#endif /* CONFIG_WPS_NFC */
+#ifdef CONFIG_ACS
+static int hostapd_config_parse_acs_chan_bias(struct hostapd_config *conf,
+ char *pos)
+{
+ struct acs_bias *bias = NULL, *tmp;
+ unsigned int num = 0;
+ char *end;
+
+ while (*pos) {
+ tmp = os_realloc_array(bias, num + 1, sizeof(*bias));
+ if (!tmp)
+ goto fail;
+ bias = tmp;
+
+ bias[num].channel = atoi(pos);
+ if (bias[num].channel <= 0)
+ goto fail;
+ pos = os_strchr(pos, ':');
+ if (!pos)
+ goto fail;
+ pos++;
+ bias[num].bias = strtod(pos, &end);
+ if (end == pos || bias[num].bias < 0.0)
+ goto fail;
+ pos = end;
+ if (*pos != ' ' && *pos != '\0')
+ goto fail;
+ num++;
+ }
+
+ os_free(conf->acs_chan_bias);
+ conf->acs_chan_bias = bias;
+ conf->num_acs_chan_bias = num;
+
+ return 0;
+fail:
+ os_free(bias);
+ return -1;
+}
+#endif /* CONFIG_ACS */
+
+
static int hostapd_config_fill(struct hostapd_config *conf,
struct hostapd_bss_config *bss,
char *buf, char *pos, int line)
return 1;
}
conf->acs_num_scans = val;
+ } else if (os_strcmp(buf, "acs_chan_bias") == 0) {
+ if (hostapd_config_parse_acs_chan_bias(conf, pos)) {
+ wpa_printf(MSG_ERROR, "Line %d: invalid acs_chan_bias",
+ line);
+ return -1;
+ }
#endif /* CONFIG_ACS */
} else if (os_strcmp(buf, "dtim_period") == 0) {
bss->dtim_period = atoi(pos);
# interference that may help choosing a better channel. This can also help fine
# tune the ACS scan time in case a driver has different scan dwell times.
#
+# acs_chan_bias is a space-separated list of <channel>:<bias> pairs. It can be
+# used to increase (or decrease) the likelihood of a specific channel to be
+# selected by the ACS algorithm. The total interference factor for each channel
+# gets multiplied by the specified bias value before finding the channel with
+# the lowest value. In other words, values between 0.0 and 1.0 can be used to
+# make a channel more likely to be picked while values larger than 1.0 make the
+# specified channel less likely to be picked. This can be used, e.g., to prefer
+# the commonly used 2.4 GHz band channels 1, 6, and 11 (which is the default
+# behavior on 2.4 GHz band if no acs_chan_bias parameter is specified).
+#
# Defaults:
#acs_num_scans=5
+#acs_chan_bias=1:0.8 6:0.8 11:0.8
# Channel list restriction. This option allows hostapd to select one of the
# provided channels when a channel should be automatically selected.
}
+static int is_24ghz_mode(enum hostapd_hw_mode mode)
+{
+ return mode == HOSTAPD_MODE_IEEE80211B ||
+ mode == HOSTAPD_MODE_IEEE80211G;
+}
+
+
+static int is_common_24ghz_chan(int chan)
+{
+ return chan == 1 || chan == 6 || chan == 11;
+}
+
+
#ifndef ACS_ADJ_WEIGHT
#define ACS_ADJ_WEIGHT 0.85
#endif /* ACS_ADJ_WEIGHT */
#define ACS_NEXT_ADJ_WEIGHT 0.55
#endif /* ACS_NEXT_ADJ_WEIGHT */
+#ifndef ACS_24GHZ_PREFER_1_6_11
+/*
+ * Select commonly used channels 1, 6, 11 by default even if a neighboring
+ * channel has a smaller interference factor as long as it is not better by more
+ * than this multiplier.
+ */
+#define ACS_24GHZ_PREFER_1_6_11 0.8
+#endif /* ACS_24GHZ_PREFER_1_6_11 */
+
/*
* At this point it's assumed chan->interface_factor has been computed.
* This function should be reusable regardless of interference computation
long double factor, ideal_factor = 0;
int i, j;
int n_chans = 1;
+ unsigned int k;
/* TODO: HT40- support */
for (i = 0; i < iface->current_mode->num_channels; i++) {
double total_weight;
+ struct acs_bias *bias, tmp_bias;
chan = &iface->current_mode->channels[i];
/* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
* channel interference factor. */
- if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B ||
- iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) {
+ if (is_24ghz_mode(iface->current_mode->mode)) {
for (j = 0; j < n_chans; j++) {
adj_chan = acs_find_chan(iface, chan->freq +
(j * 20) - 5);
factor /= total_weight;
- wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg",
- chan->chan, factor);
+ bias = NULL;
+ if (iface->conf->acs_chan_bias) {
+ for (k = 0; k < iface->conf->num_acs_chan_bias; k++) {
+ bias = &iface->conf->acs_chan_bias[k];
+ if (bias->channel == chan->chan)
+ break;
+ bias = NULL;
+ }
+ } else if (is_24ghz_mode(iface->current_mode->mode) &&
+ is_common_24ghz_chan(chan->chan)) {
+ tmp_bias.channel = chan->chan;
+ tmp_bias.bias = ACS_24GHZ_PREFER_1_6_11;
+ bias = &tmp_bias;
+ }
+
+ if (bias) {
+ factor *= bias->bias;
+ wpa_printf(MSG_DEBUG,
+ "ACS: * channel %d: total interference = %Lg (%f bias)",
+ chan->chan, factor, bias->bias);
+ } else {
+ wpa_printf(MSG_DEBUG,
+ "ACS: * channel %d: total interference = %Lg",
+ chan->chan, factor);
+ }
if (acs_usable_chan(chan) &&
(!ideal_chan || factor < ideal_factor)) {
os_free(conf->basic_rates);
os_free(conf->chanlist);
os_free(conf->driver_params);
+#ifdef CONFIG_ACS
+ os_free(conf->acs_chan_bias);
+#endif /* CONFIG_ACS */
os_free(conf);
}
#ifdef CONFIG_ACS
unsigned int acs_num_scans;
+ struct acs_bias {
+ int channel;
+ double bias;
+ } *acs_chan_bias;
+ unsigned int num_acs_chan_bias;
#endif /* CONFIG_ACS */
};