On Mon, Jun 01, 2020 at 05:10:14PM -0700, Matthew Wang wrote: > The roaming logic is currently too aggressive and full of holes. In > particular, the (arbitrary) values we currently assign to the roaming > difficulty are too small; an AP can reasonably move up or down 5dB in > RSSI in an enterprise environment even when the device is static. The > logic needs to be more resilient to these small fluctuations. > > The following notes describe each of the changes made and the rationale > behind it. > 1. Remove all short-circuiting and allow the roaming logic below to run > its course. This way we avoid overlooking important factors. > 2. Add a to_2ghz flag that indicates if we are moving from a 5ghz AP to > a 2ghz AP. This should increase the difficulty to roam in that > direction and mirror the to_5ghz flag. > 3. Adjust the min_diff upward across the board. Originally, we would > roam with a RSSI imporvement of 1dB in the weakest bucket and 5dB in > the strongest bucket. RSSI is fairly fickle and APs can easily > fluctuate by more than that in a normal enterprise environment. > Additionally, there should be more buckets. We currently stop > differentiating after the RSSI is at least -70dB. This is still > pretty weak, and the difficulty should continue to increase above > that. Move the threshold up to 4dB in the weakest bucket and 10dB in > the strongest bucket, and add two more buckets (up to -60dB). > 4. We adjust the roam difficulty up and down based on the estimated > throughput of the selected AP relative to the estimated throughput of > the current AP. Small gains or losses in estimated throughput should > not be rewarded or penalized as heavily as they are now since > estimated throughput is a hand-wavy measurement to begin with. Relax > these adjustments. This seems to prevent roaming from non-HT to HT AP if those APs have the same signal strength. This does not sound desirable. Being able to use HT will likely get better throughput and reduced airtime need. For example, the prefix_ht20_during_roam test case fails because of these. -- Jouni Malinen PGP id EFC895FA _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
