As computers get easier to use, once-“magical” features like Wi-Fi and Bluetooth begin showing usability issues. Although every modern computer operating system includes the ability to share files locally, it is usually a major hassle setting things up. Apple intends to remedy this situation with AirDrop, a Wi-Fi-based local filesharing protocol built into Mac OS X “Lion”. How exactly does AirDrop work? Let’s take a look.
Wi-Fi is no simple technology. Modern Wi-Fi radio chipsets include multiple transmitters, receivers, and antennas. These are normally used to boost throughput for a single link, but it’s possible to do much more with these radios.
A little-known feature in Microsoft Windows is Wi-Fi virtualization, allowing certain Wi-Fi chips to act as both a client and a base station at the same time. In this way, a Windows 7 machine can simultaneously access a Wi-Fi network and share that network with multiple clients.
Another new trick for Wi-Fi is “Wi-Fi Direct”, a short range communication protocol that functions similarly to Bluetooth but uses Wi-Fi hardware instead. The first Wi-Fi Direct hardware is just beginning to appear in early 2011, in the form of chipsets from the major vendors as well as a mouse from HP and a card from Eye-Fi.
Apple’s AirDrop is functionally similar to a hybrid between Wi-Fi direct and Wi-Fi virtualization, but it is a proprietary Apple protocol. AirDrop allows two computers (running Mac OS X “Lion” on compatible hardware) to transfer files in a friendly, no-configuration-required mechanism direct from Finder.
AirDrop will prove useful in business and classroom settings where one must quickly and easily move files between computers. A teacher could open AirDrop and collect assignments from students or pass out new materials, and collaborators in a conference room or airport could quickly exchange information.
The AirDrop interface itself seems fairly robust and secure, with no permanent connections or authentication. AirDrop is only active when one clicks on the icon in Finder, and every file transfer requires permission on both the sending and receiving systems. AirDrop connections are firewalled, and it automatically encrypts all transactions using TLS, so snooping is not much of a concern either.
AirDrop support is limited to Mac OS X “Lion”, and requires modern Wi-Fi hardware from Atheros or Broadcomm. Most recent machines include capable hardware, but the early Broadcomm BCM4321 found in the early 2009 Mac Mini is not supported. And AirDrop does not use Wi-Fi Direct, being a proprietary protocol developed by Apple. This makes it unlikely that it will spread beyond the Macintosh computer range.
Apple has not indicated that AirDrop will spread to iOS devices like the iPhone and iPad, but it seems a logical and useful addition. But these devices have a very basic Wi-Fi implementation, lacking multiple spatial streams. If they do not support AirDrop and Wi-Fi simultaneously, Apple may still enable it as an either/or option.
Apple has aggressively moved to eliminate “superfluous” peripherals and connections, wiping out the floppy and now selling a number of machines without optical drives. AirDrop continues this progression, attacking the prime use case for USB flash drives.
One can imagine an exciting use case for this technology, but it is disappointingly limited to recent Macs running the latest operating system. It would certainly be more consumer friendly if Apple had decided to leverage Wi-Fi Direct and expanded support to PCs and iOS devices. Sadly, the only likely expansion of AirDrop is to the iPad and iPhone.