I am using Wireless to connect to the internet (router). My laptop has Atheros wireless (AR 242x/542x) adapter but the router is a little bit far-away from my room so I have to use an external wireless adapter i.e. Alfa (Realtek 8187) for connectivity.

However, since I have started using Ubuntu I noticed that Alfa is not working in full power, internet speed in Ubuntu is much slower than in Windows on my laptop.

When I am using Windows 7 the LED (bulb) on Alfa blinks as it should, but when in Ubuntu, it doesn't blink rather it is on but very dim. Connection using Atheros adapter is also the same (slow)...

I have tried 4 methods (I found on the Internet) to troubleshoot this matter but no success. It seems to me that Ubuntu/Linux is not letting these wireless adapters to operate in full strength. iwconfig shows that power management is off for both.

So what's the problem?

Details:

ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1f:16:1e:36:ec  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:45 Base address:0x6000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:1657 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1657 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:241697 (241.6 KB)  TX bytes:241697 (241.6 KB)

wlan0     Link encap:Ethernet  HWaddr 00:22:5f:9b:24:b5  
          inet6 addr: fe80::222:5fff:fe9b:24b5/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:715460 errors:0 dropped:0 overruns:0 frame:0
          TX packets:694246 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:493539292 (493.5 MB)  TX bytes:235159393 (235.1 MB)

wlan1     Link encap:Ethernet  HWaddr 00:c0:ca:42:14:62  
          inet addr:192.168.100.102  Bcast:192.168.100.255  Mask:255.255.255.0
          inet6 addr: fe80::2c0:caff:fe42:1462/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:171053 errors:0 dropped:0 overruns:0 frame:0
          TX packets:181363 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:74094659 (74.0 MB)  TX bytes:59474204 (59.4 MB)

iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

wlan0     IEEE 802.11bg  ESSID:off/any  
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off

wlan1     IEEE 802.11bg  ESSID:"Zia"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 00:0D:F0:9C:A6:18   
          Bit Rate=54 Mb/s   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=70/70  Signal level=-31 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:204  Invalid misc:6610   Missed beacon:0