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Thread: Bachelor Towers Apartments

  1. #1

    Default Bachelor Towers Apartments

    Hi All,

    I've been asked to look into some issues in a serviced apartment building. There are about 90 small apartments which are mainly used by professionals. They are unoccupied during the day, and all the activity is between 6pm and midnight. They complain of drop-outs and issues using the wifi. We've installed an ADSL router with 802.11bg in each (single-chain 2.4GHz).

    I have been in today to check with chanalyser. It seems there are normal signatures for 2.4GHz wifi, but while there I noticed a problem with the microwaves. The builders installed this model of microwave (Siemens) in every apartment, so during the evenings there is potential for interference. It seems to be centered around channel 11, but the whole spectrum is affected to some degree.

    Attached is the recording. You can clearly see when the microwave is on. Any advice in this particular scenario? Would we benefit from 802.11n and/or dual-band APs?

    I am planning to go back in there in the evening and get another capture.

    as microwave.wsx


  2. #2


    Ouch. Yes it looks like your Microwave ovens are really borking your Wi-Fi. I don't think 8011n will offer much help in the 2.4GHz range (I stand to be corrected here) as it still operates in the same frequency. You would be better of switching to the 5GHz frequencies used in 802.11a. The problem with this of course is that all of your client devices must also support 802.11a (5GHz) if they are to use it.

  3. #3


    802.11a is obsolete. If moving to the 5GHz band, use 802.11n or the just emerging 802.11ac technology.
    Old Mod by the Sea

  4. #4


    Channel 1 looks a little cleaner, but every AP on channel will spell problems too

  5. #5


    It is better to have other AP's on the same channel rather than an adjacent or overlapping channel. At least when multiple AP's are on the same channel, they are aware and understand each others signals. If they are on an adjacent or overlapping channel, their signals are perceived as "noise".
    Old Mod by the Sea

  6. #6


    yeah of course. What I should of said was 802.11n 5GHz. But still the problem would be the same. The clients need to support the 5GHz band.

    My brand new Lenovo laptop is 802.11n however it only has 2.4GHz radio, so there are plenty out there that may not be supported if they were to switch to 5GHz 11n or indeed 11ac.

  7. #7


    survey constantly to identify apartments or zones where are more or less use of microwave oven

    looks like the most affected channel by microwaves is channel 11, and is too the channel most active at least in the time of capture.

    Looks like there are some APs on channel 3.

    its a hard situation, that can be mitigated but not completely, taking some actions maybe help:

    relocate wifi ap far from microwave oven and closer to location of wifi client in each apartment

    design a rf planing scheme where you locate some ap on channel 1 an others on channel 5 trying to minimize channel overlapping using channel 1 in zones of high microwave oven usage and channel 11 in zones of low microwave oven usage

    lower the APs data rate to 36m or 24m 802.11g data rate to improve stability, of course at some cost in throughput

  8. Default

    Yikes, that interference is pretty rough. Some good ideas so far!

    Here are my recommended actions:

    1. Get dual-band 802.11n (2.4 and 5 GHz) access points. The 5 GHz capable clients will enjoy increased reliability, and single-band clients will use the less reliable band.

    2. I see a few signatures on non-standard channels, such as channel 3. That's going to hurt the network on channel 3, and networks on channels 1 and 6. Use non-overlapping channels 1, 6, and 11 only. Remember, it's ALWAYS better to share than it is to partially overlap.

    2. Building on that, and because of the interference, move all AP's away from channel 11. Instead, place them all on channels 1 and 6. Unfortunately, that's going to make for a very dense environment, but managing spectrum is all about finding balances. Offloading as many clients as possible to 5 GHz should help that issue a bit.


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