Draft N Damage Control

By Eric Griffith

May 31, 2006

Chipmakers say early 802.11n products work together just fine; Azimuth will offer an 11n testing tool.

When the early tests of Draft N products — those using chips based on the version 1.0 draft of the 802.11n specification from the IEEE — didn't come out too favorably and pundits said not to buy them, it's natural that the chipmakers and vendors who stand to profit by making the hardware would be up in arms.

Today, Atheros Communications and Broadcom, two of the leading Wi-Fi silicon makers, announced that they've been jointly conducting tests of their Draft N chipsets to make sure they're interoperable. They claim the Atheros XSPAN and Broadcom Intensi-Fi chips can communicate just fine at speeds faster than 100 Megabits per second (Mbps). They plan to demonstrate this interoperability at the COMPUTEX show in Taiwan next week.

The companies said in an announcement that their tests "lay the groundwork for successful Wi-Fi Alliance testing when the organization's certification process is finalized."

Early tests of the initial equipment from vendors Netgear and Buffalo Technology by the Farpoint Group found the products couldn't communicate at all unless they dummied back to the baseline of 802.11g functions... and that included two different products based on Broadcom chips. (Broadcom blamed the problem on bad drivers that had gone to retail and shouldn't have.)

There are no independent reports out yet to verify what Atheros and Broadcom claim, but Wi-Fi equipment testing company Azimuth Systems hopes to push that along. Its MIMO Functional Test is now available to check the interoperability and throughput performance of Draft N products and beyond. It will also test products for backward compatibility with existing 802.11a/b/g products on the market.  

The test runs on the Azimuth W-Series platform, using various technologies to simulate devices in motion and mimic other infrastructure devices. Azimuth has scripts to do Wi-Fi Alliance Pre-Certification — pass that test, and vendors can be relatively certain they'll pass the actual Wi-Fi Alliance independent certification tests. The Alliance has started using Azimuth equipment in its labs. The MIMO Functional Test won't be out in a fully automated version until the third quarter of this year.

The 802.11n specification, which will rely heavily on MIMO (multiple in, multiple out) technology to achieve speeds higher than 100Mbps, was pushed to draft 1.0 earlier this year. Chipmakers like Intel, Marvell, Atheros and Broadcom helped push it through so they could get chips on the market, which have already been used in products from the top four consumer Wi-Fi equipment makers in North America: Linksys, D-Link, Netgear and Buffalo.  More are on the way from vendors like Belkin and US Robotics.

Task Group N, saddled with making 11n a reality, got about 12,000 comments on the 1.0 draft (about six times what was expected). While it's possible, even likely, that none of the comments could change the 11n draft substantially, wading through them may very well delay the process of moving to future drafts anytime soon.



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