Ralink.For a list of all currently documented Ralink chipsets with specifications, see
Dual-Band Wireless-N USB Adapter with 3x3 Antenna
"Manufactured for CISCO", "48DNUR15.SGC", and "2011/12/20" is silkscreened on the board in the FCC photos.
rt2800usb chip info dump
ieee80211 phy3: rt2x00_set_rt: Info - RT chipset 3593, rev 0402 detected ieee80211 phy3: rt2x00_set_rf: Info - RF chipset 000d detected