Professor
Mr. Louis Voit
Semester
Spring 2007
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Today's Wi-Fi gear has limited range, is highly susceptible to interference
from cordless phones and other wireless devices, and is much slower than
old-fashioned Ethernet. All this is set to change with the advent of 802.11n.
The 802.11n standard is still being ironed out, and the IEEE, or Institute of Electrical and Electronics Engineers, isn't expected to have a final ratifcation of the standard until late
this year. However, products based on competing versions of 802.11n's powerful
smart-antenna technology, called MIMO, are already on store shelves. MIMO
stands for multiple input
multiple output and allows a wireless device to make more efficient use of data transmissions in indoor environments. The new 802.11n will include some version of MIMO, and it promises to deliver faster throughput than Ethernet and double the range of today's Wi-Fi gear |
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There's still some debate, mostly vendor infighting, about what actually qualifies as MIMO, but basically this technology uses multiple antennas to maximize throughput in a range of indoor environments. Until recently, indoor environments have a posed a serious challenge for wireless networks. Reflections off of metal furniture or construction materials in homes and offices often lead to what radio engineers call a multipath scenario,
a situation in which multiple transmission paths of the same data in a wireless
broadcast begin to interfere with each other, degrading network performance and
shrinking the coverage area of your network. Other sources of interference,
such as cordless phones, microwave ovens, baby monitors, and neighboring
networks, also pose problems for standards-based Wi-Fi gear and leave your
network with poor range or even intermittent loss of connectivity. MIMO aims to
change all that by using multipath to its advantage. The smart antennas on a
MIMO router can hand off reception and transmission dynamically to each other,
adjusting for the clearest data path on the fly. This increases both range and
throughput at any given distance in an indoor setting, especially in multipath
or interference-prone environments. |
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Unfortunately, what you currently stand to gain with so-called MIMO gear comes at the cost of poor interoperability across vendors and no guarantee of full forward compatibility with the 802.11n gear of the future. Because products are based on proprietary solutions, not a ratified standard, mixing and matching gear across vendors typically results in degraded performance. Also, when 802.11n becomes a reality, today's Pre-N/MIMO solutions probably won't be fully interoperable with gear based on the ratified spec. Interoperability problems can come back to haunt you down the road when you start adding newer standard-compliant equipment. Still, today's MIMO-enhanced gear shows us what we can expect from Wi-Fi in the not too distant future. With fast speeds, long range, and strong resistance to interference, 802.11n gear may finally deliver on the promise of home entertainment networking. |
See PC World's:
Wireless Routers Chart
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