Draft N: Caveat Emptor
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Did you rush out and buy new products for your home network this month, based on the draft of the 802.11n standard? If not, you may want to wait. The first reports on the performance and interoperability are not ringing endorsements.
Craig Mathias of Farpoint Group states that in initial tests, the "Draft N" products could not communicate with each other when in the high-speed MIMO (multiple in, multiple out) mode used by 802.11n. There was no interoperability when the competing products had the same chip, nor even when the products were from the same vendor.
But if you dummy everything back to 802.11g speeds, you're fine.
Concerns about the products have prompted editorials saying Don't Buy Draft N (that from Wi-Fi Networking News). The reasons stated include the lack of a guarantee on upgradeability, possible interference with existing WLAN equipment, the need for Gigabit Ethernet to get the speed benefit, and the current expense of the equipment.
Home networking products using Draft N, mainly wireless routers around $150 and PC Cards for notebooks for about $120, have dribbled into the retail and online market already from Netgear, Buffalo Technology and Linksys. Products from D-Link and Belkin aren't far behind.
Mathias did his tests at a rented residential house, checked it with a spectrum analyzer to find unused RF space, and tested range and throughput with the free Iperf benchmarking tool. The products were set up with out-of-the-box settings, changed only to turn on WPA2 encryption.
The best performance he found was in the Linksys SRX 400 line of products which aren't even based on the 802.11n draft. They came out months ahead of the recent ratification of Draft N 1.0. In his report, Mathias said that with the SRS 400, which uses 3rd generation True MIMO chips from Airgo Networks, Linksys was "free to focus on absolute performance" in the product line, since it wasn't worried about meeting an industry specification.
The lack of interoperability of any of the products using draft N "seems to indicate that 'draft compliance' is either poorly implemented or missing altogether," the report states.
Mathias told Wi-Fi Planet that he would not recommend that anyone buy Draft N products. "I have an issue with 'Draft N' that's a bogus claim," he said. "There's no such thing as 'Draft N;' you can't be compliant with a draft. It says on the cover [of the draft specification], 'not to be used for conformance or compliance purposes.'"
Broadcom, which makes the the Intensi-Fi chipset used in the Buffalo and Netgear products tested by Mathias, blames the bad interoperability results a feature it specifically ensured in an Intensi-Fi announcement this week as the result of getting some pre-production drivers with the equipment. Mathias purchased the products at retail, however; he did not get them directly from the vendors.
"They weren't intended for the [retail] channel," says Bill Bunch, Product Manager for Broadcom's Intensi-Fi chips. "There were some pilot errors somewhere. I don't know where it occurred."
He says Broadcom's internal testing with samples from its vendor customers have worked perfectly. Tests with products using chips from other vendors are under non-disclosure, he said, and could not be specific. He said only that "with any given implementation, whether they'll talk to Broadcom [based products] is a question of whether its a specification issue or a driver issue."
Broadcom, along with Marvell, Atheros, and Intel, helped push through the 802.11n draft earlier this year via a consortium called the EWC. Many viewed it as an attempt to undermine the momentum of MIMO chips from Airgo.
Airgo continues to enjoy success today with its True MIMO products. The company says it has 17.4 percent of the retail revenue market share in Wi-Fi routers, according to NPD data. It just announced deals to power USB 2.0 Wi-Fi adapters to come from Netgear and Linksys, again using the 3rd Gen True MIMO chip.
Bunch is quick to point out that getting to a draft of 802.11n in the IEEE was the result of a unanimous vote, which is not something even 802.11g could garner years ago.
In the end, issues with the products may come down to the marketing claims.
Glenn Fleishman of Wi-Fi Networking News said in his editorial, "These companies are shipping Draft N devices for the bragging rights to be first out of the gate and to try to brand their Draft N products identities on consumers minds. Theres no good technical reason to release these products this early."
Mathias told us, "I wouldn't say [vendors are] trying to screw people, I wouldn't go that far, but they are looking for marketing advantage in the wrong place. Compete on price, performance and features not on compliance that can't be verified... it's just not right."
His advice so far he'll be doing more tests as more Draft N products emerge is to stick with the Linksys SRX 400 products: they're still the fastest, and they work very well with 802.11g.
eWeek performed tests on the new Linksys Wireless-N products also using the Broadcom Intensi-Fi chips and said that, while they're faster than anything they've seen yet in Wi-Fi, investing in the products is unadvisable due to the issues with legacy networks.
Airgo is, of course, delighted and vindicated by the findings.
The company has not come out with a Draft N product, and says it will not do so until the standard is farther along later this year, at which time its 4th generation (to be called Gen-N) will debut. It feels that, by waiting, it is taking the high road when it comes to honest marketing to the consumer.
"We've tried for years here to be 100 percent accurate and factual about where the industry is going, what MIMO is all about," says Greg Raleigh, CEO of Airgo. "The semiconductor industry is notorious for overstatement. But the approach of our competitors is, [the fix comes with] the next software load, or don't count on this early product. At some point, they have to be held to account."
Airgo's past isn't totally innocent, either, as Belkin started selling the 1st Gen TRUE MIMO chips in products it labeled as "Pre-N" in late 2004 (though that wasn't Airgo's call). At the time, the Wi-Fi Alliance took a stance that any product that claims to have IEEE 802.11n capabilities but "adversely impacts the interoperability of other Wi-Fi Certified products" will get its certification revoked. That hasn't happened yet.
None of the products using Draft N have been certified for interoperability, not even with 11g. Not yet.
Bunch reiterates that "Broadcom is 100 percent committed to cross-vendor interoperability both by vendor and across chipsets. I'd hate to see the Wi-Fi industry, with respect to 802.11n, get a black eye from a single report. More of them going forward will show interoperability, both across brand and across chips."
As for upgradeability of the chips to the final 802.11n standard in a year or more, no vendor will come out and guarantee it for these products.
Caveat emptor, indeed.