Hi guys,
Today I performed receive sensitivity tests for wrt54gl with openwrt 8.09.1 (2.4) and the svn trunk (2.6).
My test was very simple:

2 WRT54GL APs in 2 different, distant rooms (one of which made out of concrete with no windows) connected with a long cable (no antennas connected)
1 unit with 8.09.1-2.4 running in AP mode and sending the default 10 beacons per second and 1 unit with the svn trunk (and later with 8.09.1-2.4) running in monitor mode
My cable had 3 spots in which I used attenuators. One - very close to the antenna of the AP (-40dBm), one in the center (another -40dBm) and a variable attenuator near the receiving unit. The cable itself lost 2-3dB.

I verified the signal strength at the receiving end using a really expensive spectrum analyzer I borrowed from a friend.

My test was simple - how many beacons can I see at which signal strength (tested with a simple tcpdump test)
Since the AP is sending out the signal at 20dBm, I managed to get all beacons at -60dBm (20-40-40), then I started reducing the signal further, the unit stopped receiving beacons completely as soon as I reached -77dBm and at -75dBm I got about 10% of the beacons (horrible as well...)
According to Linksys WRT54GL should have a receive sensitivity of -99dBm @ 1mbit, according to my tests - I get no signal at -77dBm, that's 23dB difference...!
I performed the same test with the vanilla 8.09.1-2.4 with similar results.

My questions are:
1. Is it a known issue?
2. Did I do something wrong in my test?
3. If wrt54GL is not that good when it comes to sensitivity - which AP has the best receive sensitivity and is supported by openwrt?? (I don't care for the transmission power, I am using an amp anyway).

I would really appreciate any help, I am pretty stuck here and I never believed that receive sensitivity will be my problem
Thanks in advance.

(Last edited by alfred_m on 23 Aug 2009, 08:17)

one aspect undocumented in your description of the test is the modulation bit rate.
Are both sides allowed to renegotiate the bit rate (wireless config settings) when the signal gets weaker.
Install the wl package and check ´ wl rate´ on either side during the test.

Thanks,
I did not negotiate any bit rate as there was no actual connection, I simply used the receiving AP in monitor mode and checked how many beacons I am at which attenuation level.