i make lot of search and drivers download and finally i found the answer myself..
1.u need to buy WWAN Card like the 1st image..
2.and connect the card to u'r laptop WWAN slot like 2nd image
3.and remove u'r battery. connect u'r sim card in the sim card slot..
4.install the 5540 hspa mini card driver http://www.dell.com/support/drivers/us/en/19/DriverDetails/Product/xps-l502x?driverId=WGVYG&osCode=w...