On 26.11.2009 19:18 Johannes Berg wrote: > I discussed this with Alina a while back (in private, she didn't want to > discuss in English) and we came to the conclusion that set_coverage() > should be done like 802.11-2007 17.3.8.6 specifies for 5ghz, but could > be done for 2.4ghz as well. Thoughts? It would also allow us to actually > advertise that to compatible clients. If I understand the standard correctly, it means the slottime should be (9 + propagation_delay), which equals (9 + distance / 300). And that's basically the same as the formula from Madwifi's athctrl I wanted to use: int slottime = 9 + (distance / 300) + ((distance % 300) ? 1 : 0); The main difference is that the coverage classes have an upper limit under 28km, but I don't see the point in artifically limiting maximum link distance (30km link could be done with big enough antennas). And I would prefer if the userspace API operated with distance rather than coverage classes, because it allows the user to set it correctly without reading a thousand page document. The coverage class could be then calculated for use in beacons as you proposed. Of course, in this case we would be constrained by the maximum coverage class in the standard. Lukas Turek
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