Why does the connection speed slow down?

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When I first start up the laptop, the wireless network connection tray
icon shows the speed as 54 Mbps.  After several minutes, it drops and
fluctuates between 1 and 18 Mbps, spending a lot of time at 1 and 2
Mbps.  Signal strength is always shown as "excellent" as the wireless
router is just across the room.

Is the tray icon tool accurate?  If so, why does the connection speed
slow down?


Re: Why does the connection speed slow down?

shepard97504@yahoo.com wrote:
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I can tell you my experience :  I had the same problem, and after a
couple of days of scratching my head, I discovered a school close to me
has a wireless lan broadcasting on the same channel 1

I suppose they have installed an outdoor antenna, to reach all the
rooms.  Altough I'm not able to spot it.

My suggestion is to change from the default channel(1) to another one.

Re: Why does the connection speed slow down?

On 15 Jul 2005 23:43:38 -0700, shepard97504@yahoo.com wrote:

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This is normal response to interference and reflections.  How much
speed juggling it does is dependent on the algorithm used.  The way it
works is that the client tries to associate with the access point at
the highest speed possible.  This is advertised in the management
frames so there's no trial and error involved like in dialup modems.
It usually succeeds making the initial connection at the highest speed
because there's very little traffic moving and the probability of a
successful association is rather high.

That usually remains the situation until you start moving data.  At
54Mbits/sec association speed, anything furthur than about 8ft range
(using typical antennas) is going to create data errors.  The data
arrives corrupted by noise.  The access point detect the arrival of
corrupted packets and lowers the speed in order to reduce the error
rate to reasonable level.  Depending on range, it will reduce the
speed until it gets a decent error rate (about 1 error in 10^5 bits).

However, that how it should work without any interference present.
With interference, there's a problem.  The speed can go down to the
very slowest speed (1Mbit/sec) and there will still be errors.  In
fact, since the same size packets take longer to transmit at the
slower speeds, the probability of a packet getting trashed by
interference is even higher with slower speeds.  Having the speed
plunge to 1Mbit/sec is a sure sign of local interference.

A good question is how does this system recover from an interference
hit?  In other words, what criteria or algorithm determines when it
should increase in speed again.  I had illusions that some
sophistocated statistical algorithm was employed.  Nope.  One AP
product used a simple timer.  After 10 seconds of no traffic, it would
reset the speed back to the maximum speed and just start over.  I
suspect most are like this.  Cheap, crude, functional, but not very
elegant or optimal.

Jeff Liebermann    jeffl@comix.santa-cruz.ca.us
150 Felker St #D   http://www.LearnByDestroying.com
Santa Cruz CA 95060    AE6KS  831-336-2558

Re: Why does the connection speed slow down?

Its a known problem with a Intel 2200BG wireless setup (bet it is) and is
waiting for Intel to publish a reasonable driver. Uninstall proset and use
the WZC setup with XP with Version 8 drivers (install only the card drivers)
and thing will get a lot better. Then scream loudly at who sold you the
laptop, who hopefully will scream at Intel. If you cant find V8's email me



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Re: Why does the connection speed slow down?

Wow, I read that thread and that is exactly my problem.  It is amazing
that it has been unfixed for so long.  I have a brand new HP DV4040us
with the 2200.  The drivers and fixes listed in that thread do not seem
to work for most people.  I guess I will just have to wait for Intel to
release drivers that do fix the problem.

Re: Why does the connection speed slow down?

On 17 Jul 2005 00:11:03 -0700, shepard97504@yahoo.com wrote:

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I just read through all 233 articles in that blog.  Methinks almost
everyone is ignoring a common issue.  The few that bothered to post
details on their hardware indicated that they were using Linksys
WRT54G access points.  Much of the rest is consists of trial an error
testing of various drivers with very inconsistent results.  Are you
prehaps using a Linksys router?

What everyone seemed to be ignoring is that it's the access point, and
not the Intel Centrino client, that sets the speed.  Centrino simply
follows the speed that the access point commands.  If the forum users
had tried to set the speed of the access point to some reasonable
speed (i.e. about 12 or 24Mbit/sec), instead of "auto", they would
probably have found that their connection was stable.  It would be an
interesting test.

My guess(tm) is that Intel's driver isn't returning some management
request in time for the access point to respond.  This is not the
first time this has happened with the Philips Centrino chipset.  When
the Netgear MR814v1 was new in early 2004, when the Centrino chipset
started to appear in OEM laptops, the two devices would connect and
drop repeatedly.  I never did find out exactly which company screwed
up, but Netgear was forced to loosen their timing specs to accomidate
Centrino.  (Biggest company always wins).  I'm guessing this is more
of the same.

I don't have a fix.  Try the various Intel drivers and see what
happens.  If that doesn't work, try setting the access point to a
fixed but reasonable speed and see if that helps.

Jeff Liebermann    jeffl@comix.santa-cruz.ca.us
150 Felker St #D   http://www.LearnByDestroying.com
Santa Cruz CA 95060    AE6KS  831-336-2558

Re: Why does the connection speed slow down?

No Linksys here. I have a D-Link, like some of the people in that blog,
(and in a couple of other forums I found), with the same problem.  Most
do have Linksys, but that may be because that is such a common brand.
I think there were a couple of other brands of routers also.  The
common thread was the Intel 2200 and the other Intel one.  I don't know
if there was anyone who posted there that had the problem fixed by
downloading drivers.  A few thought they had fixed it, only to find out
later it was not fixed.  The only ones who fixed the problem seemed to
have changed to something other than the 2200.  That seemed to fix it
in 100% of the cases, regardless of the brand of router.  I am hesitant
to start trying a bunch of different drivers as I am not a tech person
and it seems the likelihood of that fixing things is slim.

I guess I will just live with it for now and hope that a certain fix is
put out soon by Intel.  Amazing that it has persisted this long.  I
called a few acquaintances with this same wireless setup and they all
confirmed they had the same thing happening.  I try to use an ethernet
connection when downloading updates and programs so the wireless card
does not affect that.  Browsing sometimes slows to the point of
dropping the connection, but almost immediately reconnects at a higher

Jeff Liebermann wrote:
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