How to Test the Strength of a WiFi Connection

Introduction

I bought a new WiFi router that claimed to have special enhancements to boost the signal. I wanted to see how much of a boost was created. Here's how it was accomplished:

Setup

I found that iwconfig prints out a lot of data. Here's an example:

lo        no wireless extensions.

eth0      no wireless extensions.

wlan0     IEEE 802.11bg  ESSID:"..." 

          Mode:Managed  Frequency:2.437 GHz  Access Point: 00:11:22:33:44:55  

          Bit Rate=24 Mb/s   Tx-Power=20 dBm  

          Retry  long limit:7   RTS thr:off   Fragment thr:off

          Power Management:off

          Link Quality=29/70  Signal level=-81 dBm 

          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0

          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

I'm not sure what it all means but Link Quality and Signal level look very interesting. So, I wrote the following script:

#/bin/bash

while [ 1 ]

do

    iwconfig 2>&1|grep Link

    sleep 1

done

Now, I get something interesting every second. It looked something like this:

          Link Quality=31/70  Signal level=-79 dBm 

          Link Quality=31/70  Signal level=-79 dBm 

          Link Quality=30/70  Signal level=-80 dBm 

          Link Quality=29/70  Signal level=-81 dBm 

          Link Quality=31/70  Signal level=-79 dBm 

          Link Quality=30/70  Signal level=-80 dBm 

          Link Quality=31/70  Signal level=-79 dBm

Notice that the signal is in dBm and is always negative. Also notice that Link Quality went up as signal became less negative.

The Test

I walked around the house while watching the Link Quality number change. I noticed a huge difference when a wall was in the way. It was even possible to determine the outer boundaries of the signal. There may be other ways to view this information, but this was very easy for me.