On Mon, 08 Dec 2008 01:51:53 -0800, John Smith
wrote:
Jeff Liebermann wrote:
...
Turn down the power to about 100mw. The antenna is fine because it
results in a symmetrical improvement in system gain. Also, give
yourself a slap on the wrist, repent your evil ways, and pray for
forgiveness.
Throw out your access point man! Get a decent one ...
You haven't seen my office. I never throw anything away.
Regards,
JS
Yes, my AP's software allows for power control. Indeed, the AP will,
automatically, only supply enough power to make a, almost, error free
transmission link.
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.
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.
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.
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.
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.
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.
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.
Regards,
JS
Bah-Humbug (T'is the season).
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558