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Wireless Network Interference

Posted on 2003-11-26
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Last Modified: 2013-11-12
Very small wireless network in a retail space using Netgear FM114P and Netgear MA101 adaptors. There is interference casuing the wireless network connection between the adaptors and router to drop.  Sometimes it will work fine for days, other times it will fail hourly (but works more often than not).  Unfortunately the store is using a 2.4 GHz telephone (Panasonic) and there are two wireless LANs that can be seen in the vicinity.  Workstations running XP Pro SP1.

Per Netgear, I have used the Netgear utility to configure  instead of the XP utility.  Have setTx rate to 5.5 and set to short preamble.  Using short WEP keys.  I have tried every channel, some work worse than others, but all exhibit problems.  I have repositioned the wireless router for oiptimal reception.  I have considered recommending that the telephone be replaced, but since they are using 2-line phone, 5.8 GHz models are out and 900MHz models are missing features they want.

First, am I missing any solution to make this current setup work?  There are no FCC approved boosters or antennas for these products.

Second, what are my alternatives?  
Copper is my last choice, the space does not lend itself to a retrofit.  It's doable if it's the only way, but expensive and "messy".  

I briefly considered 802.11a, but I'm concerned about distance (this is not a huge space, but it is my understanding that it can be as short as 50-100 feet, which would be a problem).

Now I'm considering PowerPlug adaptors (Netgear XE102).  However, Netgear does not "recommend" them in business environments.  Anyone have any experieinces with them?
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Question by:Quetzal
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PsiCop earned 250 total points
ID: 9824823
I also would stay away from the "PowerPlug" adapters. Industrial/commercial environment circuits tend to be very noisy, and even if it works you're unlikely to get decent bandwidth.

You're operating in a largely unregulated spectrum. If there's interference, then you sound like you've already taken every reasonable action to correct it. Its doubtful you can do much more.

If you suspect the phone, then you need to ask them which they want more - a working LAN or certain phone features. That will drive your decision on how to continue.

If they are willing to give up the phone features to switch to 900 MHz, then the problem may be solved. If it still isn't solved, they can always switch back to 2.4 GHz, can't they?

If they regard the phone as more important that the working LAN, I'd suggest falling back to your last resort and running a hardline, as its obvious the environment is too noisy, RF-wise, for a WLAN.
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by:chicagoan
ID: 9824919
That AP might not support higain antennas, but if it doesn't work you're either going to have to replace it with one that does, use multiple APs, hardwire or as a last resort phone line networking.
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by:Quetzal
ID: 9826640
WRT higain antennas..it is my understanding that if the problem is due to RF interference (esp  telephones that use DSS or FSS) such antennas aren't going to do much good.  Is that right?

HPNA would have been a great idea exept that phone lines aren't available in the right locations (and the runs would be just as long as for enet).\\

If I were absolutely certain that the telephones were the problem, I would jump on that with both feet.  However, I did a little testing over a short time with the telephones turned off.  I may have seen a 10-20% improvement in signal strength and link quality, but then again it could have been something else....it was not definitive.
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by:Quetzal
ID: 9826645
Is there an inexpensive way to determine the source of the RF interference?
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by:Quetzal
ID: 9826658
PsiCop, when you say I'm unlike to get decent bandwidth from PowerPlug, do you mean less than 1 Mbps?  I only need Internet browsing speed.
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by:PsiCop
ID: 9826989
I think  **effective**  PowerPlug bandwidth in a commercial environment is prolly measured in Kbps, not Mbps.
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by:chicagoan
chicagoan earned 200 total points
ID: 9827019
http://www.wavelink.com/
for how the pros do it

>such antennas aren't going to do much good
If the source is next to the computer, no it the AP's antenna is between the source and the computer yes.


>If I were absolutely certain that the telephones were the problem
You're going to have to do more observation - I'll bet they aren't helping but short of taking one off hook and observing a signal drop, you'll need more sophisticated equipment to do a proper site survey.






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by:koquito
koquito earned 50 total points
ID: 9833163
Did you try changing the channel ?
On your transmitter or router change the channel to a different number.
If still the same problem persists , you imight have to consider to change the location of your transmitter away from interfering devices, like wireless phones working at the same frequency, microwaves, etc. That is why its recommended to make a site survey before placing things.
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by:chicagoan
ID: 9841136
or just dump another AP out on the floor, something like an smc 2655 with POE is very simple to deploy.
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by:Bing CISM / CISSP
ID: 9862860
listening...
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by:Quetzal
ID: 9874528
I'm going to run copper, it's the only way to really solve this particular problem.
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by:chicagoan
ID: 9874708
Sometimes the answer is "You can't get there from here" :)
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by:PsiCop
ID: 9874737
Quetzal,

Glad we were able to help you with the solution. One of the best uses for EE is just this sort of "sanity check" and help to make sure that you're not overlooking a possible solution.
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by:Quetzal
ID: 9874861
You're both right.  I'm glad not to waste any time with PowerPlug.  Your answers made me look hard at how I will retrofit copper into this setting and it will be fairly easy, inexpensive, and look good; moreover, it will work.

In this case, the sanity check was very worthwhile.
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