Wi-Fi Direct (WFD): Wi-Fi without web
Midleware for IoT
Mesh, QoC, Security, Connectivity
The world of Wi-Fi has taken over to spread internet love without wires and is proving immensely popular - but that doesn't make it the best way to connect devices.
Wouldn't it be great if you could effortlessly connect your Wi-Fi-enabled devices without messing around with access points and lengthy passphrases? That's what Wi-Fi Direct promises.
Wi-Fi Direct doesn't need a wireless access point
Wi-Fi Direct devices can connect to each other without having to go through an access point, that is to say you don't need to use your router. This is because Wi-Fi Direct devices establish their own ad-hoc networks as and when required, letting you see which devices are available and choose which one you want to connect to.
Wi-Fi Direct is an official standard
It comes via the Wi-Fi Alliance, the global industry association in charge of certifying Wi-Fi kit. This means that you can be sure that any Wi-Fi Direct enabled technology has been set to work with all the others without the need for special hardware.
Wi-Fi Direct is Wi-Fi without the internet bit
The idea behind Wi-Fi Direct is that simple tasks need simple connections. Lets sat you want to print from your laptop or smartphone to a wireless printer, share images with someone sat across the room, or even send your holiday video from your phone to your TV. None of these things requires an active internet connection, or an internet connection at all, but they do need to connect - to the printer, or to the other person's hardware, or to the TV. With Wi-Fi Direct, that bit's easy.
Wi-Fi Direct uses Wi-Fi Protected Setup
Much like you have password protection on your home network, you don't want any Thomas, Richard or Henry to be able to connect to your stuff. You won't want to see what the neighbors are beaming to their TV on your TV nor do you want them being able to use your printer. In order to prevent this, Wi-Fi Direct uses Wi-Fi Protected Setup [PDF] and WPA2 to prevent unauthorized connections thus keeping your communications private. Pairing devices can be done in multiple ways; physical buttons - "press the button on gadget X and then the same one on gadget Y", with PIN codes, QR Codes or even NFC.
Wi-Fi Direct knows what's nearby
Wi-Fi Direct includes two potentially useful things: Wi-Fi Direct Device Discovery and Service Discovery. Devices won't just know there are devices available; if developers have enabled it, your device will know what kind of devices are nearby and what's on offer. This means that if you're trying to display an image, you'll only see devices that you can beam images to; if you want to print, you'll only see devices that are or that are connected to printers. Crucially this can happen before you connect, so you don't waste any time trying to connect so something that doesn't do what you want it to do.
Wi-Fi Direct uses the same silicon
Manufacturers don't need to add extra radios to their kit: the idea is to have Wi-Fi Direct as part of the standard Wi-Fi radio. It's backwards compatible too, so you don't need to throw out your old Wi-Fi-enabled kit. The Wi-Fi alliance currently claims that more than 1,100 devices have been certified since October 2010, including televisions, smartphones, printers, PCs and tablets.
Digital Living Network Alliance (DLNA) announced that it was including Wi-Fi Direct in its interoperability guidelines. Since then Google has added Wi-Fi Direct support to all versions of Android since Android 4.0 Ice Cream Sandwich.
Samsung has included Wi-Fi Direct since Android 2.3 on the Galaxy S2, although required to only connect to other Samsung devices. DLNA streaming is now common in every modern flagship including the HTC One, LG G2 and Sony Xperia Z1.
Wi-Fi Direct is even found inside the iPhone 5S having been baked into iOS7 in the form of Air Drop. Not keen on missing out, Miracast has Wi-Fi Direct running underneath. Even the new Xbox One comes equipped with the Wi-Fi Direct
Wi-Fi Direct (WFD) - FAQ
· How does service discovery work?= The Wi-Fi Peer-to-Peer Services Technical Specification defines a simplified standard for devices to advertise and discover services in nearby devices.
· What about power management protocols? Are devices implementing the technology behind Wi-Fi Direct a power hog?= Most WFD devices are power-sensitive, and in many cases, battery-powered. WFD-certified devices can support the Power Save feature certified under the WMM program, and the specification underlying the WFD program also defines new power saving mechanisms.
· Which WFD device will create and manage the connection? = Devices conduct a negotiation to determine which device is most appropriate. This may be determined by considering a number of factors including but not limited to power management, number of connections supported, richness of user interface and services being offered. The WFD-certified device that offers the connection manages the creation, admission to, presence and termination of that network implementing the specification underlying the WFD program.
· Can all devices start a network based on the specification underlying the WFD program?= All WFD devices can start a group, based on the specification underlying the WFD program, but it’s most likely that devices with more computing power (laptops, handsets, gaming devices) will more frequently manage the network than those with less power (digital cameras, printers, etc.).
· How does security work for WFD products?= Group networks based on the specification underlying the WFD program operate in a security domain that is independent from any infrastructure network. This means that they have protection of the security features certified under the WPA2 program, but are managed separately from the security system in the AP-based network (home, enterprise, hotspot). This means both the group networks based on the specification underlying the WFD program and the infrastructure networks can be protected, but users don’t need credentials for the infrastructure network to connect to the network based on the specification underlying the WFD program.
· How far does a WFD connection travel?= Wi-Fi Direct devices work just like any Wi-Fi device, with ranges up to 200 meters. They can connect from just a few feet away, but also across a home. This means that making a WFD group connection will be convenient, even when devices aren’t in immediate proximity to one another.
· How fast is WFD= Wi-Fi Direct supports typical Wi-Fi speeds, which can be as high as 250 Mbps. Even at lower speeds, Wi-Fi provides plenty of throughput for transferring multimedia content with ease. The performance of a particular group of WFD devices depends on whether the devices are 802.11a, g, or n, as well as the particular characteristics of the devices and the physical environment.
· How many devices can connect?= A WFD network can be one-to-one, or one-to-many. The number of devices in a WFD group network is expected to be smaller than the number supported by traditional standalone access points intended for consumer use. Connection to multiple other devices is an optional feature that will not be supported in all WFD devices.
· Can a device simultaneously connect to a regular Wi-Fi network and a group of WFD devices at the same time?=
All devices certified under the WFD program allow the user to connect to an infrastructure or a WFD network. Some devices certified under the WFD program support connections to both an infrastructure network and WFD group at the same time (e.g. a laptop may support an infrastructure connection while also belonging to a WFD group).
Example 3: AUTOMOTIVE
General Motors leverages Wi-Fi Direct to give pedestrians a better chance of jumping out of the way of cars.
GM & Honda uses WFD as intelligent cheap radar - part of autonomous driving toolbox
Mr. Thilo Koslowski, (VP at Gartner Inc.) “Not only can Wi-Fi Direct help vehicles seamlessly communicate with other consumer devices, it can also augment vehicle-to-infrastructure communications as well, which could lead to better traffic management and fewer accidents”