People love talking about how everything will be delivered by drones in the future, which will be better for some reasons. So far drone delivery has all been focused on dropping stuff outside your house, much like delivery people do already. Cambridge Consultants, on the other hand, is thinking beyond that.
Since drones aren't limited by terrain the same way delivery drivers are, they wondered why they should be limited to delivering items to a pre-set address or post code. So they developed DelivAir, a delivery drone concept that delivered stuff to the person that ordered it, rather than dropping it outside of their house. It doesn't matter where they are, provided they have a smartphone on their person.
The delivery is a two stage process. It starts with the drone using GPS to track your smartphone location, periodically requesting secure updates to make sure it's on the right path. Once the drone is in visual range it starts using optical tracking, 3D imagery, and a ranging system to locate you.
Naturally it'll make sure you are you, asking you to point your phone's flash at the sky so it can blink a coded pattern at the drone. After confirmation you are you (or that it's your phone, at least) the package will be lowered into your hand using a stabilised winch. The drone itself will hover above the ground so the rotors don't slice anybody open.
It's a great idea, since you don't have to hover around your house because you're expecting a delivery. It also means you can get something delivered regardless of where you are. Cambridge Consultants uses the example of getting emergency supplies, or a hiker needing a first aid kit, though we all know this sort of tech will be used to sneak booze into festivals and other similar events.