Atheros’ Align: Does Single Stream 802.11n Really Help?

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Tim Higgins

I’ve been thinking a lot about Atheros’ new Align chipsets that were announced Monday since getting an advance briefing a few weeks ago. And I’ve reached the conclusion that Align has the potential to add to the confusion that wireless networking buyers already have over draft 11n, with little benefit to consumers over current solutions.

Atheros’ primary pitch to product makers is basically: "Why continue to use old WLAN technology (802.11g) when you can future-proof your product for the same price?". Atheros isn’t disclosing chip pricing, but says that Align will enable manufacturers to sell draft 11n products for the same price as 11g products.

My guess, however, is that the real pitch is improved margins for manufacturers from using single-stream draft 11n. By keeping a slight pricing premium over 11g products, but a lower material cost than current draft 11n products, manufacturers can keep a little more and live to fight another day.

But two-stream draft 11n products have already crossed into 11g pricing space. For example, D-Link’s least expensive draft 11n router, the DIR-615, is currently available for as little as $40. While the lowest price for Linksys’ flagship 11g router, the WRT54G2, is $46.

And while I haven’t yet seen any draft 11n routers that match the current $20 pricing of products like Netgear’s WPN824 and Trendnet’s TEW-432BRP, there are bargains to be had for draft 11n routers, such as Netgear’s WNR834B (refurbed for around $40). Are Align-based products really going to be cheaper than these entry-level draft 11n bargains that are already out there?

A Stream of Confusion

If you’re like me, you thought that MIMO (multiple-input multiple-output) technology is a key component of 802.11n. This Wi-Fi Alliance white paper explains that "MIMO employs a technique called spatial multiplexing to transport two or more data streams simultaneously in the same frequency channel" and goes on to say that "spatial multiplexing is central to 802.11n and has the potential of doubling the throughput of a wireless channel when two spatial streams are transmitted".

But, bowing to pressure from mobile product makers, the IEEE included a single-stream, i.e. non-MIMO, variant in addition to the 2, 3 and 4 stream forms in 802.11n. Those companies were concerned that there wouldn’t be enough room in products to support the multiple receivers, transmitters and particularly, antennas, required for multi-stream products.

When the Wi-Fi Alliance put together its requirements for draft 2.0 certification, however, it declared that "spatial multiplexing capability is mandatory for Wi-Fi CERTIFIED 802.11n draft 2.0 products, except for handheld devices [italics mine]. Certification requires that least 2 spatial streams must be supported". In other words, single stream access points and routers can’t be Wi-Fi certified, but client devices can. (For more on this, see One if by STA, Two if by AP. A Draft 802.11n Certification Oddity.)

I asked the Wi-Fi Alliance whether they had changed their position on certification of single-stream AP’s and routers in light of Atheros’ announcement and found that, at least for now, they haven’t. The Alliance said that its 11n task group is "still evaluating which features/capabilities will be supported and which won’t, and 1×1 capabilities are on the radar". But, for now, there is "no official change in the 802.11n draft 2.0 program".

So why would Atheros invest a lot of time and money in a product that currently can’t be Wi-Fi Certified for draft 802.11n and say that a key goal of the product is to accelerate the transition from 802.11g to 802.11n? Who would buy such a product?

It turns out that people already have… and from the biggest name in networking—Cisco.

Cisco used the first single stream chipset family—Ralink’s R2700 1T2R that was announced last year—to launch its now discontinued Linksys WRT100 and its replacement, the WRT110. As I write this, both can be had for around $45.

Neither of those products claims to be draft 11n compliant, and Cisco / Linksys (perhaps wisely) sidestepped the single-stream issue by slapping a "RangePlus" moniker on its Ralink-based single-stream products and referring to MIMO in its marketing material, not 802.11n. This apparently worked, because Cisco is now in its second generation of the RangePlus line.

Does Anyone Care?

So, to sum up, we have a major (if not the leading) manufacturer of draft 11n chipsets on a big push to help manufacturers ship higher margin, but not necessarily lower-priced draft 802.11n compatible products that can’t currently be Draft 2.0 802.11n certified by the Wi-Fi Alliance. The question is, should you buy them?

Actually, in the case of note and netbooks and other wireless clients, you don’t have to worry. Embedded or add-on Align-based WLAN cards will be Wi-Fi Certifiable, just like current dual-stream designs.

As for wireless routers and APs, we’ll have to wait and see. Will manufacturers go the Cisco route; stay away from the "802.11n" word and create a new class of "plus" products that are 802.11g Certified (thus getting the Wi-Fi Certified mark on the box, but leaving it to the consumer to check for the "N" cert.)?

Or will they just throw another suffix or prefix next to "Wireless N" on the front of the box, omit any reference to draft 802.11n, throw it out into the market and see if it sells?

In either case, it seems like the rise of single-stream routers threatens to weaken the value of draft 11n Wi-Fi Certification, which is the main thing that got us to the level of interoperability and compatibility among draft 11n products that we see today.

If the Alliance doesn’t move quickly to bring single-stream APs and routers under its tent, then we’ll quickly be back to where we were in pre Draft 2.0 days. And if you can’t remember back that far, trust me, we don’t want to go back there.

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