Cheat Sheet: The A-Z of 802.11

The wireless LAN standard that's on everyone's lips, in all its tasty flavours...

Wireless networking is part of the furniture these days but the zoo of standards still baffles the non-specialist. This can in part be put down to the 802.11 wireless LAN working group, which has 250 supporting companies, 650 active members and an engineer's love of incomprehensible acronyms. However, with the onset of activity in personal and wide area wireless networks, the wireless LAN world has settled down and the following list of standards will probably be the last you'll need in the world of 802.11... 802.11 The original 1997 2.4GHz wireless Ethernet standard, running at 1 or 2Mbps. As with modems, newer standards can fall back to this standard under difficult conditions or if in contact with an older interface. There were two variants, frequency hopping and direct sequence, but for political rather than technical reasons. 802.11a 55Mbps in the 5GHz band. Same speed as 802.11g close up but gets slightly slower as the distance increases. The standard is fixed but regional implementations in Europe are still under discussion. Although not quite as good as 802.11g on paper, in practice it's likely to be as good or better - if only because the 5GHz band has far fewer competing users. 802.11b 11Mbps in the 2.4GHz band, the first wildly popular standard and still by far the most used. For a while, it was also known as Wi-Fi, but now 802.11g and 802.11a are also known by that name the branding is less useful. Wireless hot spots, domestic wireless broadband gateways and company WLANs are nearly 100 percent 802.11b in early 2003. 802.11c Modified 802.1d — MAC level bridging — to include 802.11 frames, thus helping with quality of service and filtering issues. Done and dusted, this is a useful standard of no interest to anyone not designing wireless LAN hardware. Be glad it's there, and move on. 802.11d Global harmonisation group. Different countries have different parts of the 2.4 and 5GHz bands available for unlicensed wireless networking. 802.11d seeks to help create standards that will be approvable in as many different countries as possible. 802.11e Quality of service (QoS) initiative for MAC level issues. In brief, allows packets with specific requirements for transmission delay and bandwidth to be passed preferentially to those with laxer needs. This will let streamed audio and video work better. When finished and available, it'll work with existing cards: end of 2003 looks possible. 802.11f Inter-access point roaming protocol. Will let you move through a wireless LAN with multiple access points from different manufacturers and maintain your connection. Not finished yet: may be available by the end of 2003. 802.11g 55Mbps in the 2.4GHz band. Downwards compatible with 802.11b. As of early 2003, you can buy '802.11g' cards despite the standard not being finished until later this year: interoperability between vendors and aspects of 802.11b compatibility being most problematic. 802.11h H is for Hiperlan - the European standard wireless LAN. This doesn't really exist, so 802.11h adds some features to 802.11a to make it suitable for European use and be Hiperlan. These features are frequency and power management to make sure that 802.11a networks don't interfere with radar and satellite services, although it's unclear whether users will reliably set these up. 802.11i The next level of security for 802.11. It includes key management and distribution, encryption and authentication. When finalised in late 2003, it will probably run on existing systems through a firmware upgrade, if perhaps not at full capability. 802.11 IR 802.11 for infra-red. Developed at the same time as 802.11 itself, and supporting 1 or 2Mbps, it was then and is now a technical oddity. No products have ever been known to support this standard, and it hasn't been developed to higher speeds. Optical LANs are available but have proprietary standards and have little advantage to radio alternatives other than nominally higher security. Good for geek pub quizzes, though. 802.11j An equivalent of 802.11h for the Japanese regulatory environment. 802.11k A recently started project to standardise the way 802.11a, b and g networks report measurements of radio and network conditions to other parts of the network stack and new applications. Should be good for network management, fault finding and other diagnostic fun. 802.11m A collection of maintenance releases for 802.11 as a whole. Internal IEEE housekeeping. 802.11x Journalistic shorthand for any 802.11 standard. Means the person concerned couldn't be bothered to type 802.11a/b/g. Rupert Goodwins is the Technical Editor at

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