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ACS: Allow selecting a better channel when using 40/80/160 MHz

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When considering a channel for a bandwidth of 40/80/160 MHZ on the 5 GHz
or 6 GHz band, allow selecting one of the other channels in the segment
instead of the first one. This is done only if the other channel's
interference_factor is lower than the first one's.

Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
This commit is contained in:
Nicolas Escande 2022-04-27 15:37:02 +02:00 • committed by Jouni Malinen
parent 472101684b
commit 4cb23b66d6
1 changed files with 23 additions and 2 deletions
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25
src/ap/acs.c
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@ -719,7 +719,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
struct hostapd_channel_data **ideal_chan, struct hostapd_channel_data **ideal_chan,
long double *ideal_factor) long double *ideal_factor)
{ {
struct hostapd_channel_data *chan, *adj_chan = NULL; struct hostapd_channel_data *chan, *adj_chan = NULL, *best;
long double factor; long double factor;
int i, j; int i, j;
unsigned int k; unsigned int k;
@ -727,8 +727,9 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
for (i = 0; i < mode->num_channels; i++) { for (i = 0; i < mode->num_channels; i++) {
double total_weight; double total_weight;
struct acs_bias *bias, tmp_bias; struct acs_bias *bias, tmp_bias;
bool update_best = true;
chan = &mode->channels[i]; best = chan = &mode->channels[i];
/* Since in the current ACS implementation the first channel is /* Since in the current ACS implementation the first channel is
* always a primary channel, skip channels not available as * always a primary channel, skip channels not available as
@ -815,7 +816,15 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
if (acs_usable_chan(adj_chan)) { if (acs_usable_chan(adj_chan)) {
factor += adj_chan->interference_factor; factor += adj_chan->interference_factor;
total_weight += 1; total_weight += 1;
} else {
update_best = false;
} }
/* find the best channel in this segment */
if (update_best &&
adj_chan->interference_factor <
best->interference_factor)
best = adj_chan;
} }
if (j != n_chans) { if (j != n_chans) {
@ -824,6 +833,18 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
continue; continue;
} }
/* If the AP is in the 5 GHz or 6 GHz band, lets prefer a less
* crowded primary channel if one was found in the segment */
if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
chan != best) {
wpa_printf(MSG_DEBUG,
"ACS: promoting channel %d over %d (less interference %Lg/%Lg)",
best->chan, chan->chan,
chan->interference_factor,
best->interference_factor);
chan = best;
}
/* 2.4 GHz has overlapping 20 MHz channels. Include adjacent /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
* channel interference factor. */ * channel interference factor. */
if (is_24ghz_mode(mode->mode)) { if (is_24ghz_mode(mode->mode)) {