My wireless internet speed is not stable with linux
 

I am a Linux newbie using fc11 and wireless broadband from 3G for my personal laptop. Sometimes my download speed is up to 100+ kB/s (due to my observation from using yum command) and also there is time its only 5.6 kB/s. Its really slow.
At first, I disabled automatic update so that it can work faster. It does work faster for a while and then the speed drops to around 11 or 12 kB/s. Its really not stable

I tried to google for several days to see if there is anything helping me in this matter but no such luck.

Any suggestion would greatly appreciated.

Thanks

Have you ruled out that the 3g connection as such is flakey?

Nope!
But anyway, when I disconnected the USB wireless broadband and plugged it back in, the speed seems to be ok. And it just lasted for only 1 hour and dropped the speed down to 11kB/s. Then I decided to chuck that wireless broadband and get another one to see if that wireless broadband is hardware faulty. Moreover, that wireless broadband of mine has been in use for 3 years so I think its time to replace it. And the new one works perfectly

Anyway, thanks for your time guys