Enable wireless in Ubuntu 12.04
So, you installed Ubuntu 12.04 with high hopes and found that wireless is not working with message “firmware is missing”. You can google about it which will give shit load of links with all the unix commands and info. The basics is that this problem is with Broadcom wireless network cards and the kernel’s default module wl is not working with it. So, you have to install the b43 series drivers for it and disable the default drivers.
Just fire up the following commands on terminal:
sudo apt-get update
sudo apt-get install firmware-b43-installer
sudo apt-get remove bcmwl-kernel-source
and reboot. When you will go to System Settings -> Additional drivers, it will show you that you are using Broadcom STA proprietary wireless driver.