wireless link quality determines connection??

[punter]

Hi,

I have my laptop and PC setup to connect on wireless using ad-hoc mode.
Whenever the two are close to each other, the connection is fine.... but whenever I move slightly further away I lose all connection!

Now, I know you can't connect when you have 0 signal.... but why can't I connect when I have 64% link quality ??

[no_hope]

The term "link quality" is deceptive. Without going into too much detail, SNR (signal-to-noise ratio) is what actually determines how much data you can send on a channel. SNR is the ratio of power at which you receive the data signal over the power of ambient environmental noise. The higher the SNR, the higher the data rate, the better your channel. This is the intuition for link quality.

The problem is that SNR is difficult to measure. So most cards instead report a ratio of the sum of actual signal power and noise power over some constant (noise floor). Thus, the stronger your signal is, the higher the "link quality". That is good. However by that equation, increasing noise also increases link quality. I.e. you could have 100% link quality that is entirely due to noise.

Even worse, link quality reported by iwconfig is an average and in ad-hoc networks may have little to do with the link quality to a particular peer.

To address poor signal quality you could try the following:

• don't use ad-hoc mode, it can be very unreliable even in good conditions
  
• try changing the channel
  
• try using 802.11a instead of 802.11bg (802.11a has shorter distance, but fewer things interfere with it)
  
• try fixing the rate at 1Mbps on all your machines with iwconfig
  
• fiddle with antenna locations and orientation
  
• buy/make higher gain (bigger) antennas
  
• try buying a good access point (they sometimes have better antennas)
  
• try using 802.11b it's more resilient sometimes (not sure)
  
• make sure all cards use maximum transmit power (Intel cards in particular)
  
• enable RTS/CTS (long shot)