On Wed, 2011-08-24 at 12:02 -0700, Thomas Pedersen wrote: > Hi I'm adding HT support for mesh. > > This patchset is pretty basic, and relies on Alexander Simon's HT IE helper > funtions. Ok. I'm pretty happy with those, but haven't seen the latest version of the IBSS parts. > No channel type negotiation takes place, and the HT info IE from the > peer is not even read. That seems odd. > In practice, nodes with mismatched channel types seem to communicate fine, > although throughput is affected (TX from HT40 -> HT20 is the worst case). That would highly depend on rate control? Or do we do some HT capability/operation IE stuff and figure this out? Still seems a little strange. > We measured these data rates in our (widely uncontrolled) office environment > using the ath9k_htc driver: > > A\B NO HT HT20 HT40+ > NO HT r: 54Mb/s r: MCS 13 r: MCS 13 > D: 20Mb/s D: 16Mb/s D: 16Mb/s > HT20 r: 54Mb/s r: MCS 13 r: MCS 13 > D: 22.5Mb/s D: 18.5Mb/s D: 15Mb/s > HT40+ r: 54Mb/s r: MCS 0 r: MCS 12 @ 40Mhz > D: 22Mb/s D: 5.1Mb/s D: 20Mb/s > > r: rate reported by minstrel. > D: TX throughput (A -> B using 'iperf -c <B> -u -b400M') > > Is it odd that even HT40+ -> HT40+ is not any better than the non-HT case? Are > we doing something wrong? Are you surprised that mismatched channel types work > at all? Not surprised, but won't be efficient, especially when some device uses a dumber rate control than minstrel :) > So currently, our channel type is always just whatever the user configured > through iw. The path selection algorithm should be able to compensate by > detecting faster links and adjusting the respective mpaths accordingly. > > If this is completely wrong, I would appreciate any suggestions on the right > way to handle mesh peers with different channel types. I have no idea. The channel type stuff seems a little fishy though. johannes -- 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
