On Wed, Sep 15, 2010 at 3:39 AM, Bob Copeland <me@xxxxxxxxxxxxxxx> wrote: > On Tue, Sep 14, 2010 at 1:51 AM, Jonathan Guerin <jonathan@xxxxxxxxxxxx> wrote: >> as well as 1360 frames which came in with a negative CONTENTION_TIME. >> >> Ignoring the fact that some frames are coming up with a negative >> CONTENTION_TIME (which potentially points to another problem) > > How negative are these? Are you subtracting more for, say, txtime > than you should be? Actually, I've found that they were exactly one slot time negative (give or take 1us). That said, I was doing these calculations using the 802.11a OFDM spec timings. I looked at the driver and realised that SIFS is actually being initialised to 14us, whereas it should be set to 16us. This will also affect DIFS. Once I take these into consideration, they come up as approximately 4-5us out. Now that I think about it, it could make sense. With regards to the tx_time, I'm using the OFDM tx_time formula from the 802.11-2007 spec. I'm trying to lock down enough aspects of the timing in order to verify it. From what I've seen now, my txtime is almost always 4us short, but I can't work out why. I will get the code for the txtime when I get into my office, I don't have it on this PC. > > -- > Bob Copeland %% www.bobcopeland.com > Thanks, Jonathan -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
