802.11i

802.11g

802.11b hardware has been with us since 1999, and now, in early 2003, its maximum 11 Mbps data rate is looking smaller and smaller all the time. 'Gigabit Ethernet' (sometimes called 1000-Base-T) is starting to appear in new computers and network interface controllers, providing a billion bits per second through the network, rather than 802.11b's measly 11 million. People have long been demanding faster bit rates- the question is how to get there. Moving to 802.11a hardware provides a maximum bit rate of 54 Mbps, but it's not backward compatible with 802.11b, and moving to 802.11a requires that you replace all of your wireless hardware before any of it will work at faster speeds.

In the fall of 2000, the IEEE created a task group called 802.11g to devise a faster version of 802.11b, while preserving backward compatibility with 802.11b within the 2.4 GHz band. An 802.11g client will communicate with 802.11b access points, though at the lower bit rate supported by 802.11b. When communicating with other 802.11g devices, an 80211g device will communicate at up to 24 Mbps- more than twice the speed of 802.11b.

The stakes here are high, with billions of dollars in chipset orders on the table, so the standards process has been complicated by warring factions in the industry. Texas Instruments and Intersil have fielded competing proposals, some of which go beyond the original specified speed of 22 Mbps. Intersil demonstrated bit rates of 54 Mbps in the 2.4 GHz band, which would put 802.11g at bit rate parity with 802.11a, while retaining backward compatibility with 802.11b. Texas Instruments has 802.11b+, a 22 Mbps proprietary extension to 802.11b on the market now (and used in product lines like D-Link's AirPlus) but it is not compatible with the 802.11g proposal and will not 'talk' at its full speed to gear other than units incorporating the same TI chip set. (It will, however, communicate with standard 802.11b gear at 802.11b rates.)

At times it came down to arguments over how voting should work in choosing between the two competing companies' technologies.

As I write this in the first half of 2003, 802.11g has still not been completed nor ratified, and there are regular announcements of companies 'jumping the gun' with chipsets and even finished products supporting the current draft standard. Both Linksys and D-Link are shipping products that support the 802.11g draft standard, but I caution you that 'draft' still means 'draft,' and the final 802.11g standard may cause incompatibilities between these early 'draft' g products and later products created to the final version of the standard.

My guess is that eventually the arguing will stop and we'll have a standard for higher-speed wireless networking on 2.4 GHz, with backward compatibility to 802.11b. But given the crowding on the 2.4 GHz band and the big head start that 802.11a has, many wonder if 802.11g will ever gain significant market share. It's still too early to tell.



Jeff Duntemann's Drive-By Wi-Fi Guide
Jeff Duntemanns Drive-By Wi-Fi Guide
ISBN: 1932111743
EAN: 2147483647
Year: 2005
Pages: 181

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