Retransmission Behaviour

Live forum: http://rt2x00.serialmonkey.com/viewtopic.php?t=4453

erockman

19-11-2007 17:17:35

Hi all,

I have an in-depth question regarding the behaviour of the rt2560 mac controller

Situation
When setting 802.11g OFDM modes (12M,24M,36M,48M,54M) with "iwconfig ra0 rate xy fixed"

Problem
If a unicast frame transmission is not successful (ACK timeout for whatever reason) the following MAC retransmissions are always done at [bgrqru2l4]the next lower OFDM mode[/bgrqru2l4].

AFAIK this (quite smart) feature is not part of the IEEE standard spec, for our measurement testbed we need a way to turn it off i.e. strictly fixing the rate is what we want

So this is not about setting the OFDM rates that are used in the first place, we need to turn off the "retransmission-rate-fallback" feature.

I am already quite familiar with the driver source and my guess is that changing a BBP or CSR register value could do the trick but until now I was not able to pull it off.....

is somebody hanging around here who has more indepth-info on the rt2560 mac controller?

Background info
HW rt2500 pci 802.11b/g based model MSI PC54G2 with RT2560F
kernel 2.6.22.3
rt2500-cvs-2007080310

every hint is [igrqru2l4]greatly[/igrqru2l4] appreciated )

greetings from Austria!

Paul Fuxjäger
Forschungszentrum Telekommunikation Wien
http//www.ftw.at