After try at least 6 different drivers options, only rolling back to 15.3.1.2 (extracted to Dell set cited above) improved consistently performance on Samsung series 5 NP530U3C. I uninstalled temporally Intel WiFi Proset, BT and Widi, but at least the ultrabook maintain a stable connection from 133 to 144 mbps (connected with a TPLink modem-router W8960 at 2.4 Ghz, fixed at channel 1, at 5 o 6 meters distance without obstacles). Previous options (Samsung wifi set 15.0.0.75 OEM or other Intel software and drivers from delivered april to date) were highly unstables. I never can roll back to the old Windows drivers.
This is the only option as good as my other 2 old laptops equiped w/Atheros and Broadcomm, performing without flaws at 150 mpbs in same conditions. I need to check now the performance in transit from one router to other, annoyingly erratic with previous choices.