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Fast Forward by Rob Pegoraro

WiFi Shifts Into a Faster Gear

By Rob Pegoraro
Sunday, April 17, 2005; Page F07

The alphabet soup of wireless networking -- a dish that most users learned to digest only in the past couple of years -- is getting a few new letters. This latest addition to the recipe promises faster data transfers over wider areas for your home computers, but it comes with a catch: It's based on a standard that, technically speaking, doesn't exist yet.

This new crop of WiFi devices goes by a couple of names -- "MIMO" (short for "multiple in, multiple out," pronounced "my-mo") and "Pre-n" (which refers to the "802.11n" protocol that's still well over a year from being finished). Their differences are more marketing than anything. Since so many people in the industry expect 802.11n to be built on MIMO technology, some employ the term "Pre-n" to imply that their products are closer to that future -- even when they run on the same basic third-party chips as the merely-MIMO hardware of other firms.

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To confuse things just a bit more, vendors will sometimes use their own brand names, such as "RangeMax" and "SRX," instead of either term. (For now, I'm sticking with MIMO.)

By any name, all of these devices offer the same mix of benefits and risks: By using more than one radio signal at once and using special software to shepherd these overlapping transmissions, they can vastly exceed the maximum speed and range of current WiFi. (They all support the established 802.11b and 802.11g WiFi standards.)

Based on what I saw in testing MIMO hardware from three vendors, Belkin Corp., Linksys and Netgear Inc., this technology does deliver on those promises, especially in terms of range. But they cost between two and three times as much as standard WiFi gear, and many users won't get any benefit out of the added performance the high price brings. Plus, every user tempted by the lure of getting a jump on the next big thing in wireless should first ponder the chance that the purchase could turn into a pumpkin later on.

For my tests, I borrowed a MIMO access point and a PC Card laptop adapter from each manufacturer: Belkin's Wireless Pre-N Router ($160) and Wireless Pre-N Notebook Network Card ($110); Linksys's Wireless-G Broadband Router with SRX ($199) and Wireless-G Notebook Adapter with SRX ($129); and Netgear's RangeMax Wireless Router ($149) and RangeMax Wireless PC Card ($99). Then I checked to see how fast these combinations of hardware could send files and how far they would let me roam with a laptop.

The ads for this genre of devices suggest they'll have you blasting files back and forth at more than 100 million bits per second (Mbps), faster than most wired networks. But MIMO, like every other kind of WiFi, loses most of that potential to interference and overhead. That's why my existing 802.11g WiFi network at home, which must pass through a floor and a plaster wall or two, can ship a file at about five Mbps via standard Windows file sharing -- about a fourth of its theoretical peak performance. The MIMO devices, tested under the same conditions, ranged from 13 to 23 Mbps, or about a fourth of their theoretical peak.

The Belkin combo ran the slowest, at about 13 Mbps; Netgear performed at 15 and 19 Mbps in success tests; Linksys did best, at 21 and 23 Mbps. When I mixed and matched different brands of access point and receiver, the access point broadcasting the signal determined the overall speed -- the Linksys unit remained the fastest even when linked to a Belkin or Netgear receiver.

Those speeds will save you time when shuffling large files from one computer to the next, but they're probably not quick enough for reliable video sharing -- much less using a wireless network to beam an HDTV signal from room to room.

And if you need to share only a broadband Internet connection throughout your home, even the oldest flavor of WiFi, 802.11b, is more than fast enough.

The MIMO technology in these companies' access points delivered a much bigger benefit when I tested the reach of their signals. With my old 802.11g access point, a Dell Dimension laptop with an Intel Centrino 802.11g receiver could go no farther than about 40 yards.

Popping each MIMO receiver into a test laptop's PC Card slot made a huge difference. The Netgear receiver and access point combined for a 75-yard range, while the Belkin and Linksys hardware each hit about 100 yards. (Two out of three times, Belkin's receiver appeared to crash the test laptop once it lost the signal.)

Better yet, I saw the same range using that Dell laptop's existing receiver. Even an old IBM ThinkPad with just an 802.11b receiver lengthened its leash with a MIMO access point -- 50 yards instead of the 20 it managed on an 802.11g network.

But there's one problem with those figures (well, besides the fact that it's impossible not to look like a kook when you hold a laptop open while slowly walking down a street): How many people actually need to use a laptop 100 yards away, or even 50?

The biggest issue with all these products, though, is their long-term compatibility. Although the Belkin, Linksys and Netgear devices all worked with one another (with some tinkering), the same can't be said for products to be built on the final 802.11n standard. Because that set of rules is so far off in the distance, none of these manufacturers will make any guarantee that the products can ever be upgraded to it.

The risk is not that a MIMO device will self-destruct when 802.11n hardware shows up on the nearest store shelves -- it's that future devices will send data still faster and farther. MIMO or Pre-n devices will wind up looking more like souped-up 802.11g gear.

Until that picture gets settled, consider a couple of cheaper ways to solve the problems that MIMO aims to tackle. A too-slow network can be accelerated by replacing an 802.11b access point with one that uses 802.11g; a "g" network, in turn, can get a further speed boost by upgrading any "b" laptops to use "g" receivers, then switching the network to run in 802.11g mode only.

As for distance, adding a second 802.11g access point and setting that to run as a repeater may patch any holes in your network for $50 or so.

Only if those two measures don't work should you consider upgrading to a MIMO setup -- and even then, start with just a MIMO access point, since it should offer about the same coverage boost with your existing hardware.

The risk attached to buying a MIMO product should decline over time, as the 802.11n standard gets closer to the finish line. But while they continue the patient work of testing and improving this technology, I'd like to suggest another area in far more desperate need of work: the awful setup programs these companies inflict on their users, which continue to throw around jargon heedlessly while making it far too easy to leave a network wide open to the public. Fixing those problems would improve WiFi far more than adding yet another letter to the wireless alphabet.

Living with technology, or trying to? E-mail Rob Pegoraro at rob@twp.com.


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