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Why do I keep experiencing frequent dropout from a wireless 802.11b network?

Posted on 2003-10-26
Medium Priority
Last Modified: 2013-11-09
I am using a Dell Inspiron 5150 laptop running XP pro, with a Sitecom 802.11b compatibal wireless LAN PCMCIA card. I am located 15 metres from the Cisco Aironet 350 series AP. Upon conection my signal strength ranges from good to very good, and ocasionaly low,  never very low though. I am also able to use the full 11Mbps while connected.  Anoyingly the connection drops out regularly every 5 mins or so. I get the dialoge box saying 'one or more networks are available' and have to manually reconnect.
I would apreciate any help!
Question by:chrisloxton
  • 3

Expert Comment

ID: 9625972
Hi chrisloxton,

You're not going to like this, but RF is a real pain in the butt. It can be extremely unpredictable. I work for a company that designs wireless security systems, and we run a wireless 802.11b network from our building down the road because ADSL is not supported at our building but is down the road. Okay that's a side comment.

Now, here are things that could affect your wireless network:
 - Interfearence from other wireless devices communicating on the same frequency / channel. don't doubt it until you check. Hell the building next door could kill it if they had a strong enough transmitter. Remember that these run on the 3.2gHz "range".

 - Interfearence from people walking in between. Most of the 802.11b stuff I've seen and used operates on the 3.2gHz frequency and it just so happens that your body (and trees as well) resonate at the same frequency. In short, that means that people walking in and out of the line of site can kill it to a degree.

 - Poor equipment. I can only recommend DLINK equipment. I've used it a lot and have had no problems with it. Check other recommendations and reviews online.

 - The orientation of the laptop. If you move it around another way, it can cause problems with range and signal strength.

 - If it is a laptop and you run low on power that can play games with your wireless card.

 - The framework in your walls, if aluminium, could cause problems.

That all being said, I think the key is the message, 'one or more networks are available'. It could be that somebody else is running another AP so the laptop is just giving you the choice.

It could also be your AP is transmitting multiple network IDs if it is faulty, but again this would be more of what we call at work, "the bullshit factor".

It could also be reflection, but this is much much less likely. I haven't seen it, but would hardly be suprised given some of the crazyness I have encountered with wireless. Again, the bullshit factor.

I think however the most likely is that there is another AP within range, and your card is just detecting it. If you signal strength goes south, then perhaps they're on the same channel. I would recommend using a different channel first, then if that doesn't work, I would move closer to the AP, preferably right next to it, and see if the same thing happens. If that happens, try and borrow someone else's AP and see if that causes the same crazyness.

Honestly mate, this is going to be be one of those things where you just have to eliminate the various factors. I will also give you a piece of advice in that if you do end up moving closer to the AP and it doesn't correct the problem, don't move back to your original place and continue troubleshooting as it may only compound the original problem. Find it in the best possible environment and then start to test the boundaries.

I hope this helps. :-)


Expert Comment

ID: 9625981
Also, it's not 3.2gHz it's 3.2GHz. Case matters. :-)

Author Comment

ID: 9626695
Thanks for the reply flanque.

The strange thing is, I live in a complex of flats which  has 5 AP's 'strategically' positioned to allow the signal to reach all residents rooms. I am situated on the top (5th) floor and, as mentioned, about 15m from the nearest AP, maybe 50m from the next closest. A friend of mine on the ground floor is located further away from his nearest AP but maintains an 'excellent' connection pretty much all the time, with very rare dropouts.
This lead me to believe that its is possibly my wireless LAN PCMCIA card?? - although the fact that it connects atall in the first place would probably counter this.

I will try locating my laptop right next to the AP and see how long the conection remains for.

Thanks once again

Accepted Solution

ViTaMiN earned 200 total points
ID: 9627594
I had this once on a network I disabled the option to work offline in the windows explorer tools\folderoptions\offline files and clear the checkbox before enable offline files.

you can also check if your os can shutdown your wireless nic for power savings.

to rule out a ap failure just sit next to your friend on the first floor and see if it still happens. so you know where to look.

good luck

Expert Comment

ID: 9632436
Hi chrisloxton,

No problems with the advice. I don't mind helping since this place helps me from time to time. Just a pointer, it doesn't necessarily mean squat that your friend can connect when he's further away. Remember, the overall 'environment' that he is in, is totally different to that you're in. Different surroundings, materials, bodies, etc.

I would take ViTaMiN's advice and sit next to your friend's and then try to connect. Next I would be trying a different PCMCIA card - one that you know works. :-)

Let me know.

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