Understanding Wi-Fi Direct

Paul Mah

The Wi-Fi Alliance this week announced that it has started certifying Wi-Fi Direct-capable products. Designed to give Bluetooth a run for its money, Wi-Fi Direct is touted as offering the option for device-to-device connectivity with the distance and performance inherent to infrastructure mode. In fact, fellow blogger Carl Weinschenk wrote a superb comparison between Wi-Fi Direct and Bluetooth 4.0 here.


I realized from reading various news reports, however, that they don't cover enough depth for me to understand how Wi-Fi Direct actually works. Rather than take the various marketing claims and figures at face value, I decided to dig a little deeper to better identify the business implications that might be at stake. Not surprisingly, it took some digging to figure out how Wi-Fi Direct actually functions behind the scenes.


Here's a short summary of what I found:

  • Wi-Fi Direct works by embedding a "software" access point (AP) in devices that support Wi-Fi Direct. Wi-Fi Protected Setup is supported by this soft AP for ease of setup.
  • Legacy (non Wi-Fi Direct) devices can join a Wi-Fi Direct network, since the Wi-Fi Direct device will have the requisite soft AP.
  • Upgradability of legacy devices will vary, and depends on vendors offering software upgrades.
  • A Wi-Fi Direct certified network can be one-to-one or one-to-many. Not all devices will support connection to multiple other devices, however, as this is listed as an optional feature under the specification.
  • Wi-Fi Direct works across 802.11 a, g and n standards. All Wi-Fi Direct devices will work in the 2.4GHz frequency band, and "some" of them will work in the 5GHz to enable connecting to 802.11a networks. The Wi-Fi Alliance does say that many devices will operate in both frequency bands.
  • Wi-Fi Direct supposedly supports up to 200 meters range and 250Mbps transfer speeds. Taking normal, infrastructure-mode Wi-Fi setup as a guide though, I think it is safe to say that the real-world range and speed will be significantly lower and highly dependent on actual environments.
  • Simultaneous connection to a Wi-Fi Direct and a normal infrastructural AP is possible, but dependent on support from individual devices. A laptop operating in Wi-Fi Direct and AP mode simultaneously was used as an example though, so it is probably safe to say that the Wi-Fi Alliance will be pushing for simultaneous modes to be supported in desktop operating systems.
  • On the security front, devices connected via Wi-Fi Direct "operates in a security domain separate from the infrastructure network"-even when devices are simultaneously connected to both.
  • As additional security, APs can opt to prevent Wi-Fi Direct devices from connecting.

The above information was obtained from the official Wi-Fi Alliance website, and the Frequently Asked Questions here (pdf). While the verdict is still out as to how helpful Wi-Fi Direct will prove to be in business, I do have some thoughts on the business implications of Wi-Fi Direct, which I shall share in a later blog.

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