landuchi <(E-Mail Removed)> hath wroth:
>If i have to install a wired network i can look at several standars like
>EIA/TIA 568 and they will tell me how the work should be done (cable
>lengths, cable terminations, maximun tension aplied during instalation
>and so on.) but when talking about wireless networks things are not so
>clear.
Not exactly. BISCI is now certifying wireless contractors as well as
wired. See:
<http://www.bicsi.org/Content/Index.aspx?File=wdoverview.htm>
I've been tempted to get certified because the local hospitals are
looking for ways to irritate their contractors and are asking for
wallpaper.
>Are there similar standars for wireless networks ?
Not that I know of. The reason is that much of the LAN wiring
installation standards are based on the NEC (National Electrial Code)
sections on "signalling" cabling. The primary interest is that the
contract not do anything unsafe, in the eyes of the building
inspectors, fire inspectors, or insurance companies. Since wireless
(and fiber) are inherently fireproof and electrically safe, there are
no safety standards. The only ones close are the FCC RF exposure and
safety standards.
>Can i certify a wireless network ?
Certify to what standard? The Wi-Fi Alliance certifies the equipment,
but not the installers, installation, or system.
<http://www.wi-fi.org/certification_programs.php>
>What specifications would my wireless network need
>to comply with in order to be certified ?
- IEEE 802.11a/b/g
- Wi-Fi.org equipment certification
- Firewall certification. For example by ICSA:
<http://www.icsalabs.com>
- FCC Part 15 (incidental and intentional radiation)
- Electrical and fire safety standards (UL, etc)
If you look at the huge number of logos on the serial number tags,
you'll see most of the electrical certification tags.
>- Which should be "standard" distance between access points ?
>- What SNR is considered to be correct ?
Those are inter-related. Very basically, for a given arrangement of
locations, radios and antennas, you can trade:
- data rate (or thruput)
- distance
- error rate (SNR)
for each other. The goal is to maximize the "fade margin" or SOM
(system operating margin) at some value that will insure reliable
operation. The relationship between reliability (or rather uptime) is
directly related to the fade margin. 20dB fade margin is a good
*MINIMUM*. See the FAQ at:
<http://wireless.wikia.com/wiki/Wi-Fi#Link_Calculations>
Even more crudely, it doesn't matter how far or how fast as long as
you have an adequate fade margin (at the speed and distance).
--
Jeff Liebermann
(E-Mail Removed)
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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