Subject: [NEXTEL-1] Re: Avoiding interference 'Surprises' in unlicensed spread spectrum deployment

From: [email-masked]
Date: Thu, 29 Apr 2004 15:34:37 -0400

From:  Jack Daniel <[email-masked]
Subject:  Re: Avoiding interference 'Surprises' in unlicensed spread
spectrum deployment

This is to be expected when manufacturers sell radios in blister packs
for under $100 direct to the end user with do-it-yourself instructions.

People who pay $100 for the radios don't normally contract system
engineers to install them properly and when a professional engineer
endorses such radios by using them also, they are just cutting their own

throats.

Anyone who knows anything about radio should also know that dummies are
going to be putting all kinds of junk in these bands and there WILL be
uncontrollable, destructive interference at any time.

No matter how good your engineering skills are, it is just not a good
idea to use unlicensed radio for critical applications. That's as
shortsighted as using Nextel for public safety handsets.

IMHO you are wasting your talents and your customers money if you try to

design a reliable wireless system using unlicensed bands. No dish will
protect you from a roving RV with a 1 watt WiFi rig parking in front of
your dish. And you know there's not a thing you can do about it.

I cringe everytime I hear an IT person brag about how much money they
are saving by using 802.11 radios for important data links. They all
eventually appreciate the phrase; pay me now or pay me later.

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From: [email-masked]
Date: Thu, 29 Apr 2004 15:59:49 -0400

Jack,

I could not agree with you  more. I shook my head  when LAPD said they were
going to use Wi-Fi to send Mug shots to police officers in their car. I was
approached last year to spearhead an Engineering effort by a large defense
contractor (I have previously posted their idea here), they wanted to create a
nationwide 1st responders network based on unlicensed spectrum.

I meet with them several times and the more questions and issues I brought up
the more they said "That is why wee need you".  The project budget grew and
grew and grew, but no matter how many times I looked at it I said.....No-way.
.......
After working with Loral Defense Systems I knew defense-contractor speak, this
translated to "Fall-Guy".

The liability was just to great in using unprotected spectrum to protect US
citizens. Some said take the money and go with the flow, but I did not want to
be sitting in front of some 9/11 type Senate Committee years from now
explaining why I built a First Responders network based on spectrum used for
Baby Monitors.........

> From:  Jack Daniel <[email-masked]>

 
Yahoo! Groups Links

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From: Blake Bowers <[email-masked]>
Date: Thu, 29 Apr 2004 15:56:38 -0500

> nationwide 1st responders network based on unlicensed spectrum.

Just recieved the most recent copy of EF&P, Emergency Fire/Rescue and Police
product review magazine.  Inside, there was an article written by a Chris
Johnston,
of Radial Larsen recomending 802.11 license free equipment to public safety
and
municipal applications.

I wrote a message to [email-masked] and [email-masked]
suggesting
that they reconsider such a statement, that the lives of first responders
could depend on
it.

No reply as of yet....

 
Yahoo! Groups Links

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From: [email-masked]
Date: Thu, 29 Apr 2004 17:24:12 -0400

All these "Wiz-Bang-Plug-It-In-And-Go" solutions are going to get someone in
trouble.

Remember when the marketing gurus discovered the 900 MHz ISM band?

We had all of our Critical Infrastructure , Meter Readers, Arrogation Controls,
Substation management all running on unlicensed spectrum  Then the electronic
companies started making cordless phones, wireless video systems (remember the
Rabbit?), remote control toys all on the same band. Then the utilities
experienced numerous problems. Most moved to the protected  SCADA bands at
great expense. Look for a repeat of this. The wash post ran a story highlighting
the potential for interference on Wi-Fi. Maybe you should share it with him.

http://www.washingtonpost.com/wp-dyn/articles/A38700-2004Apr24.html

"Traffic jams are at the top of that list: When multiple WiFi access points,
hubs of individual wireless networks, sit  near each other, WiFi receivers can
see senseless noise instead of a clear data  stream. This is what happened at
the CeBIT computer trade show in Germany  last year, where a maze of overlapping
WiFi networks stopped many laptops from getting online."