802.11n: Compatability Crunch?

After months of infighting at the Institute of Electrical and Electronics Engineers Inc. (IEEE) over the specification of the high-speed 802.11n wireless LAN standard, Friday's vote to approve draft 1.0 seemed to be another sign that things are moving forward apace now.

As always, however, things are a little different behind the scenes. More dickering is going on about a technical issue that could be important for enterprise users looking to adopt the technology.

Chip vendors Airgo Networks Inc. and Atheros Communications Inc. (Nasdaq: ATHR) both laid out the problem for Unstrung: When the 802.11n kit broadcasts in higher power mode, it uses two channels and so can knock neighboring 802.11b/g networks out of its air space.

Atheros says that header recognition, channel cueing, and anti-collision mechanisms are already in the specification to deal with this problem. There was no agreement in this draft, however, on whether it is optional or mandatory for vendors to implement these workarounds.

"The argument is about whether it can say 'may' or 'should,'" explains Bill McFarland, CTO at Atheros.

McFarland reckons that the issue, which he descibes as "overblown," will be dealt with other the coming weeks. Cisco Systems Inc. (Nasdaq: CSCO) and Motorola Inc. (NYSE: MOT) are chairing an ad-hoc group to try and resolve the issue.

McFarland, meanwhile, is confident that the high-speed WiFi work is on the right track. "We believe that the draft will cease to have any changes made to it by the end of 2006," he says.

This would put official 802.11n product on track for launch sometime in 2007.

Despite the optimism, potential enterprise users should monitor developments on this issue. Interoperability between different WiFi standards will clearly be a big issue if users continue to update 802.11 networks in the organic fashion that we have seen so far.

And at least one analyst is less confident of future interoperability between 802.11 variants.

"I’d be surprised if -- even if they include a compatibility mode -- it could do both a/g and g at the same time," writes analyst Jack Gold of J.Gold Associates in an email. "I could see some interaction problems with n if you also want to support b/g. My guess is they are betting on equipment replacement, not necessarily backwards compatibility to existing systems." — Dan Jones, Site Editor, Unstrung

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