Jeff Liebermann wrote:


I beg to differ. Unless I missed something in my post-midnight scan
of the specs, the wireless router's TX power is set and forget. If it
receives an extremely strong signal level report in the 802.11
management packet, the power remains the same. The ability to do
power control is there (because each device reports its RX signal
strength and SNR) but very few access points even try.


You are speaking of the specs on the USB card, I am speaking access
point ... and actually, I have never searched for power-throttling in
the USB card, I simply would not use it ... when the wife and I go out
and I search for APs, I want every possible mw in action, at a clients,
hotel, hospital, etc.

Having one side of transmission link error free is MUCH superior to have
both sides error prone!

I beg to differ. You're creating un-necessary interference. Let's
play with the numbers.


Let's not, I said what I meant, and meant what I said, one side error
free is better than two sides error prone.

The commodity wireless router belches about +12dBm. Yours is
allegedly +27dBm. Range doubles for every 6dB increase in TX power.
Therefore, your TX range is:
(27 - 12) / 6 = 7.5
time more than would be with a commodity wireless router. In terms of
coverage area, that's:
7.5^2 = 56.3
times the area. Assuming a uniform density of WLAN users in your
vicinity, you're trashing 56.3 times as many users or systems as
necessary.


No problem. I don't live in a dorm, trailer park, high-rise or
apartment building ... the software will automatically adjust to find
the best chan and recheck this decision, from time-to-time. If others
don't have that capability, they may wish to upgrade ... like I have
strongly implied, already, "If your AP is crap, toss it out!" I can't
imagine anyone here who failed to read specs before purchasing, however ???

You're also partly wrong about asymmetrical systems being superior.
The transition between a fairly good BER or PER (packet error rate) is
rather abrupt. What happens is that the AP simply slows down the data
rate until the PER improves. Since the connection speed can be
different in each direction, you'll get very good speed in one
direction, and probably very slow speed in the other. In addition,
things go insane above 54Mbits/sec connection speed. You might have
enough signal to go faster than 54Mbits/sec in one direction, but if
it's lacking in the other direction, the AP will simply revert to
802.11g and limit the speed in the stronger direction to 54Mbits/sec.
That's not a problem as few systems can operate reliably at
54Mbits/sec beyond a few meters range and in the presence of
interference.


The equip can do b/g/n (b&g for the usb card in question, multiple
computers here) With a windows widget to monitor my ap/card connection
(transfer rate, errors, signal strength, etc.), I see it rise and fall
from time to time. Sometimes I have seen the connection renegotiate
from n to g to b ... however, at this same time AirSnare has went nuts.
Seems wardriving teens are to blame ... grin I was a teen once, so
long ago, I fear I may forget ... :-(

But, I will tell you, if ever I notice a problem with the errors (just
looked, 3 errors), I will remember your words.

Meanwhile, you're operating an alligator, jamming 56 times as many
users as necessary, and polluting the airwaves with your overpowered
xmitter. It's like operating a kilowatt xmitter in the middle of the
QRP frequencies. Your stuff gets through, but nobody else's. I
suggest you do the math, repent your evil ways, offer sacrifice to the
radio gods on the hibachi, slap yourself on the wrist several times
for penitence, and stop playing with the dark side.


Although, I am sure one or two of my neighbors are savvy enough to set
their routers into non-broadcast mode of the SSID, and have WPA and
filter on mac addresses, I just don't see the traffic/jam you speak of.
But, like I say, if I do, I shall remember your words.

However, although I have a pocketfull of various USB dongles, my
external USB wifi "card" is the highest output I could find which is
cost effective (@ 500mw.) External USB being powered off the USB buss
must stay 500ma (@ 5v) or below, total consumption. And, would more
than allow for a 1 watt USB dongle.

You would do better with a directional antenna, so as to not both
pickup and deliver interference from other systems. Antennas with
gain also improve the system gain in both directions, thus preventing
the creation of an alligator.


No, I would NOT. When I take my laptop and USB antenna analyzer out to
the antenna(s), I appreciate my omni. When I take my laptop and USB ODB
II out to the car (in another direction), I appreciate my omni. When
teens go by wardriving and trigger AirSnare warnings (and giving me
one-hell-of-a-kick!), I appreciate my omni. You hang around with the
old men here, beware the cynicism, it IS contagious!

Here is a USB card to match my router:
http://www.data-alliance.net/servlet...802.11n/Detail

Try one, you'll like it, "Mikey does!" grin

Nope. Instead, I was instrumental in convincing at least one mesh
wi-fi vendor to reduce their poletop TX power, as they were causing
most of their own interference. Asymmetric systems suck.


Beware. Again you risk being controlled by the control freaks here.
Glad it works for you, attempt to enforce it for me, we have a battle
.... you know, there is equip and hacks available to open up chans far in
excess of what is legal, I am sure some are savvy and use them ...
perhaps teenagers? straight face I have even heard of some flashing
their ap/cards with the foreign version of the software for them and
exceeding power/chans ... shame on them! :-|

Regards,
JS

Bah-Humbug (T'is the season).


However, you provide good discussion, and have valid arguments, I am
sure--some will agree with and appreciate--perhaps even some which are
state-of-the-art!

Personally, I would NEVER suggest purchasing an AP/card with less than
350mw capability. And, only then if you get one-hell-of-a-buy.

Warm regards,
JS

John Smith wrote:

...
Personally, I would NEVER suggest purchasing an AP/card with less than
350mw capability. And, only then if you get one-hell-of-a-buy.

Warm regards,
JS


Sorry to have been so verbal. I could have summed that up rather
quickly, nicely and sweetly, I choose not to ...

You see millions of cell phones; You see a LOT of problems?

Regards,
JS

On Mon, 08 Dec 2008 11:35:12 -0800, John Smith
wrote:

You see millions of cell phones; You see a LOT of problems?

Oh yes, I certainly do see problems. They're well hidden and
mitigated in various ways. For example, if the error rate climbs, the
adaptive tx power control cranks up the power on both the handset and
the cell site end. If it persists, you get disconnected. Rather than
have the user sound like they're talking while gargling ball bearings,
the cell site just pulls the plug. Incidentally, the tx power control
algorithm is rather messy as it has to handle different data types, at
different rates, all while doing its best not to drain the handset
battery. One the cell site end, it's no better as the power
consumption of a typical cell site is non-trivial.

Problems? Well:
http://www.roughlydrafted.com/2008/08/28/the-inside-deets-on-iphone-202-and-dropped-calls/
Hmmm... power control algorithm again.

Todays typical cell phones run about 150mw max average power output
(according to the FCC ID data). Some are even less. None are
anywhere near the 600mw legal maximum. If they could, you would have
a dead battery within about an hour. (Do the math).

Back to wi-fi and your setup. Sure, you'll have fairly good
preformance with a high power setup. 14 times the usual power is
bound to do some good. However, I suspect your neighbors are not so
thrilled and will probably also be shopping for higher power hardware.
It will be like an arms race, where the biggest bomb allegedly wins.
Dealing with mutual interference is no fun, especially with only 3
available non-overlapping channels.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
On Mon, 08 Dec 2008 11:35:12 -0800, John Smith
wrote:

You see millions of cell phones; You see a LOT of problems?

Oh yes, I certainly do see problems. They're well hidden and
mitigated in various ways. For example, if the error rate climbs, the
adaptive tx power control cranks up the power on both the handset and
the cell site end. If it persists, you get disconnected. Rather than
have the user sound like they're talking while gargling ball bearings,
the cell site just pulls the plug. Incidentally, the tx power control
algorithm is rather messy as it has to handle different data types, at
different rates, all while doing its best not to drain the handset
battery. One the cell site end, it's no better as the power
consumption of a typical cell site is non-trivial.


Yes, hackers (well, you may prefer programmers/software-engineers?) do a
very nice job, they have done it with wifi too, still doing it actually,
personally--I suspect viagra! LOL

Problems? Well:
http://www.roughlydrafted.com/2008/08/28/the-inside-deets-on-iphone-202-and-dropped-calls/
Hmmm... power control algorithm again.

Todays typical cell phones run about 150mw max average power output
(according to the FCC ID data). Some are even less. None are
anywhere near the 600mw legal maximum. If they could, you would have
a dead battery within about an hour. (Do the math).


Yeah, personally, I could handle a cell phone 2x to 3x the size, most of
it battery ... my cellphone is 300mw out (max, but variable, as needed,
as you state), I read those specs before purchasing, also. 4 hours max
talk time (like if your sitting right under the tower?) is no problem
for me, mine averages 2-3hrs, but I have a pocket charger, takes two AA
high output recharge-ables (you can chuck alkaline in if needed) and is
quick, chat while charging, so never without power (did I mention 2 week
standby time?), now ask the wife, you get another answer ...

Back to wi-fi and your setup. Sure, you'll have fairly good
preformance with a high power setup. 14 times the usual power is
bound to do some good. However, I suspect your neighbors are not so
thrilled and will probably also be shopping for higher power hardware.
It will be like an arms race, where the biggest bomb allegedly wins.
Dealing with mutual interference is no fun, especially with only 3
available non-overlapping channels.


My son and I, once or twice a year, attend a game fest. There is more
high power equip set up than you can shake a whatever at ... doom,
heretic, diablo, etc. (you can tell, I like the old ones :-( ) nets all
off separate APs, the wifi cards are simply uncountable--if you think
thats nuts, attend a gaming convention in Nevada, frankly, I would have
to state, from REAL hands-on, the problems you state just don't exist to
a REAL degree ... if they/it did, they would be fixing that now (more
chans, tighter packet packing/encryption, more-adaptable, spread
spectrum, etc. Remember, networking has NOT EVEN reached its' infancy,
yet!) Without a doubt, there are conflicts and lost packets--you just
never notice them--now, if everyone there started, separately, watching
a HD movie, most-likely no joy ... :-(

Besides, my neighbors are idiots (technical idiots, I admit, I like a
couple of 'em), I doubt they do anything but email/surf and download an
illegal movie/song now-and-then -- well, I suspect them of porn--but I
am like that yanno? Suspicious.

But hey, if everyone agreed with me, I would NOT be here, and this would
NOT be fun--did I mention it would be boring? wink

Warm regards,
JS