Wi-Fi Direct vs. Bluetooth 4.0: A Battle for Supremacy

The fight is on for wireless device-to-device networking supremacy between a refreshed incumbent, Bluetooth 4.0, and a newcomer, Wi-Fi Direct. Both specifications are promising to make it easier for you to quickly transfer pictures, files and other data between two wireless devices such as your smartphone and laptop without the need for a Wi-Fi network or USB cable.

The Wi-Fi Alliance originally announced the Wi-Fi Direct specification in December, promising speedy data transfers over long distances between two devices. On Monday, the alliance said it has started certifying Wi-Fi Direct products that should hit store shelves before the end of the year.

Meanwhile, the Bluetooth Special Interest Group announced in July that it would soon start certifying Bluetooth 4.0 devices. Just like Wi-Fi Direct, Bluetooth 4.0 is promising speedy device-to-device transfers over long distances, and Bluetooth 4.0 devices should also hit the market in the coming months.

Can Wi-Fi Direct and Bluetooth 4.0 complement each other or will one crush the other in a wireless specification battle for the ages? Only time will tell. Until then, here's a quick look at the major highlights of Bluetooth 4.0 and Wi-Fi Direct.

Wi-Fi Direct? I thought Wi-Fi devices already had an ad hoc mode.

In Wi-Fi Alliance terms, ad hoc refers to an aging Wi-Fi device-to-device transfer method that was painful to set up and maxed out at data transfer speeds around 11 Mbps. Wi-Fi Direct, on the other hand, promises regular Wi-Fi speeds of up to 250 Mbps. Wi-Fi Direct also promises to be much easier to set up and use than ad hoc.

What's up with Bluetooth 4.0. Didn't we just get Bluetooth 3.0?

Bluetooth 4.0 is an upgrade from Bluetooth 3.0 that includes a power-saving feature called "low-energy technology." Basically, Bluetooth 4.0 is three Bluetooth specs in one. Bluetooth 4.0 not only uses the new low-energy technology, but also relies on high-speed data transfers introduced in Bluetooth 3.0 and so-called classic Bluetooth technology found in older Bluetooth specifications. The tricky thing is that Bluetooth 4.0's low-energy technology is not compatible with existing Bluetooth devices. However, that doesn't mean your new Bluetooth 4.0-equipped smartphone wouldn't be able to work with a Bluetooth 2.1 headset.

It means that a device that only uses Bluetooth's low-energy technology wouldn't be able to talk to an older Bluetooth device. Let's say you have a Bluetooth pedometer that only has Bluetooth 4.0's low-energy feature baked in (and not the other parts of the Bluetooth 4.0 spec). You wouldn't be able to transfer via Bluetooth the pedometer's data to an older laptop equipped with Bluetooth 2.1.

It should be pointed out, however, that manufacturers could incorporate low-energy technology into a newer device using Bluetooth 2.1 or Bluetooth 3.0. So the backward compatibility problem only affects older Bluetooth devices, and not the actual Bluetooth specifications.

Bluetooth 4.0 vs. Wi-Fi Direct: Speed

Wi-Fi Direct promises device-to-device transfer speeds of up to 250Mbps, while Bluetooth 4.0 promises speeds similar to Bluetooth 3.0 of up to 25Mbps. Both Bluetooth 4.0 and Wi-Fi Direct use the 802.11 networking standard to reach their maximum speeds. But whether Bluetooth or Wi-Fi Direct speeds will run as fast as promised in the real world remains to be seen. In other words, don't believe the hype and keep an eye on independent data speed tests to see how each specification performs.

How far can these specs travel?

The Wi-Fi Alliance is claiming that Wi-Fi Direct devices can reach each other at a maximum distance of 656 feet (more than two football fields) away. Why you would ever need that kind of distance between two devices is beyond me. Sufficed to say, it shouldn't be a problem for the laptop in your bedroom to communicate with the printer in your den via Wi-Fi Direct.

The Bluetooth SIG says that Bluetooth 4.0's maximum range is not dependent on the specification, but on the capabilities of the Bluetooth device. That said the Bluetooth SIG suggests a distance of at least 200 feet for a Bluetooth 4.0 device.

Security

Bluetooth 4.0 is using AES 128-bit encryption, while Wi-Fi Direct relies on WPA2 security, which uses AES 256-bit encryption. Both forms use key-based encryption and authentication methods, and both offer enough security for the average consumer.

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