NextNav, a provider of location services for indoor and urban environments, has raised $70 million in a Series D financing led by New Enterprise Associates and Oak Investment Partners. The funds will be used to commercialize its Metropolitan Beacon System positioning network. By using land-based sensors rather than satellites, MBS allows mobile phones and other devices to determine their location in places where GPS signals can't be received. According to SEC filings, NextNav also raised over $50 million in 2012, and over $19 million the year before. NEA and Oak Investment were joined in the Series D by Columbia Capital, Telcom Ventures and Goldman Sachs Investment Partners. NEA managing general partner Peter Barris will join the Board of Directors.