The Institute of Electrical and Electronics Engineers (IEEE) is perhaps the most important IT-related standards body, and 802.11 is arguably the most successful IEEE standard after 802.3, which is usually referred to as Ethernet. And, like 802.3, 802.11 is in fact a family of standards. We need to begin with this point because it's a source of significant confusion.

802.11 uses suffix letters to name each working group (WG), the subcommittees that develop specific extensions to the standard. These letters are assigned sequentially over time and no ranking or hierarchy is implied - an important point to remember as we look at each WG below. Also, some WGs are developing extensions to the physical (PHY) layer of the standard, and some are enhancing the medium-access control (MAC) layer.

PHYs are specific definitions of radios (the vehicles that put information on and take it off the air); the MAC is common to all PHYs and contains such functionality as the definition of how individual stations access the airwaves in an orderly fashion, power management, security, and many other functions. Some additional functionality, common to all IEEE 802 networking standards, is defined in IEEE 802.1. This "above the MAC" repository defines such capabilities as the highly-visible 802.1x authentication standard. But the choice of whether to use 802.1 or any other networking strategy or features is usually up to the enterprise or the specific user - it's not part of 802.11.

The original 802.11 standard was approved in June of 1997, after more than seven years of work - a long time by IEEE standards (so to speak). This first standard specified several (incompatible) flavors of one- and two-Mbps PHYs, and a broad range of MAC features - many of which, as it turned out, needed significant additional work. Couple this with the fact that 1 and 2 Mbps just weren't fast enough, and the suffixes began to appear.

The most important of these were 802.11a and 802.11b, both completed in September of 1999. 802.11b defines up to 11 Mbps in the 2.4 GHz. unlicensed band, and 802.11a specifies up to 55 Mbps in the 5+ GHz. bands. Both of these chunks of spectrum are available in various parts of the world, subject, of course, to local regulations. .11b was first to market since it was easier to engineer products based on it. But .11a products are today plentiful and much less expensive than they used to be, and .11a's higher throughput and more available radio channels (12 vs. the three non-overlapping channels in .11b and g) make it attractive in enterprise and consumer-electronics applications. .11b was recently augmented by 802.11g, which essentially takes the higher-performance technology of .11a and applies it to the 2.4 GHz. band, while maintaining backwards compatibility with 802.11b - well, sort of. One can't operate 802.11b and 802.11g simultaneously in a single channel because they're incompatible. A "protection" mechanism makes its possible, however, for the two to coexist in an orderly manner. Regardless, the future belongs to multi-mode client

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