This tip probably trivial, but if you have problems in wifi connection to WAP (Wireless Access Point) using Lenovo G480 laptop, then probably this tip should make your laptop sane. Note that wifi configuration has been successfully identified at install time and modules perfectly loaded without user intervention using brcmsmac and its dependencies. The problem is on the result of this driver. In my laptop, I found that wifi connection is very unstable.
I went to Arch Linux wiki and AUR (as always), then checked the https://wiki.archlinux.org/index.php/Broadcom_wireless page, then I realized that this unstable connection problem came from the driver. So I tried broadcom-wl driver from AUR. Just do this:
# yaourt -S broadcom-wl
and wifi connection work very stable after the next reboot without configuration. This package put a configuration file at /etc/modprobe.d/broadcom-wl.conf. It consists of:
$ cat /etc/modprobe.d/broadcom-wl.conf
Note: If you don't use Arch Linux, grab the driver and compile it for your own distribution: http://www.broadcom.com/support/802.11/linux_sta.php