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I am using 802.11g in my apartment block.

There must be many tens of WiFi networks that my laptop detects.

My issue here is that my transfer speed over my WiFi network is topped to 1 MB/s... O_O !!

I think this may be caused by the interference with so many other WiFis in the same area.

How can I troubleshoot this and maybe a solution would be to set my frequency to something else, but which one?

Also, my wifi mode on my router is set to "Mixed", because my laptop is G, and my girlfriend's is N. Should I buy a new wifi card on my laptop to be N compatible and then set my router's mode to "N" only?

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closed as off topic by RobM, Jacob, Wesley, Holocryptic, mailq Dec 25 '11 at 11:36

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4 Answers 4

How can I troubleshoot this and maybe a solution would be to set my frequency to something else, but which one?

NONE. Move to teh 5ghz band - less range (good), more frequencies (good) and rarer equipment (good). Your problems is not only all the wifi networks but all the stuff NOT being a WIFI network that STILL uses the 2.4 ghz band.

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Ok, ill do so and keep you in touch! Thanks. –  Jonathan Rioux Dec 2 '11 at 16:13

From the Wikipedia 802.11n - Backward Compatibility section:

"When 802.11g was released to share the band with existing 802.11b devices, it provided ways of ensuring coexistence between legacy, and successor devices. 802.11n extends the coexistence management to protect its transmissions from legacy devices, which include 802.11g, 802.11b and 802.11a. There are MAC and PHY level protection mechanisms as listed below:

  • PHY level protection: Mixed Mode Format protection (also known as L-SIG TXOP Protection): In mixed mode, each 802.11n transmission is always embedded in an 802.11a or 802.11g transmission. For 20 MHz transmissions, this embedding takes care of the protection with 802.11a and 802.11g. However, 802.11b devices still need CTS protection.
  • PHY level protection: Transmissions using a 40 MHz channel in the presence of 802.11a or 802.11g clients require using CTS protection on both 20 MHz halves of the 40 MHz channel, to prevent interference with legacy devices.
  • MAC level protection: An RTS/CTS frame exchange or CTS frame transmission at legacy rates can be used to protect subsequent 11n transmission.

"Even with protection, large discrepancies can exist between the throughput an 802.11n device can achieve in a greenfield network, compared to a mixed-mode network, when legacy devices are present. This is an extension of the 802.11b/802.11g coexistence problem."

Also see: Slowest wireless client dictates the connection quality of all others

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Not only do slowest clients dictate connection quality, but in my experimenting with radio links, the stations that you can receive but that cannot hear your signal really quash your throughput. We called this the "hidden transmitter effect". They block you from sending while transmitting and while they can run flat out transmitting to their partner, can effectively lock you out of being able to transmit at all. –  Fiasco Labs Dec 24 '11 at 20:31

You should definitely move to N if you can afford to. As Tomtom stated, there are many more channels available and the range is shorter (which will actually help in your case since you won't be fighting so many others farther away). There are many free tools available to see the different networks within range and what channels they are using. On windows, netstumbler is easiest for a casual peek, on *nix I use airodump. Once you've determined what channel is free (or close to it), determine your default gateway (ipconfig or ifconfig), open a browser and connect to that IP. This is your wireless router. You'll have to poke around a bit but you'll find the channel setting in there usually under a "wireless" tab. Although, most routers are configured to automatically select a channel with minimal noise by default so I'm not sure this will help tremendously.

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The ideal solution would be to use a simultaneous dual-band network. Unfortunately, if you don't already have a simultaneous dual-band router and/or laptop this will mean replacing all your equipment. Simultaneous dual-band wireless N will hop back and forth between 5 GHz and 2.4 GHz as needed for best speed.

The complexity of your router can also help - there are devices with different antenna configurations. MIMO (multiple in/multiple out) is much more robust with respect to noise, and more antennas is usually better. If you have a device that allows you to adjust the antennas you probably don't have MIMO.

The suggestion to use a router that automatically selects the least noisy channel is a decent one too. You may not have this turned on if your router supports it - it's worth checking. It may also be worth checking if your router supports DD-WRT or Tomato firmware, which will add that feature (and many more) even if you don't have them in the first place.

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The problem with switching firmware is tha t it doesn ot solve the problem. In my appartment I see more than two dozen 2.4ghz wifis as well as some blocked channels (microwaves work on 2.4 too). Switch to 5ghz and I am ALONE. This is TOTALLY MINE. Nothing you can switch to in 2.4ghz. –  TomTom Dec 2 '11 at 19:24

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