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SME: Optimize OBSS scanning 

Include only the potentially affected channel range in OBSS scans to
reduce the amount of offchannel time needed for scanning when requested
by the AP.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2014-12-22 22:07:03 +02:00
parent 0acc2c809d
commit d97a3c4885
2 changed files with 55 additions and 7 deletions
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59
wpa_supplicant/sme.c
View File

@ -1253,28 +1253,72 @@ static struct hostapd_hw_modes * get_mode(struct hostapd_hw_modes *modes,
}
static void wpa_setband_scan_freqs_list(struct wpa_supplicant *wpa_s,
enum hostapd_hw_mode band,
struct wpa_driver_scan_params *params)
static void wpa_obss_scan_freqs_list(struct wpa_supplicant *wpa_s,
struct wpa_driver_scan_params *params)
{
/* Include only supported channels for the specified band */
/* Include only affected channels */
struct hostapd_hw_modes *mode;
int count, i;
int start, end;
mode = get_mode(wpa_s->hw.modes, wpa_s->hw.num_modes, band);
mode = get_mode(wpa_s->hw.modes, wpa_s->hw.num_modes,
HOSTAPD_MODE_IEEE80211G);
if (mode == NULL) {
/* No channels supported in this band - use empty list */
params->freqs = os_zalloc(sizeof(int));
return;
}
if (wpa_s->sme.ht_sec_chan == HT_SEC_CHAN_UNKNOWN &&
wpa_s->current_bss) {
const u8 *ie;
ie = wpa_bss_get_ie(wpa_s->current_bss, WLAN_EID_HT_OPERATION);
if (ie && ie[1] >= 2) {
u8 o;
o = ie[3] & HT_INFO_HT_PARAM_SECONDARY_CHNL_OFF_MASK;
if (o == HT_INFO_HT_PARAM_SECONDARY_CHNL_ABOVE)
wpa_s->sme.ht_sec_chan = HT_SEC_CHAN_ABOVE;
else if (o == HT_INFO_HT_PARAM_SECONDARY_CHNL_BELOW)
wpa_s->sme.ht_sec_chan = HT_SEC_CHAN_BELOW;
}
}
start = wpa_s->assoc_freq - 10;
end = wpa_s->assoc_freq + 10;
switch (wpa_s->sme.ht_sec_chan) {
case HT_SEC_CHAN_UNKNOWN:
/* HT40+ possible on channels 1..9 */
if (wpa_s->assoc_freq <= 2452)
start -= 20;
/* HT40- possible on channels 5-13 */
if (wpa_s->assoc_freq >= 2432)
end += 20;
break;
case HT_SEC_CHAN_ABOVE:
end += 20;
break;
case HT_SEC_CHAN_BELOW:
start -= 20;
break;
}
wpa_printf(MSG_DEBUG,
"OBSS: assoc_freq %d possible affected range %d-%d",
wpa_s->assoc_freq, start, end);
params->freqs = os_calloc(mode->num_channels + 1, sizeof(int));
if (params->freqs == NULL)
return;
for (count = 0, i = 0; i < mode->num_channels; i++) {
int freq;
if (mode->channels[i].flag & HOSTAPD_CHAN_DISABLED)
continue;
params->freqs[count++] = mode->channels[i].freq;
freq = mode->channels[i].freq;
if (freq - 10 >= end || freq + 10 <= start)
continue; /* not affected */
params->freqs[count++] = freq;
}
}
@ -1290,7 +1334,7 @@ static void sme_obss_scan_timeout(void *eloop_ctx, void *timeout_ctx)
}
os_memset(&params, 0, sizeof(params));
wpa_setband_scan_freqs_list(wpa_s, HOSTAPD_MODE_IEEE80211G, &params);
wpa_obss_scan_freqs_list(wpa_s, &params);
params.low_priority = 1;
wpa_printf(MSG_DEBUG, "SME OBSS: Request an OBSS scan");
@ -1315,6 +1359,7 @@ void sme_sched_obss_scan(struct wpa_supplicant *wpa_s, int enable)
eloop_cancel_timeout(sme_obss_scan_timeout, wpa_s, NULL);
wpa_s->sme.sched_obss_scan = 0;
wpa_s->sme.ht_sec_chan = HT_SEC_CHAN_UNKNOWN;
if (!enable)
return;

3
wpa_supplicant/wpa_supplicant_i.h
View File

@ -675,6 +675,9 @@ struct wpa_supplicant {
* SA Query transaction identifiers */
struct os_reltime sa_query_start;
struct os_reltime last_unprot_disconnect;
enum { HT_SEC_CHAN_UNKNOWN,
HT_SEC_CHAN_ABOVE,
HT_SEC_CHAN_BELOW } ht_sec_chan;
u8 sched_obss_scan;
u16 obss_scan_int;
u16 bss_max_idle_period;