Because of your local areas regulations, the operating systems will limit the power and channels based your location rules.
Some locations in the world have no rules on power and channels.
If you want maximum power and channels do this:
sudo iw reg set BO
sudo iwconfig wlan1 txpower 30
Remember to heatsink the RTL8187 so it does not get fried by the power increase.
To check if the change was successful:
sudo iw reg get
You should see the BO region set.