802.11


Also found in: Dictionary, Thesaurus, Medical, Acronyms.

802.11

The Wi-Fi standards. IEEE 802.11 standards cover every version of Wi-Fi, and the Wi-Fi Alliance, certifies products. Wi-Fi is the wireless counterpart to "wired" Ethernet, and Wi-Fi and Ethernet co-exist in every home and business.

All versions of 802.11 use OFDM encoding except for 802.11b, which uses DSSS (see OFDM and spread spectrum). For details about each standard, see below and 802.11 versions.

Infrastructure and Ad Hoc Modes
In "infrastructure" mode, Wi-Fi devices transmit to an "access point" (base station), which may be a stand-alone unit or built into a wireless router. In "ad hoc" mode, two devices communicate peer-to-peer without an access point in between (see Wi-Fi Direct).

Throughput Varies
Speed is distance dependent. The farther away the device from the base station, the lower the speed. Also, the actual throughput is generally half of the rated speed because 802.11 uses collision "avoidance" (see CSMA/CA) rather than Ethernet's collision "detection" method (see CSMA/CD). For example, a rated 54 Mbps may yield 27 Mbps in real data throughput. For more about Wi-Fi networks, see wireless LAN and Wi-Fi. See Wi-Fi hotspot, 802.11 timeline, wireless router, ISM band, 802.16 and 802.15.

    802.11 SPECIFICATIONS                Max    Indoor  ChannelWi-Fi   Bands Speed   Range*   Width No.    (GHz) (Mbps)  (ft)     (MHz)1 11b  2.4      11    150  20
 2 11a       5   54     95  20
 3 11g  2.4      54    170  20
 4 11n  2.4, 5  150**  230  20/40
 5 11ac      5  433*** 230  20/40/80/160
 6 11ax 2.4, 5  600*** 230  20/40/80/160

  ** = Per antenna at 40 MHz channels.
 *** = Per antenna at 80 MHz channels.


Stand-Alone Access Points
Wi-Fi access points (APs) are central base stations with antennas. These examples are stand-alone APs (ceiling mounted and desktop). They are generally not found in homes because an AP is already built into the wireless router.


Stand-Alone Access Points
Wi-Fi access points (APs) are central base stations with antennas. These examples are stand-alone APs (ceiling mounted and desktop). They are generally not found in homes because an AP is already built into the wireless router.







Wi-Fi Adapters
The adapter (top) adds Wi-Fi to any computer via USB, while the card on the bottom plugs into a PCI slot inside a desktop computer. (Images courtesy of D-Link Corporation and TP-LINK Technologies Co., Ltd.)
References in periodicals archive ?
The lawsuit in Seattle involves two standards-- Institute of Electrical and Electronics Engineers' 802.11 wireless local area network standard and the International Telecommunication Union's H.264 advanced video coding technology standard.
Because both false alarm and missed-detection will affect the performance of IEEE 802.11 DCF, their impact on throughput of IEEE 802.11 needs to investigate.
The MAC sublayer [1] of the IEEE 802.11, defines the distributed coordination function (DCF), the point coordination function (PCF), the hybrid coordination function (HCF).
Many 802.11 DoS vulnerabilities were experimentally demonstrated in recent years.
"The new Bluetooth specification gets its performance from the 802.11 MAC/PHY with built in enhanced power control.
WIRELESS STANDARDS Data Throughput Data Throughput Standard (Theoretical Speed) (Practical Speed) 802.11 Up to 2 Mbps 1 Mbps 802.11b 11 Mbps 6 Mbps 802.11g** 54 Mbps 27 Mbps (g-only networks) 9-13 (b/g combination networks) 802.11a 54 Mbps 27 Mbps 802.11 super a + g 108 Mbps 54 Mbps 802.11h 54 Mbps 27 Mbps Standard Frequency Band High Interference 802.11 2.4-2.4835 Ghz Yes* 802.11b 2.4-2.4835 Ghz Yes 802.11g** 2.4-2.4835 Ghz Yes 802.11a 5.12-5.25 Ghz No 5.47-5.725 Ghz 5.725-5.825 Ghz 802.11 super a + g 2.4 GHz 802.11 b/g No or dual band 2.4/ 5 GHz 802.11 a/b/g 802.11h Same as 802.11a No *Since 2.4 GHz has only three non-overlapping channels, users may share this frequency with their neighbors' wireless networks or other wireless devices, such as cordless phones and microwave ovens.
Info-Cop's cross-platform functionality is highly adaptable, providing the ability to make a seamless connection to any potential partner department using any IP-based network including conventional radio frequencies and advanced 1XRTT, EVDO, GPRS, EDGE 802.11 and CDPD networks.
Bruce Alexander's 802.11 Wireless Network Site Surveying And Installation (1587051648, $55.00) is a recommended pick for wireless LAN installers who want a technical key to site surveying methods.
Available this fall, the SoftIPT SoftPhone allows users to access their telephone features from virtually any location by connecting to the enterprise's Toshiba Strata CIX native IP business communications system or Strata CTX digital business communications system, through 802.11 wireless networks.
Wi-Fi theoretical data rates are up to 11Mbps for 802.11 b and 56Mbps for 802.11 g and 802.11 a.
Arbaugh] take this information and focus on assessing inherent wireless network security deficiencies and seeking solutions for 802.11 based networks....
Kawasaki Microelectronics (K-micro), a provider of advanced ASICs, has joined the Wi-Fi Alliance, a non-profit organization formed to certify interoperability of IEEE 802.11 products and to promote them as the global, wireless LAN standard across all market segments.