If you end up with no wlan after upgrading your Ideapad to Ubuntu to 12.04 Precise, then you are victim of a rare case: Ubuntu switched the wlan driver to an open source one for the b43 series of wireless card, like the Broadcom BMC4313 with PCI id 14e4:4727 that is used in the Ideapad U160.
But also, this firmware isn't free, so it isn't installed with the upgrade, leaving wlan in a non functional state.
To get wireless back, do this
sudo apt-get remove --purge bcmwl-kernel-source
sudo rm /etc/modprobe.d/blacklist-bcm43.conf
which deinstalls Broadcom STA related stuff that might have been installed before. Then make sure that the broadcom drivers aren't blacklisted in /etc/modprobe.d/blacklist.conf (look for things with "43" in the name, or "br cm")
and after that:
sudo apt-get install linux-firmware-nonfree
And your wireless should be up after the next reboot!
If this doesn't help, try your luck with the STA proprietary driver. (Which is the reverse of what we did above):
Select the STA driver