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802.11n wireless LAN draft fails to advance

The draft IEEE 802.11n wireless LAN standard failed to move forward on a vote this week. Adversaries on the IEEE’s 11n task force quickly issued dueling interpretations of what the failure means.

According to Airgo Networks, the lack of support means the group’s members recognize the “desire for significant changes to the draft.” But rival chipmaker Atheros Communications asserted, “A ‘no’ vote at this stage does not indicate that there will be radical change to the standard.”

Both at least agree that the standard remains on track for final ratification by the IEEE in mid-2007.

The Draft 1.0 document was accepted by the 11n group in March by a 87 percent majority vote. Then the task group began accepting comments and recommendations for changes. This week, according to Airgo, only 46 percent voted in favor of moving the draft to the next step of the review process.

Procedurally, the vote has little effect on the current work of actually studying the submitted comments and figuring what should be done about them. But the efforts to influence how people view the emerging standard show how much the chip vendors have at stake.

Airgo was the first company to introduce a commercial radio chipset that uses multiple-input multiple-output (MIMO) technology. That silicon is now in its third generation. Wireless LAN vendors such as Belkin, Linksys, and Netgear have access points based on the Airgo chips, aimed at the home and SOHO markets. But Bluesocket and Taiwan-based laptop OEM Asusa have just announced, respectively, an enterprise access point and a wireless high-end laptop that use Airgo’s third-generation chip.

Airgo has a huge lead over rivals such as Atheros, Broadcom and Marvell. All three announced their first MIMO chipsets when the 11n draft was adopted. All three describe their silicon as being compliant with the draft 11n specification.

But the first products based on these early rival chips are being received with tepid reviews. A benchmark test of five MIMO products in a rented home, performed by wireless consultancy The Farpoint Group, Ashland, Mass., found that the Airgo-based Linksys SRX400 access point delivered higher throughput over longer distances than four other products, one using Marvell silicon, the other three (including another Linksys product) using Broadcom.

Interoperability among the various brands of access points and client cards was also disappointing, according to Farpoint Principal Craig Mathias. “In no case could we get any heterogeneous combination of the ‘draft compliant’ clients and [wireless] routers to connect at more than typical 11g (20-24Mbps) rates,” he wrote in the test report.

“While we were not surprised with the obvious immaturity of the ‘draft compliant’ products, our expectations were frankly higher. Range-vs.-throughput performance was relatively poor, security implementations need work, and the interoperability implied by [the term] ‘draft compliant’ seems to be missing.”

Airgo’s rivals have promised that their first-generation “draft n” chips will be upgradeable to the final 11n standard via new firmware. That’s a claim that analysts like Mathias are skeptical of, and that Airgo executives deride.

“We might feel more comfortable with the ‘draft compliant’ products if we believed that subsequent firmware and/or software upgrades would indeed result in significant improvement in either or both of performance or compatibility,” Mathias wrote.

Airgo CEO Greg Raleigh says significant changes to the draft should be made. He singles out the need to improve interoperability between the 11n products and the vast numbers of existing WLAN access points and clients. He asserts that this week’s vote is evidence that most 11n group members agree, and are willing to make those changes in the next draft.

But Atheros counters that the vote outcome this week was widely expected, and is simply a normal part of the any IEEE review process. “In the history of all 802.11 standards, it is extremely rare for a first draft to succeed in its first letter ballot,” according to the Atheros statement.

Further, the statement quoted Atheros CTO Bill McFarland as saying, “Any changes to the draft must receive 75 percent approval in order to be included in the draft. The bar for the final 802.11n standard is set very high and we will go through several more ballots.”

The questions still on the table are whether the recommended changes will benefit users, whether the task group will incorporate then in the draft, and what impact those changes will have on the ability of chipmakers to match Airgo’s success so far.

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