• I currently have an issue with a site that I am working at and would like some feedback from everyone on how this should be handled.

    We have an 802.11g network in a warehouse that is having a lot of connectivity issues. After doing a Spec Analysis and an additional Site Survey I have found that another company next door has moved in and setup their own 802.11 network. This is where it gets hairy! From the middle of our warehouse I can see interference from 2.4ghz phones (from our neighbors) and as I move closer to them I can see multiple access points from them. On top of that they are using channels 3,5,7 & 9 for some ungodly reason. Common sense tells me they are causing all of my problems.

    However when I speak to our neighbors they had a "consultant" do the install and they don't manage it. On top of that they would not give me the conatct info of this "consultant" for me to contact them saying it was private info. So I left my contact info with them to forward along. I have since heard nothing.

    I see my only options as either 1) turning up the power on our AP's and blasting them, or 2) Getting a couple IDS sensors and start blocking their ap's (even though I think that is morally wrong since I would intentionally be doing it). If they will not respond to me do I have any other options?

    I am curious as to what everyone thinks about this? Sorry for halfway starting to rant about this!!

  • The number one source of interference for 802.11 networks is other 802.11 networks. If you and your neighbor can not reach an agreement as to channel use etc. you can not just use a WIPS to attack them, as that is not legal. They have every right to WiFi that you do. However, they also have the right to leave it as is so long as they are not doing so with the intent of disrupting other 802.11 devices. What you may need to do is change your PHY to the 5GHz range to avoid the interference. This is a common problem in multi tenant buildings and areas of WiFi congestion.

    Turning your power up may only serve to worsen the problem.

    Good Luck

  • Thanks Bryan for the reply. Yes, I understand on the legal aspects of the WIPS. Just wish I could :)

    If it wasn't such a chicken wire job I could understand but geez that jsut gets under my skin.

    Unfortunately I can't change to the 5Ghz range. All of our handhelds are 2.4Ghz. Which brings me to another question does Intermec actually make a handheld that has a 5Ghz radio?

    Thanks again!!

  • Oh, the every other channel approach. Tell me where you are located and I'll fly out and kick that "consultant" in the teeth. People like that are why some have a bad opinion of WiFi. </rant>

    Ok, how to solve your problem. What kind of building are they in? With you in a warehouse (I'm guessing large) and you are seeing signal from them, they must be really really close or in another open building such as a warehouse.

    What is the power level of the interference you are receiving? I guess I'm having a hard time with you getting that much interference from another building. I'm not saying it isn't possible, but I would like to know more.

    It would be mandatory for me to talk to that consultant. You should let them know that you plan on installing an outdoor WiFi system for mobile devices and that you will have to boost the power to just within legal limits. You of course don't want to cause them problems so you want to work together.

    If they call your bluff, I'll send you three AP's and antennas tuned for 3.99 Watts on channels 1, 6 and 11. That will get their attention. Completely legally since I know you want to surf the Internet from the parking lot... right? :)

  • I'd like to offer the following possibilities, if only to find out from someone who has tried them why they won't work.

    Avoid the interference
    I don't know about Intermec, but I think the Symbol MC9090G is a wireless bar code scanner that has an 802.11a/b/g radio.

    Block the interference
    There are paints and coatings that have substantial absorption at 2.5 GHz. I haven't priced them to see if it might be feasible to coat a large wall. Also, some people use foil-backed sheet insulation in buildings, including warehouses, that offers substantial attenuation for the inside of the building. This is affected by large overhead doors, but for your case it might work.

    Reduce the interference
    Using inward facing directional AP antennas that provide a pretty good F/B ratio might reduce interference enough help. One drawback is needing more antennas/APs to cover the same area adequately. If you have a drawing of your warehouse with AP and antenna placement, I could do a rough-cut prediction with LANPlanner just to compare the current pattern with a directional antenna solution.

    Cooperate with the interference
    If these neighboring signals are really strong, the level may be high enough to trigger your AP/client CCA, forcing channel sharing for both networks. If capacity isn't a big issue in your operation, your network might be usable on the same channels as theirs, using Channels 3 and 9. That's if by luck their channels 5 and 7 aren't the strongest signals in your area, creating lots of adjacent channel interference, which may be your primary difficulty right now.

    Charles Preston

  • If the primary problem created by the neighboring network is at your APs because of their better location and antennas, there are some narrow bandpass filters available for channels 1, 6, and 11 that might cut severe adjacent channel interference enough to salvage the situation.

    Charles Preston

  • Guys thanks for all the feedback. I appreciate all the ideas.

    GTHill, if I find them I will probably kick them in the teeth, but thanks for the offer!! :D

    Yes, we are in a large Distribution Center that is about 400,000 square feet and full of metal products. This neighbor is next door to us, physically attached to our building. It is also a wide open warehouse. I don't have my docs with me right now to tell you the power level of interference. I'll stop by my office and grab them this weekend though.

    I agree on talking to the consultant. Honestly, we do want to get along with the neighbors, etc. I am traveling back down there week after next to try and talk with them all again. Can't we all just get along. I am a decent poker play so maybe I can get a good bluff. Hey I can work from the parking lot anyday!!

    cpreston, we did an eval on the Symbol MC9060 model I beleive about a year or so ago. At that time I don't remember them having a/b/g radios. I could be wrong though. We decided to go with Intermec for a few different reasons.

    You also bring up a good point on the paint, and foil. I thought of something like that but I don't have any experience with it. Has anyone actually tried these methods before and would share the results?? As anywhere else the almighty $ rules to a point. Even though we need our network working better management still harps on keeping cost down. Go figure.

  • Boomer,

    fyi Intermec has 802.11a radios. CK60 Mobile Computer is just one. If you are still looking shoot me a note and I can get you some additional specs.

    We sell alot of Symbol and the 9090 has the a/b/g radio. Original 9060s only had the b/g.

    good luck.


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