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Wireless standards

·802.11 — This early wireless standard provides speeds of up to 2 Mbps. Because 802.11 supports two entirely different methods of encoding—Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS)—there is often incompatibility between equipment. 802.11 has also had problems dealing with collisions and with signals reflected back from surfaces such as walls.

·802.11a — This is an extension of the 802.11 standard and uses a different band than 802.11b and 802.11g—the 5.8-GHz band called Unlicensed National Information Infrastructure (U-NII) in the United States. Because the U-NII band has a higher frequency and a larger bandwidth allotment than the 2.4-GHz band, the 802.11a standard achieves speeds of up to 54 Mbps.

·802.11b — This extension of the original 802.11 standard boosts wireless throughput from 2 Mbps to 11 Mbps. It can transmit up to 328 feet (100 m) under good conditions, although this distance may be reduced considerably by obstacles such as walls. This upgrade has dropped FHSS in favor of the more reliable DSSS. Settling on one method of encoding eliminates the problem of having a single standard that includes two kinds of equipment that aren?t compatible with each other. 802.11b devices are compatible with older 802.11 DSSS devices but are not compatible with 802.11 FHSS devices. 802.11b is currently the most widely used wireless standard.

·802.11g — 802.11g is an extension to 802.11b and operates in the same 2.4-GHz band. It brings data rates up to 54 Mbps using Orthogonal Frequency-Division Multiplexing (OFDM) technology. Because 802.11g is backward compatible with 802.11b, an 802.11b device can interface directly with an 802.11g access point. You may even be able to upgrade some newer 802.11b access points to be 802.11g compliant via relatively easy firmware upgrades.

·802.11i — 802.11i addresses many of the security concerns that come with a wireless network by adding Wi-Fi Protected Access (WPA) and Robust Security Network (RSN) to 802.11a and 802.11b standards. WPA uses Temporal Key Integrity Protocol (TKIP) to improve the security of keys used with WEP, changing the way keys are derived and adding a message-integrity check function to prevent packet forgeries. RSN adds a layer of dynamic negotiation of authentication and encryption algorithms between access points and mobile devices. 802.11i is backwards compatible with most 802.11a and 802.11b devices, but loses security if used with non-802.11i devices.

·802.11n — The next standard in development is IEEE 802.11n. This new standard offers far higher speeds than current standards. Speed projections are at least 100 Mbps, but they could go up to 320 Mbps. The standard isn?t expected to be ratified until November 2006.

·802.11X — This refers to the general 802.11 wireless standard—b, g, or i. It is not to be confused with 802.1X, a security standard.

·802.15 — This specification covers how information is conveyed over short distances among a Wireless Personal Area Network (WPAN). This type of network usually consists of a small networked group with little direct connectivity to the outside world. It is compatible with Bluetooth 1.1.

·802.16 — IEEE 802.16, was ratified in January 2001. It enables a single base station to support many fixed and mobile wireless users. It is also called the Metropolitan Area Network (MAN) standard. 802.16 aims to combine the long ranges of the cellular standards with the high speeds of local wireless networks. Intended as a ?last-mile? solution, this standard could someday provide competition for hard-wired broadband services such as DSL and cable modem. 802.16 operates in the 10- to 66-GHz range and has many descendants.

·802.16d — This recent standard—also called the IEEE 802.16-2004 standard or WiMax—can cover distances of up to 30 miles. Theoretically, a single base station can transmit hundreds of Mbps with each customer being allotted a portion of the bandwidth. 802.16d may use either the licensed 2.6- and 3.5-GHz bands or the unlicensed 2.4- and 5-GHz bands.

·802.16e — This is based on the 802.16a standard and specifies mobile air interfaces for wireless broadband in the licensed bands ranging from 2 to 6 GHz.

·802.20 — Specifies mobile air interfaces for wireless broadband in licensed bands below 3.5 GHz.

·802.1X — 802.1X is not part of the 802.11 standard. It is a sub-standard designed to enhance the security of an 802.11 network. It provides an authentication framework that uses a challenge/response method to determine if a user is authorized. See EAP.