Source: http://gizmodo.com/lte-direct-will-let-your-phone-get-alerts-with-no-tower-1640722664
Picture this. You walk into the subway but you don't lose service. Instead, your phone lights up with useful alerts—the train is delayed, a nearby kiosk is running a sale, your friend is standing on the other end of the platform. Meanwhile, there's not a cell tower within 500 yards. This is the world powered by the future of smartphones: LTE Direct.