Including the basement, our house is about 3,000 square feet, but even in the farthest point from the MIMO router, I have no connectivity problems and no drop-off in download speeds. In fact, Belkin claims good connectivity over 250,000 square feet (the fastest current version of Wi-Fi, 802.11g, generally covers less than one-fifth that), so I could probably read e-mail while mowing my lawn, if I felt like it. And the MIMO notebook card works fine in the local coffee shop, using the existing Wi-Fi standard.
In short, MIMO looks to be a good thing for people and businesses whose connectivity is spotty and unreliable or who experience slow data transmission for PCs at the extreme ends of their current Wi-Fi networks’ reach. That’s nice, but the importance of MIMO goes far beyond improving the performance of Wi-Fi. It is, in fact, “the most significant radio technology ever,” claims wireless consultant Craig Mathias, principal at the Farpoint Group in Ashland, MA. The reason for such excitement is that MIMO appears to be an excellent answer to a wireless problem that’s existed since Marconi.
“In wireless communication, the biggest problem has always been multipath interference – signals taking different paths and canceling each other out or blurring the signal,” explains Ira Brodsky, president of Datacomm Research in St. Louis. The result of this interference is familiar to anyone who’s ever had trouble tuning in a station over a car radio: signal drops – the very thing wireless networks must be engineered to prevent.
MIMO is designed to turn this inherent problem with wireless into an advantage. In a sense, MIMO is to wireless what multiprocessing is to computing – a way to move data faster by sending it through multiple channels. Each of the radios on the MIMO chipset pulls in a signal, and all the signals are then run through digital signal-processing algorithms and re-formed into a single transmission. This use of redundant multiple signals allows MIMO to increase the reliability and range of transmissions. Indeed, the strategy is widely applicable, and over the next several years, MIMO technology may make its way into cellular networks and products that might benefit from wireless transmission, like camcorders and televisions.
The exact origins of today’s MIMO technology are disputed, which seems fitting, since there is no agreement on its exact definition, either. There are various versions of the technology with such esoteric names as “spatial diversity multiplexing,” “beamforming,” “antenna diversity,” and “channel beaming.” What is clear is that Airgo, headed by CEO Greg Raleigh, who as a graduate student at Stanford University in the 1990s helped pioneer MIMO, is the first company to come up with a version cheap enough to make it onto the consumer market.
Adding to the confusion around MIMO is that it is to be the basis for the IEEE’s 802.11n standard, which is not yet a standard and is not expected to become one until at least 2007.
The bottom line for consumers? People who buy MIMO products before 2007 will eventually have to buy new products to get the full speed advantages of the technique when the standard has finally been finished, predicts Robert W. Heath, an assistant professor in electrical and computer engineering at the University of Texas at Austin. Still, if MIMO keeps improving, it might be well worth it.