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Use signal_poll noise information for roaming, if available

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Using average signal strength from the driver and hardcoded noise floor
does not look like an ideal design since there can be significant
differences in the driver-reported noise floor values. Furthermore, even
though the current noise floor is a snapshot from the driver, it is
common for drivers to use a noise floor value from a longer calibration
step and that should not prevent the driver provided value from being
used. This makes the comparisons of the signal strengths between the
current AP (signal_poll) and other APs (scan) more accurate.

As an example, test runs in home environment showed 5 dB difference
between the driver reported noise floor and the hardcoded value and this
could result in significant differences in estimated throughput
calculation.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2020-01-01 13:38:11 +02:00
parent f97baef254
commit f4f7600adf
1 changed files with 6 additions and 11 deletions
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17
wpa_supplicant/events.c
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@ -1672,17 +1672,11 @@ static void wpa_supplicant_rsn_preauth_scan_results(
}
static int wpas_get_snr_signal_info(u32 frequency, int avg_signal)
static int wpas_get_snr_signal_info(u32 frequency, int avg_signal, int noise)
{
int noise = IS_5GHZ(frequency) ?
DEFAULT_NOISE_FLOOR_5GHZ :
DEFAULT_NOISE_FLOOR_2GHZ;
/*
* Since we take the average beacon signal, we can't use
* the current noise measurement (average vs. snapshot),
* so use the default values instead.
*/
if (noise == WPA_INVALID_NOISE)
noise = IS_5GHZ(frequency) ? DEFAULT_NOISE_FLOOR_5GHZ :
DEFAULT_NOISE_FLOOR_2GHZ;
return avg_signal - noise;
}
@ -1784,7 +1778,8 @@ static int wpa_supplicant_need_to_roam(struct wpa_supplicant *wpa_s,
cur_level = si.avg_beacon_signal ? si.avg_beacon_signal :
si.avg_signal;
snr = wpas_get_snr_signal_info(si.frequency, cur_level);
snr = wpas_get_snr_signal_info(si.frequency, cur_level,
si.current_noise);
cur_est = wpas_get_est_throughput_from_bss_snr(wpa_s,
current_bss,