Apple has acquired WifiSLAM, a Silicon Valley-based startup that specializes in indoor GPS technology, according to The Wall Street Journal. Apple has confirmed the acquisition but refused to elaborate on details, although The Wall Street Journal reports that WifiSLAM was acquired for approximately $20 million. WifiSLAM develops technology that enables mobile apps to detect the location of a user within a building. The technology is expected to be used for retail, event and social networking applications that help companies understand indoor traffic patterns within locations such as shopping malls, stores and sporting arenas. WifiSLAM reportedly has technology that can locate users to within a 2.5 meter radius of accuracy as reported in GigaOM. The acquisition is seen as a move to bolster Apple’s technology in the mapping and GPS space in order to position itself more strongly against Google, whose Google Maps technology runs on both Android and Apple devices. Google, meanwhile, is no stranger to the indoor maps space and claims more than 10,000 indoor floor plans hailing from 13 countries. Apple’s acquisition of WifiSLAM is set to complement its acquisitions of mapping technology companies such as Poly9 and C3 Technologies. Apple’s September 2012 debacle debut of its proprietary mapping technology may have driven the acquisition but the question remains as to whether the Cupertino tech giant is late to the indoor-GPS party. Meanwhile, Gartner reports that revenue from location based services such as indoor-GPS technology will reach $13.5 billion in 2015, up from approximately $2.2 billion in 2009, with most of the revenue derived from smartphone-driven advertising.