Ok. Thank you On Mon, Jan 17, 2011 at 14:42, Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx> wrote: > On Mon, 2011-01-17 at 14:33 +0200, ext Kahn, Gery wrote: >> Does it worth to have different value for 5GHz? >> > > I guess the 100ms value benefits 2.4GHz passive scanning as well, does > it not? In 2.4GHz band there are usually very few channels passive > scanned (mostly channels 12 and 13 in the 00 region) so the cost of this > increased wait time is quite little. > > -Juuso > >> On Mon, Jan 17, 2011 at 13:32, Â<juuso.oikarinen@xxxxxxxxx> wrote: >> > From: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx> >> > >> > The passive scan channel dwell time currently used is 30ms-60ms. A typical >> > beacon interval for AP's is 100ms. This leads to a ~30% worst-case probability >> > of finding an AP via passive scanning. >> > >> > For 5GHz bands for DFS frequencies passive scanning is the only scanning >> > option. Hence for these, the probability of finding an AP is very low. >> > >> > To fix this, increase the passive channel scan dwell times (also the early >> > leave value, as 5GHz channels are still typically very silent.) Use a value >> > of 100ms, because that covers most typical AP configurations. >> > >> > Based on testing the probability of finding an AP (102.4ms beacon interval) on >> > a single scan round are as follows (based on 100 iterations): >> > >> > dwell min/max (ms) Â | probability >> > ---------------------+------------ >> > 30/60 Â Â Â Â Â Â Â Â| 35% >> > 60/60 Â Â Â Â Â Â Â Â| 56% >> > 80/80 Â Â Â Â Â Â Â Â| 77% >> > 100/100 Â Â Â Â Â Â Â| 100% >> > >> > Total scan times now and after the change: >> > >> > Region | Before (s) | After (s) >> > -------+------------+---------- >> > 00 Â Â | 0.77 Â Â Â | 1.48 >> > FI Â Â | 0.95 Â Â Â | 2.01 >> > US Â Â | 0.91 Â Â Â | 1.76 >> > >> > Signed-off-by: Juuso Oikarinen <juuso.oikarinen@xxxxxxxxx> >> > --- > > -- 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
