it's not going to happen. not at ULTRA settings anyway.
you either have to lower the settings or raise the budget.
Remember that a Mobile graphics card performance is alot lower that its desktop version.
a 7970m =/= 7970
its roughly 1/2 the performance of the desktop card.
a 7970m will only get around 40fps on ULTRA @1080
I would say something at about the $2000 mark will run High i think ultra @1080p will be very hard even in a top of the range laptop ($3000+) http://www.tomshardware.com/reviews/battlefield-3-graphics-performance,3063.html