The 802.11n BluesBy Steven Vaughan-Nichols | Posted 2005-01-25 Email Print
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Pre-802.11n devices with great Wi-Fi performance are starting to appear. Unfortuntely, the standard is nowhere close to being finalized.
What's wrong with this picture? You're offered 2.4 GHz Wi-Fi setup that's both faster and has more range than 802.11g, is both 802.11g- and 802.11b-compatible and doesn't interfere with conventional 802.11b/802.11g, a la Atheros Communications Inc.'s Super-G. You'd jump at this deal, right?
Oh, it doesn't work as well as Belkin promises. 800 percent greater coverage than standard 802.11g and 600 percent greater speeds than standard 802.11g? Hardly. Try 200 to 300 percent. Still, that's darn good and when you consider that the Belkin products can deliver almost 9M bps throughput at 50 yards when typical 802.11g equipment is topping out at 1M bps, that's downright wonderful.
Belkin manages to do this by using MIMO (multiple input/multiple output) technology to improve its 802.11g devices' speed, range and reliability. They're not the only ones. Linksys, a division of Cisco Systems Inc., is using the same chip set, Airgo Networks Inc.'s True MIMO AGN100 Baseband/MAC (media access control) processor and AGN100RF transceiver for its Wireless-G Router with SRX (Speed and Range eXpansion), WRT54GX, and Wireless-G PC Card with SRX, WPC54GX.
OK, it works, so what's the problem? The problem is that Belkin is advertising this as a pre-802.11n technology and the brand of MIMO the company is pushing may or may not become part of 802.11n. If your customers want to future-proof their Wi-Fi investment by making sure that anyone's MIMO-enabled network equipment today will work efficiently with tomorrow's 802.11n devices, you have a potential problem.
There are two major sides warring over 802.11n. On one hand, you have the WWiSE (World-Wide Spectrum Efficiency) group. It's position is that 802.11n should be based on 2x2 MIMO (MIMO with 2 transmitters and 2 antennas) that operates in 802.11g and 802.11a's 20MHz-wide channels, in their respective 2.4GHz and 5GHz ranges.
WWiSE claims that with its approach, users would see higher performance, more robust data modes, and greater throughput. And, since this would be based on Airgo's existing work, WWiSE's supporters also state that this is a mature specification that could be immediately turned into a standard, thus enabling vendors to immediately get their devices to market
On the other hand, you have the TGn (IEEE 802.11 Task Group N) Sync group. They also support MIMO, but instead of using just 20MHz channels, they want to use 40MHz channels. This would have the effect of bonding together two 20Mhz channels, the trick used by Super-G, to further increase bandwidth. Thus, TGn Sync supporters claim that their technology would be scalable up to 630M bps.
Need I say that the proposed standards are incompatible and that the companies behind each one have no love for each other's proposals? Of course not.
At least two other proposals for the 802.11n standard, one from Mitsubishi and Motorola, and another from Qualcomm, which has joined forces with TGn Sync, are no longer in the running.
Still, as with 802.11g, it's clear that we're going to be spending a long time with pre-standard 802.11n devices. And, that's fine if your customers are cool with living with a technology that may prove to be a dead end.
Making matters even more problematic is that, unlike 802.11g, where many early devices could be upgraded to the real standard with a firmware upgrade, that's less likely to be the case with the pre-N MIMO devices, depending on who wins the standard war.
All signs point to the 802.11n standard battle taking its own sweet time to come to a resolution. I don't expect to see a real 802.11n standard until well into 2006.
So, the bottom line is that if your customers want bettermuch betterWi-Fi speeds and coverage today and don't care about having to possibly upgrade their wireless LAN infrastructure in two years, point them to the MIMO-enabled boxes that are now entering the channel. If, though, they don't want to face such an upgrade in only two years, you're better off just selling them on standard 802.11g gear.
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