ND)

You can download the Linux driver here: http://www.realtek.com/downloads/downloadsView.aspx?Langid=1&PNid=21&PFid=48&Level=5&Conn=4&DownTypeID=3&GetDown=false&Downloads=true#2772

Just unzip and run sudo bash install.sh inside the uncompressed directory.

It works OK for me under Debian Wheezy, I think it should work on Ubuntu also.