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hostapd: Beacon generation with Power Constraint IE - 11h TPC

RFC In review Srinivasan B 2 participants 2 messages Feb 4, 2013 – May 30, 2013

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Srinivasan B

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RFC 1/1 hostapd: Beacon generation with Power Constraint IE - 11h TPC

This patch includes modifications in hostapd to generate beacons and probe response packets with Power Constraint IE.

This patch is based on the initial design RFC proposed with subject "[RFC - v1 - design doc] hostapd: Beacon generation with Power Constraint IE - 11h TPC".

Changes from the proposed design:
------------------------------------------------
Design document proposes to imply TPC only for devices operating in U-NII 2 band. As per further analysis of beacons transmitted by Netgear, CISCO APs and few other APs in 802.11A mode, the power constraint IE is also included in beacons transmitted in U-NII 1, U-NII 3 bands. Hence power constraint IE is included in all beacons/probe response packets for devices operating in 80211A mode (without restricting to U-NII 2 band) and with 80211h flag enabled in hostapd.config

Signed-off-by Srinivasan <[email protected]>
---
 hostapd/config_file.c |    8 ++++++++
 hostapd/hostapd.conf  |    5 +++++
 src/ap/ap_config.h    |    3 +++
 src/ap/beacon.c       |   30 ++++++++++++++++++++++++++++++
 src/ap/ieee802_11.c   |    5 +++++
 5 files changed, 51 insertions(+), 0 deletions(-)
hostapd/config_file.c +8 -0
index 7b22dfd..b6a3b6e 100644
@@ -1224,6 +1224,12 @@ static int hostapd_config_check(struct hostapd_config *conf)
         return -1;
     }
 
+    if (conf->ieee80211h && !conf->ieee80211d) {
+        wpa_printf(MSG_ERROR, "Cannot enable IEEE 802.11h without "
+               "enabling 802.11d ");
+        return -1;
+    }
+
     for (i = 0; i < conf->num_bss; i++) {
         if (hostapd_config_check_bss(&conf->bss[i], conf))
             return -1;

@@ -1785,6 +1791,8 @@ static int hostapd_config_fill(struct hostapd_config *conf,
             conf->country[2] = ' ';
         } else if (os_strcmp(buf, "ieee80211d") == 0) {
             conf->ieee80211d = atoi(pos);
+        } else if (os_strcmp(buf, "ieee80211h") == 0) {
+            conf->ieee80211h = atoi(pos);
         } else if (os_strcmp(buf, "ieee8021x") == 0) {
             bss->ieee802_1x = atoi(pos);
         } else if (os_strcmp(buf, "eapol_version") == 0) {
hostapd/hostapd.conf +5 -0
index eca3996..759489f 100644
@@ -105,6 +105,11 @@ ssid=test
 # (default: 0 = disabled)
 #ieee80211d=1
 
+# Enable IEEE 802.11h. This is a partial support for 802.11h which
+# includes Power Constraint IE in beacon and prb response.
+# (default: 0 = disabled)
+#ieee80211h=1
+
 # Operation mode (a = IEEE 802.11a, b = IEEE 802.11b, g = IEEE 802.11g,
 # ad = IEEE 802.11ad (60 GHz); a/g options are used with IEEE 802.11n,

too, to

 # specify band)
src/ap/ap_config.h +3 -0
index 4742107..a0624b9 100644
@@ -460,6 +460,8 @@ struct hostapd_bss_config {
     int *sae_groups;
 };
 
+/* Default value for pwr constraint */
+#define DEFAULT_PWR_CONSTRAINT 0
 
 /**
  * struct hostapd_config - Per-radio interface configuration

@@ -495,6 +497,7 @@ struct hostapd_config {
               */
 
     int ieee80211d;
+    int ieee80211h;
 
     struct hostapd_tx_queue_params tx_queue[NUM_TX_QUEUES];
src/ap/beacon.c +24 -0
index 4c47c75..9749d45 100644
@@ -172,6 +172,30 @@ static u8 * hostapd_eid_country(struct hostapd_data *hapd, u8 *eid,
     return pos;
 }
 
+static u8 * hostapd_eid_pwr_constraint(struct hostapd_data *hapd, u8 *eid)
+{
+    u8 *pos = eid;
+
+    if (!hapd->iconf->ieee80211h ||
+        hapd->iface->current_mode == NULL ||
+        hapd->iface->current_mode->mode != HOSTAPD_MODE_IEEE80211A)
+        return eid;
+
+    /* CRDA provides reduced TX power than actual regulatory max TX power.
+     * Value of 0 to the Local Power constraint provides an opportunity
+     * for the client devices to operate at Power Limit provided by CRDA
+     * (for client devices
+     * "Local max TX pwr" = regul max TX pwr - Local pwr constraint)*/
+
+    /* Element ID */
+    *pos++ = WLAN_EID_PWR_CONSTRAINT;
+    /* Length */
+    *pos++ = 1;
+    /* Local Power Constraint */
+    *pos++ = DEFAULT_PWR_CONSTRAINT;
+
+    return pos;
+}
 
 static u8 * hostapd_eid_wpa(struct hostapd_data *hapd, u8 *eid, size_t

len)
{
@@ -242,6 +266,9 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,

     pos = hostapd_eid_country(hapd, pos, epos - pos);

+ /* Power Constraint element */
+ pos = hostapd_eid_pwr_constraint(hapd, pos);
+

     /* ERP Information element */
     pos = hostapd_eid_erp_info(hapd, pos);

@@ -631,6 +658,9 @@ void ieee802_11_set_beacon(struct hostapd_data *hapd)
tailpos = hostapd_eid_country(hapd, tailpos,
tail + BEACON_TAIL_BUF_SIZE - tailpos);

+ /* Power Constraint element */
+ tailpos = hostapd_eid_pwr_constraint(hapd, tailpos);
+

     /* ERP Information element */
     tailpos = hostapd_eid_erp_info(hapd, tailpos);
src/ap/ieee802_11.c +5 -0
index 79235df..2a4f758 100644
@@ -175,6 +175,11 @@ u16 hostapd_own_capab_info(struct hostapd_data *hapd, struct sta_info *sta,
         hapd->iface->num_sta_no_short_slot_time == 0)
         capab |= WLAN_CAPABILITY_SHORT_SLOT_TIME;
 
+    /* To Do: Also consider driver support for DFS to set Spectrum Mgmt*/
+    if (hapd->iface->current_mode &&
+        hapd->iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
+        hapd->iconf->ieee80211h)
+        capab |= WLAN_CAPABILITY_SPECTRUM_MGMT;
     return capab;
 }
#1 lore raw

Hie, I need help generating a beacon with CF parameter. I want to store an alphanumeric value in the unused bits of the lenght field of that parameter and then have clients only connecting to that AP if there are many other broadcasts. Please help with ideas. Which files do i need to change, etc

Thanx

Que