On 24 Oct 2004 19:06:17 -0700,
(E-Mail Removed) (Allen Benusa)
wrote:
>Hmmm... those claims are somewhat interesting. Supposedly they are
>able to do it with multiple antennas. Actually the 800% more coverage
>is based on square area, not linear distance. So if your original
>radius was 100 ft, PI*100^2 = 31,415 sq ft. So if a radius was 282.8
>ft, PI*282.8^2 = 251,327 sq ft. 8X (800%) coverage achieved with a
>radius of 2.8X the original.
>- Allen -
That's one way to look at it, where coverage area doubles for every
sqrt(2) increase. An easier way is that coverage area doubles for
every 3dB increase in system gain. Therefore, an 8x increase in
coverage area corresponds to a 9dB increase in system gain. This
assumes everything else is constant such as modulation type, data
rate, error rate, tx power, rx sensitivity, antennas, etc.
Bob didn't mention if the 800% increase in coverage was mutually
exclusive with the 600% (6x) increase in speed. Usually, range and
preformance are interdependent and mutually exclusive. For example,
using the stock antennas, 802.11g will deliver about 30Mbits/sec
thruput, but only up to about 15ft away. Any furthur range implies
either a drop in thruput, or an increase in system gain through
improved antennas.
Notice that the "600% faster transmission" does not specify in
reference to what benchmark. Faster than what? If it's faster than
802.11g at 54Mbits/sec, then 6x would be 324Mbits/sec, which is faster
than the 100baseTX ethernet interface can handle running at wirespeed.
If true, 6x will require the use of a gigabit ethernet interface.
Although enchanced mutations of 802.11g advertise 108Mbits/sec
"performance", I have yet to see anything close to 108Mbits/sec
delivered on the bench or reported in the field. I expect MIMO to be
much of the same hype (or worse).
Also, since there are multiple implimentations of MIMO applying for
802.11n standardization, the IEEE and WI-FI committee are not
particularly thrilled with premature announcements:
http://www.eweek.com/article2/0,1759,1676691,00.asp
http://www.eweek.com/article2/0,1759,1674640,00.asp
http://www.eweek.com/article2/0,1759,1624990,00.asp
Ignoring the hype, the advantage of MIMO is the ability to use
multiple independent paths to deliver data. That means hogging the
entire 2.4GHz band, and utilizing reflections to a much greater degree
than OFDM. My guess(tm) is that it will be no better than some of the
proprietary 802.11g enhancements at short range (due to bandwidth
limitations) and significantly better bandwidth in a high reflection
(office) environment due to a reduction in bit error rate in a
multipath environment.
>
>"Bob Alston" <(E-Mail Removed)> wrote in message news:<PIUed.113224$Lo6.37751@fed1read03>...
>> Anyone got one of this working yet? Apparently Comp_USA has 'em.
>>
>> Not 802.11n but one of the possible configurations. Belkin is quoted as
>> claiming 800% wider coverage and 600% faster transmissions, max at about 100
>> Mbps.
>>
>> --
>> Bob Alston
>>
>> bobalston9 AT aol DOT com
>>
>>
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Jeff Liebermann
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