Faster, Farther Wi-Fi

Newly approved Wi-Fi standards should give a boost to the wireless industry -- and likely expand media in the home.

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A faster and more far-reaching wireless Internet is coming within a year or so thanks to new Wi-Fi standards approved by members of the IEEE (Institute of Electrical and Electronics Engineers). These standards will provide a framework for the next generation of wireless routers and chipsets in laptops, mobile phones, and any other wireless consumer electronic devices.
The new IEEE 802.11n standards will be exceedingly fast, transmitting at least 100 megabits of information per second, and possibly more, depending on the equipment used. That's roughly four times the current 802.11g rate of 24 megabits per second. Moreover, equipment that incorporates the new standards could extend the range of a wireless signal by 50 percent, says Bill McFarland, chief technology officer at Atheros, a wireless chip maker.
At first look, these standards may seem like a formality; but they represent a fundamental shift in the way information is transmitted over airwaves. Consequently, manufacturers, as well as other wireless experts, are excited about the prospects for 802.11n. "I don't think this is incremental," says Babak Daneshrad, an electrical engineer at UCLA. "I think this is a major step...a paradigm shift."
The technology that puts 802.11n in a league of its own, MIMO ("multiple input, multiple output"), is necessary to meet the data transfer rates and extended range dictated by the standards. MIMO routers use multiple antennas and radio systems to simultaneously receive and transmit information. The "simultaneous" part is crucial. Although some routers have multiple antennas, before MIMO, they could be used only one at a time, explains McFarland.
With MIMO, multiple, intertwined wireless signals are received, then sent through "signal processing" algorithms that untangle the data. Because MIMO equipment can handle many more data streams than traditional wireless gear, there's built-in redundancy, which augments not only the data transfer rate, but also network reliability and range.
The more antennas on a router, according to McFarland, the faster the data can be moved around. Theoretically, rates of 600 megabits per second could be achieved, but "the true throughput level is usually significantly less" because, as well as transmitting data, resources also direct the flow of data packets.
With 802.11n, the high-speed transfer will be noticeable only within the traditional range of wireless routers. Once outside that range, the transfer rate will drop to about 801.11g speeds. This will occur because of a resource trade-off in wireless networks, explains UCLA's Daneshrad. Using pizza dough as an analogy, he notes how one starts with a certain amount of dough, then can either keep the crust thick or stretch it out to cover a larger area. Similarly, "you can use multiple antennas to blast [data] at the closest distance," he says, "or you can fall back on the [data transfer] rate and give yourself range extension."
By Kate Greene

Read article at techreview.com


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