And to further add to what Jack said:
When you are tying to factor indoor coverage, there are soo many things
to
consider. Building construction is the big one. If they have metal siding on
the house or if it is stucco laid over a wire mesh, the signal will be
almost dead inside unless some of it sneaks in through the widows. Now if
the windows have metallic tint on them that creates problems too. Add the
attenuation of multiple walls and/or the possibility of a client location in
the basement and you can see the pitfalls of planning indoor coverage
(especially over a large geographic area). I would say that adding only 3 dB
to get indoor coverage will be way to low..... Think back to the days of
analog cellular, when you could hear the signal fades and how you had to
move around inside a building to get a good call. That was at 800 MHz, go
higher in frequency and the signal gets absorbed a lot more by building
materials. It's really a nightmare to try and plan for, especially in the
unlicensed spectrum.
Thank You,
Brian Webster
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jack Unger
Sent: Friday, September 26, 2008 5:05 AM
To: [EMAIL PROTECTED]; WISPA General List
Subject: Re: [WISPA] Cisco on calculating RF values
Rogelio,
The Cisco website seems to be down at the moment but RF is still RF and
it behaves the same way indoors as it behaves outdoors except of course
if there are more obstructions indoors than outdoors.
In that case, then yes, depending on the nature of the obstructions,
more power would be necessary at both ends of an indoor link to have
same bidirectional throughput and reliability as an equivalent-length
link outdoors. A 6 dB power increase doubles the link distance. Doubling
the LINK DISTANCE from/to an access point (assuming an omnidirectional
antenna on the AP) will make the COVERAGE AREA four times larger
(because the area of a circle is pi (3.14) times the radius of the
circle squared).
To simply double the coverage AREA of a circle (as opposed to doubling
the DISTANCE of a link) would then take something less than 6 dB
(assuming no obstructions and assuming a straight linear decrease in the
peak number of sunspots that first appear during the time frame between
the waxing and the waning moon in the month of December of every third
even year after 1776).
jack
Rogelio wrote:
> I found this URL while googling for more info on Brian Webster's
> response to my 4.9 question (on why smaller channels were more efficient).
>
>
http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a0080
0e90fe.shtml
>
> I was wondering if 9db was the amount of wattage others here found was
> amount necessary to double indoor coverage (as opposed to 6 db for
> outdoor coverage).
>
>
>
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--
Jack Unger - President, Ask-Wi.Com, Inc.
Serving the Broadband Wireless Industry Since 1993
Cisco Press Author - "Deploying License-Free Wireless WANs"
NEXT ONLINE TRAINING OCTOBER 8th & 9th <http://www.linktechs.net/askwi.asp>
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Phone 818-227-4220 Email <[EMAIL PROTECTED]>
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