wireless signal changes???

Discussion in 'Tomato Firmware' started by philtrim, Dec 4, 2009.

  1. philtrim

    philtrim Addicted to LI Member

    Over the last few days, my wireless signal has been falling from excellent, to below average for no apparent reason. Nothing has been moved, no new obstructions, or devices. I normally kept a excellent signal until this week. Router is in the same place, antennas have not been moved. No settings have changed on my laptop's NIC card or the Tomato settings. Knock on wood, I am currently running/connected with an excellent signal, but that could change later.

    Any other things to look for that could be interferring or causing my signal to degrade?


    Linksys 54gl, Tomato ver 1.23
  2. TexasFlood

    TexasFlood Network Guru Member

    Below are some results from a quick google search.

    This may or may not be related but I personally have had chronic trouble with microwave interference just "nuking" (pun intended) the wireless in my home. I recently read that microwave interference is towards the upper part of the 2.4HHz spectrum. I tested coverage years ago and found at the time channel 9 gave me the best coverage so set my routers that way and have never changed it since it seemed to work. After reading the article about microwaves, I switched to the lowest available channel, channel 1, and sure enough I microwaved a big bowl of water and didn't lose wireless for the first time in years. So it's still possible to learn and adapt, :grin:

    From Wikipedias "IEEE 802.11g-2003":

    Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include: microwave ovens, Bluetooth devices, baby monitors and, in the United States, digital cordless telephones, which can lead to interference issues. Additionally, the success of the standard has caused usage/density problems related to crowding in urban areas. To prevent interference, there are only three non-overlapping usable channels in the U.S. and other countries with similar regulations (channels 1, 6, 11, with 25 MHz separation), and four in Europe (channels 1, 5, 9, 13, with only 20 MHz separation). Even with such separation, some interference due to side lobes exists, though it is considerably weaker.

    From Wikipedias "IEEE 802.11":

    802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States under Part 15 of the US Federal Communications Commission Rules and Regulations. Because of this choice of frequency band, 802.11b and g equipment may occasionally suffer interference from microwave ovens, cordless telephones and Bluetooth devices. Both 802.11 and Bluetooth control their interference and susceptibility to interference by using spread spectrum modulation. Bluetooth uses a frequency hopping spread spectrum signaling method (FHSS), while 802.11b and 802.11g use the direct sequence spread spectrum signaling (DSSS) and orthogonal frequency division multiplexing (OFDM) methods, respectively. 802.11a uses the 5 GHz U-NII band, which, for much of the world, offers at least 19 non-overlapping channels rather than the 3 offered in the 2.4 GHz ISM frequency band.[2] Better or worse performance with higher or lower frequencies (channels) may be realized, depending on the environment.

    Also check out:
    Wi-Fi Planets "Be Wary Of Potential FHSS Interference" and
    InformITs "Comparing 802.11a, b, and g: Channels and Interference".
  3. Toastman

    Toastman Super Moderator Staff Member Member

    Texasflood's post is probably the most likely explanation.

    There is another - take a look at this post. But most probably I think you would see some evidence of another router, though one of the locals told me he gets interference from his N router on a WRT54GL that doesn't show up in the device list.

  4. TexasFlood

    TexasFlood Network Guru Member

    You're quite right, didn't occur to me but I've heard the same. In fact, thinking this -could- happen to my neightbors if and when my RT-N16 arrives. I've read that some wireless adapter manufacturers, such as Intel, don't allow their hardware to use 40MHz channels on the 2.4GHz band to be 'friendly' to neighbors.
  5. Planiwa

    Planiwa Network Guru Member

    Observations, measurements, patterns, perspectives, time series logging, time-correlates ...

    A problem solver would look forward to the next event, rather than knocking on wood. :)

    Then he would note the time, and look for associated changes or patterns.

    What exactly "degrades"? Is it the signal as measured by the router? The signal as measuerd by the PC host?

    Does it affect anything? Latency, packet loss, throughput, arping latency, ...

    What is the local environment like? Apartment? House in dense neighbourhood, sparsely packed neighbourhood, ...

    Ideally, one would look for measurables, and set off alarms when there is a significant change in signal quality, or whatever.

    There are two opposite complementary approaches to problem solving:

    [1] Try this and that and that and that ...

    [2] Observe. Find patterns. Experiment. Monitor. Diagnose. Study. Learn. ...
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