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Most notebook WiFi cards can download at 1.8Mbps max, but some can download at 6Mbps

Posted on 2007-08-12
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Gentlemen,

I really need help understanding why notebook wifi cards are having a practical bandwidth cap of 1.8Mbps, even though the negotiate line speed is 54Mbps, and the line to the internet provides a fairly reliable 6Mbps actual bandwidth for my notebook computer.

I've posted this question in another question area, but I'd really like to get more thoughts from more minds on this.

Here's a link to the original question.  It contains information that I've learned so far.
http://www.experts-exchange.com/Hardware/Networking_Hardware/Wireless/Q_22684085.html

Thank you very much for your help!

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Question by:ChrisEddy
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by:Rob Williams
ID: 19680179
54mbps is the maximum theoretical speed you can expect to get over your local network. PC to PC in house.
No Internet connection will work at that speed. The limitation when downloading from the Internet is your ISP's advertised connection speed which I assume is the 6mbps. To add to that, that is the maximum theoretical speed you could get directly from your ISP assuming there are no other factors such as other users, if cable even other users in your neighborhood. That doesn't take into consideration what the upload speed is from the site from which you are downloading. Your speed is dependent on the weakest link in that speed. Having said that 1.8mbps is actually very good.
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by:ChrisEddy
ID: 19680447
Thank you for your kind response.  But I know this.  

My question is: why is the bandwidth delivered via this notebook wifi card, measured at 1.8Mbps, which was not limited by the connection speed between it and the wifi router - which was negotiated to be 54Mbps, and was not limited by the speed of the line to the internet - which is rated at 7Mbps  Because my notebook computer, which was sitting right next to this one, was connected to the exact same Wifi router, and was getting about 6Mbps.

Other than a distance of about 2 inches between the two notebook computers, I am still at a loss for why one wifi card has a practical bandwidth maximum of about 1.8Mbps and another can communicate at a much higher rate.

I've talked with a dell tech support person, and he had also recently discovered this 1.8Mbps cap in the maximum bandwidth of some wifi cards.  His solution was to replace the card, which I have done on another computer and it did break through the 1.8Mbps cap on the bandwidth delivered through the wifi card.  

I hope to learn why this 1.8Mbps exists with some notebook wifi cards, and what can be done to solve this problem without replacing the apparently slow hardware that is the wifi card.


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by:Rob Williams
ID: 19680460
Sorry, seems I misunderstood.
What make are the cars. May be same reason I buy $70 Ethernet cards when you can buy others fr $7. Some perform better than others.
I assume they are not the same card in the 2 machines.
I see it has been suggested already in the other thread to update the drivers.
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by:Rob Williams
ID: 19680846
Doing some reading 1.8 seems to be a common cap for different wireless devices, but as you say no reason for it to limit your connection. Sorry no help.

You really should close one or the other question where they are covering the same topic, as per EE guidelines.
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by:Jeff Brown
ID: 19684298
Check  your power management settings.  This is a common way in which "centrino" laptops save power.  i know i know  you even had it plugged into the wall and saw the same result.  but the change over for centrino is very wonky so i would not  count that as a valid test.  cut centrino power management totally off  both in the bios and inside windows and run your speed tests again.
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by:Lebnitz
ID: 19694425
There're several reasons:

1.Range, weather conditions that affect wireless speed.

2.Quality of the Access Point. Yes, some cheap AP can not handle huge volume of data. Even you've tested that you can get decent wired speed with the AP, wireless speed is totally different. These low-end integrated DSL router-wireless access point are just build for functionality, not quality.

3.Configuration of the AP. If you set up your AP with security check: WEP, WPA, MAC filter,...your speed will degrade significantly.

With my old trusty Cisco 340 AP, Linksys WPC54G wireless card, no WEP or WPA, signal 62%, strength 74%,11 Mbps thereotical; i can get true ~4 Mbps .

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by:cpmckenzie
ID: 20792560
Well I agree. I have a new Sony SZ with an Intel 3945ABG. It is connected to an access point and shows 54MBps but can only download files from the network at 1.8MBps. For example when we use the ethernet cable (100Mbps) then a 250 MB file copy takesd about 35 seconds. When we copy the same file using the wireless it takes 14 minutes...

Older laptops do not have this issue.

I am wondering if somehow the 1.8 limit is linked to the "mobile connectivity" ripofff included in the Sony. I have also reinstalled the machine from scratch as like the author I am struggling to comprehend the point of claiming 54MBp[s when only 1.8MBps can actually be achieved. What a crock as usual.

However, some bright spark amongst you might know the answer to this. Obviously buying another card after spending £1,700 on a PC is an interesting option...

Best as always
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cpmckenzie earned 2000 total points
ID: 20806872
Chris
I have spent all of Saturday on this! The plain fact is that "out of the box" the new laptops Sony SZ Series with the Intel 3945ABG card simply will not download files faster than 1.8Mbps in spite of showing 5 bars and a G connection.

My actions were as follows:
I upgraded the driver to the latest 11.5.032 driver. Dell have one and Intel have one but it is listed under the 4965agn. http://downloadcenter.intel.com/Filter_Results.aspx?strOSs=All&strTypes=all&ProductID=2753&OSFullName=All%20Operating%20Systems&lang=eng

I then fiddled about with the power management. Taook off the default. Put it to halfway. Rebooted. Put it to full. Rebooted. (no effect).

I then turned off the bluetooth - on the Sony this is done in "Wireless Switch Settings" - Big result. 278Mb in 4 mins.

I then turned on the bluetooth again and rebooted... 27 mins.

Now I am not saying this is the answer.. as 278MB in 4 mins is still only about 11MBps.. but it is better than before.

I changed the settings on an IBM.. speed increased.
I changed the settigns on a Dell. - speed increased

Hope this helps

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by:ChrisEddy
ID: 20808534
Interesting finding, that the presence of Bluetooth slows down your wifi speed.

I still have access to one of the notebooks that originally motivated this question, and can test your suggestion.

Note that I have a 4.5 year old Dell Inspiron 8600 with an Intel 2100 card and what the Device Manager is reporting as a "Bluetooth LAN Access Server Driver", and the fastest internet access I have tested over a 7mbps DSL line is about 6mbps.  

The i8600  has a separate Bluetooth card that slides into the side of the left front.  The disk drive is taken out, a small connector for the twisted pair wires from  the Bluetooth card are attached to a nearby motherboard connection, and the thin and long card can be slid in to interior of the notebook case.

Since posting this question, I've found this wifi performance reduction in several more notebooks.
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by:cpmckenzie
ID: 20813637
Hi Chris
Thanks to you I have been spending a lot of my time testing notebooks too!! The common factor is the 3945ABG chipset but the solutions on three I tried on Sunday afternoon were not consistent. However they were all speeded up!

My prognosis was that the speed is showing 1 or 2 mbps in the first place. By changing the settings and flicking them on and off etc I can enabel the speed to 54 mbps. My optimium settings for the card are:

ad hoc channel 11 (or the channel you are using mostly).
adhoc power management-disabled
adhoc QoS-WMM disabled - (This one really makes a difference)
mixed mode-cts to self enabled
roaming aggressiveness-3 medium (Put it higher and you slow down...)
throughput enhancement-disabled - (Crock of shit and does not work)
transmit power-5 highest
Wireless mode #6 all 3 a,b,and g (Ths was really to give it a kick in the bottom).

However the network utilisation is still very low on big file transfers. 10% or less. I went down a lot of blind alleys with registry settings and so forth. Waste of time.

My rather basic calculation is as follows:

Wireless Coonection speed x (Network utilisation - Collsions) % = Throughput
54 x (10-3)% = 3.78 mbps for example.

But I was only really achieving 1.5 MBps (270MB in 240 seconds).

Just for fun google search "Intel 3945abg Crap" and you will lget a lot of results

So after all this I am confirmed in my belief that Intel have capped the throughput at 1.5 mbps whatever you do!! I think the problem is the way the 3945 chipset allocates resources on the motherboard and a discreet card, rather than an instegrated one simply works better.

I have bought a Netgear card and it works.... 25% Utilisation 54 Speed 1 minute download of 270MB...

Hope this helps you and confirms your suspicions. it has been an interesting reseach project.


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Expert Comment

by:cpmckenzie
ID: 20813664
NB: I missed the power management setting. This is the first one to try. Set it off defaut and move it to medium. reboot. Set it to highest. Reboot. (Apologies)..
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by:cpmckenzie
ID: 20813676
Of course if any bright spark does get the answer I will stand corrected and be very appreciative.
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