I was under the impression AirDrop used bluetooth and ADhoc?
When AirDrop is activated, it uses Bluetooth to scan for nearby devices that are advertising discoverability. User can elect to be seen by everyone, only by contact, or not at all if the feature is turned off
Once a connection is established via Bluetooth, an ad-hoc Wi-Fi network is created to link the two devices together, allowing for faster transfer speeds. Basically, Bluetooth is used for discovery and token setup, while the more robust Wi-Fi protocol is leveraged for transfers.
from: http://appleinsider.com/articles/13/09/18/ios-7-feature-focus-airdrop-simplifies-speedy-local-file-transfer