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IEEE 802.11

IEEE 802.11 or WiFi denotes a set of Wireless LAN standards developed by working group 11 of IEEE 802.

The current IEEE standard is 802.11b. Network cards for this standard are becoming a commodity (as of Sept, 2001), thus for the first time wireless computer networks, previously only a niche market, are becoming practical. Now with the proliferation of cable modems and DSL, there is an ever-increasing market of people who wish to establish small networks in their homes to share their high speed Internet connection. Wireless office networks are often not protected and let "people on the street" connect to the internet. There are also efforts by volunteer groups to establish wireless community networks to provide free wireless connectivity to the public.

802.11b has a range of about 150 feet (50 meters) and a theoretical maximum throughput of 11 Megabits per second (Mbps); in practice the maximum throughput is about 5,5 Mbps. Particularly thick walls, and large amounts of concrete can decrease the range drastically. 802.11 runs in the 2.4 GHz spectrum and uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) as its media access method.

With high-gain external antennas, the protocol can also be used in fixed point-to-point scenarios (5 miles (8 kilometres), reports of up to 50-75 miles (80-120 kilometres) line of sight[?]) to replace costly leased lines, or in place of very cumbersome microwave communications gear. Current cards can operate at 11 Mbps, but will scale back to 5.5, then 2, then 1, if signal strength is an issue.

The next 802.11 protocol, 802.11a, is now complete. It offers raw throughput of up to 54Mbps and operates in 5GHz frequency bands. 802.11a may be less useful than 802.11b for home users, as internal walls absorb the higher frequency 11a signals more than the 2.4GHz signals of 11b.

As of July 2002, work on 802.11g, which offers 54MBit/s connections in the 2.4 GHz band, continues.

The following standards and task groups exist with the working group:

  • IEEE 802.11 - The original 2 Mbit/s, 2.4 GHz standard
  • IEEE 802.11a - 54 Mbit/s, 5 GHz standard (2002)
  • IEEE 802.11b - Enhancements to 802.11 to support 11 Mbit/s (1999)
  • IEEE 802.11d - new countries
  • IEEE 802.11e - enhancements: QoS
  • IEEE 802.11f - Inter-Access Point Protocol (IAPP)
  • IEEE 802.11g - 20 Mbit/s, 2.4 GHz standard (forthcoming)
  • IEEE 802.11h - 5 GHz spectrum and transmit power management
  • IEEE 802.11i - Enhanced security

Many of the supplementary (lettered) standards will probably be incorporated into a future edition of the base 802.11 standard.

The Wi-Fi Alliance (formerly known as the Wireless Ethernet Compatibility Alliance) is a trade organization[?], with the aim of promoting interoperability between Wireless Ethernet networks from different vendors. The "Wi-Fi" logo is a registered trademark of Wi-Fi Alliance.

In 2001, a group from the University of California at Berkley[?] presented an paper describing a weakness in 802.11b[?] described by Fluhrer, Mantin, and Shamir entitled "Weaknesses in the Key Scheduling Algorithm of RC4". This presentation was soon followed by Adam Stubblefield and AT&T publicly announcing the first verification of the attack. In the attack they were able to intercept transmissions and gain unauthorized access to wireless networks.

The IEEE set up a dedicated task group to create a replacement security solution, 802.11i (previously this work was handled as part of a broader 802.11e effort to enhance the MAC layer). Whilst 802.11i is still a work in progress, and is not expected to be completed until late 2003, the Wi-Fi Alliance has announced an interim specification called Wireless Protected Access (WPA) based on a subset of the current IEEE draft. This is expected to appear in products early in 2003, and implementation will be mandatory in order to display the Wi-Fi logo.

See also:

  • Bluetooth, another wireless protocol primarily designed for shorter range applications.
  • Apple Airport, with implementations of 802.11b and 802.11g .

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