Wi-Fi Direct

Wi-Fi Direct is a standard for transmitting data between two wireless devices without a central access point. Wi-Fi Direct is based on the international standard IEEE 802.11 ( ISO / IEC 8802-11 ), which describes the properties of a wireless network. "Wi- Fi Direct " - enabled devices certified by the Wi- Fi Alliance; this ensures that interoperability is at least guaranteed certified devices between Wi -Fi.

Background

Products they want to come as "Wi- Fi Direct " capable in trade must be certified by the Wi- Fi Alliance. The consortium was founded in 1999 and aims to ensure the interoperability of devices that are authorized under the IEEE 802.11 standard. The tests are based on its own guidelines. Devices that pass the test are awarded the "Wi- Fi Certified " logo.

Technical operation

The special feature of "Wi- Fi Direct " enabled devices is that they can communicate directly with each other. Instead of using the data cable, for example, from a computer are transmitted to a mobile phone or a digital camera to a printer via radio waves at the frequencies of 2.4 GHz or 5 GHz. In contrast to a conventional WLAN access point and no more no hot spot is for data transfer is necessary - a Wi -Fi enabled devices can itself act as a base station.

For "Wi- Fi Direct " enabled devices are equipped with a software access point. About this they are able to recognize other wireless or Wi -Fi -enabled devices in the vicinity. Using different protocols - Universal Plug and Play ( UPnP ) Device Profile for Web Services ( DPWS ) and Apple's Bonjour software - identify "Wi- Fi Direct " - capable devices other ad hoc devices that can communicate with them. This must have the "Wi- Fi Direct " standard does not necessarily also; it is sufficient if they are compatible wireless capability and with the 802.11 standard.

Two devices can join over Wi-Fi Direct, as well as groups of devices. The installation of a Wi -Fi network should be kept as simple as possible for the user and, therefore, via the Wi -Fi Protected Setup, introduced in 2007 means entering a PIN at the access point or by pressing a -. Real or virtual - buttons will set up your network. The Wi -Fi Protected Setup can be done in different ways:

  • The entry of a personal identification number ( PIN) at the access point;
  • Push- button method: The user must press a button on both the access point and on the Wi -Fi - enabled device;
  • Near Field Communication: In this method, it is sufficient to bring the new Wi -Fi enabled device in the vicinity of the access point;
  • Data for the network setup between the new terminal and the access point are transferred via USB.

Areas of application

Virtually every digital device can act as a "Wi- Fi Direct " -enabled access point. Has increased the importance of the 802.11 standard with the proliferation of smartphones. The data transfer from the smartphone to the computer and vice versa via Wi-Fi Direct uncomplicated and wirelessly. It is also possible to send data from your computer via Wi -Fi Direct to a printer on the network or from a digital camera to a printer or a digital picture frame.

Frequencies

Be used license-free frequency ranges around 2.4 and 5 GHz. These frequencies are not occupied by radio, telephone or television signals.

"Wi- Fi Direct " generations

There are now different "Wi- Fi Direct " generations. All are approved according to the 802.11 standard and are identified with a letter on. The since September 2010 current Wi-Fi Direct generation bears the name of 802.11g. It is backward compatible with the older generations, provided that spark on the same frequency. A device that is approved in accordance with the 802.11g standard, therefore, can also be a device of the generation 802.11b communicate. The extended standards are characterized either improved transfer rates, or they define security and interoperability standards again. The standard most commonly used today is 802.11b, which transmits at a frequency of 2.4 GHz on three radio channels. For meaning for the end user are the standards 802.11a, 802.11b, 802.11g and 802.11n. The other standards do not bring relevant improvements for end users, define the Wi -Fi standard, however accurately.

Bandwidth and range

The Advantages of Wi-Fi Direct over Bluetooth to lie primarily in the greater range. Outdoors so be it possible to bridge up to 500 meters without any antenna without amplifier, indoors after all, up to 90 meters - walls and ceilings but also weaken the Wi -Fi signal.

Wi-Fi Direct guarantees not only a long range and a high data transfer rate. However, this depends on the spatial distance of the respective devices: The greater the distance between the "Wi- Fi Direct " - enabled devices, the lower the bandwidth, the data transfer is possible. However, the range of devices with Wi -Fi 802.11b is at a bandwidth of 54 Mbps ( megabits per second max. Gross data rate ) about 10 meters indoors, at a bandwidth of 6 Mbps as 70 meters.

Security

Data security is a sensitive topic in radio transmission. As of 2003, the Wi-Fi Alliance certified encryption method Wi- Fi Protected Access, or WPA, to increase the security of your Wi -Fi network. This standard replaced the hitherto common but regarded as insecure WEP from, but is now classified as unsafe and should be replaced where possible by WPA2. On most devices, the time of delivery are only the factory security measures active. When operating the unit, at the latest when configuring a Wi -Fi network, the device should be possible to get a new username, but in any case a new password.

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