Strong peer-to-peer mode added to Wi-Fi portfolio: The Wi-Fi Alliance has announced Wi-Fi Direct, a peer-to-peer wireless networking method that takes the group into a new realm of creating specifications de novo, instead of following IEEE groups. The spec will appear in hardware by mid-2010.
Wi-Fi Direct will allow any device to advertise itself as a combination of software access point and peer. Newer hardware--which will include some existing equipment with firmware upgrades--will be able to maintain a wireless LAN connection to a so-called infrastructure network (via an access point), while also creating a peer-to-peer link to a device like a printer, mouse or keyboard, computer, or handheld. This could be used for file transfers, printing, input, and synchronization, among other purposes.
The spec is backwards compatible with 802.11a and 802.11g, which will see the peering device as a software access point, if I understand that detail correctly.
Wi-Fi Direct will include mechanisms for advertising service availability without connecting, something like the Apple Bonjour method known generically as Zeroconf that uses DNS records to broadcast specific services over a LAN.
The new method is a wholesale replacement of the weak ad hoc networking mode that's part of 802.11, but never built out into a standardized, certified part of Wi-Fi. Ad hoc networks allow devices to exchange data with each other without an access point, but implementations almost universally offer poor security and degraded throughput.
Distinct from ad hoc networks are software access points, which mimic all the functionality of an infrastructure network, and must be operated in a continuous fashion on a computer.
The Wi-Fi Direct mode will not suffer from weaknesses of either type of quasi peer-to-peer methods, and will be rigidly tested for interoperability among devices. Kelly Davis-Felner, the alliance's marketing director, said in an interview that Wi-Fi Direct can preserve the full bandwidth of 802.11n, as well as use WPA2 encryption and WPS (Wi-Fi Protection Setup) secure key handling.
Davis-Felner also said that while the spec has a lot of consumer electronics and home user advantages, enterprise management was baked in as well. The spec requires "Wi-Fi Direct networks to be seen by enterprise APs, and, potentially to be shut down by them" to prevent rogue networks that violate policy, she said. The spec also includes optional mechanisms that allow enterprise access points to suggest channel assignments and power management choices. The spec was designed to be an "enterprise-acceptable solution," Davis-Felner said.
The alliance has pulled together support from many non-standardized PAN/WLAN hybrid modes that have been under development, most notably the Intel My WiFi personal area networking (PAN) extension of 802.11. Intel said via email that Wi-Fi Direct would be incorporated into Intel My WiFi, which has additional capabilities. (My WiFi supports up to eight devices in a PAN configuration, much like Bluetooth.)
Chipmaker Atheros also offers its Direct Connect mode (in addition to a soft access point feature), which it said via email can converge into Wi-Fi Direct. (Oddly, Atheros has no plain product briefing page on this mode.) Marvell has a similar hotspot-on-a-chip offering, and plans Wi-Fi Direct support.
"This has been by far one of the most dynamic and heavily participated in groups that we've had in the Alliance," Davis-Felner said.
Wi-Fi Direct is a bit of a departure for the Wi-Fi Alliance, which typically develops a set of parameters from IEEE standards that a Wi-Fi-compliant device should support, and then builds interoperability testing and certification around those parameters.
With the initial release of Wi-Fi Protected Access (WPA), the Wi-Fi Alliance reacted to the interminable delays at the 802.11i security task group by splitting the backwards-compatible components from all the future-looking elements. WPA was based on an interim 802.11i draft, but ultimately was updated to WPA2 to incorporate the final work of the group.
Here, the alliance isn't following the IEEE, which has no PAN/WLAN convergence group, but maintains separate WLAN (802.11) and PAN (802.15) efforts. The 802.15 group has famously suffered from mid-stream shifts in technology approaches and the disbanding of 802.15.3b (high-speed PAN using UWB).
Wi-Fi Direct could be seen as a challenge to Bluetooth, given that Bluetooth is designed entirely as a PAN, and has a specification that will soon see light that allows Bluetooth to trigger an 802.11-compatible bulk-transfer mode for large files at faster rates. Bluetooth had paired itself with UWB as its next-generation wireless medium, but generic UWB radios never reached market, although there's still some potential.