Go to software & Updates, enable"Proprietary drivers for devices"
Reload sources, and apt-get upgrade
It'll grab the latest broadcom drivers and intel microcode, you'll need to disable secure boot if its enabled, reboot, and it should work.
Did it on my 9343 to 16.04 with kernel 4.4.0-21-generic
disabling Secure Boot Mode required
this case i set to :UEIF+NoSecureBoot