Use estimated throughput to improve roaming selection

Previously, within-ESS roaming was skipped if the selected BSS did not
have a higher signal strength than the current BSS regardless of AP
capabilities. This could result in not moving to a BSS that would
provide higher throughput, e.g., due to larger channel bandwidth or
higher rates (HT/VHT MCS).

Use estimated throughput information from scan result processing to
allow within-ESS roaming if the selected BSS is likely to provide better
throughput even if the current BSS has larger RSSI.

Signed-off-by: Jouni Malinen <j@w1.fi>

wpa_supplicant/events.c

@@ -1223,10 +1223,14 @@ static int wpa_supplicant_need_to_roam(struct wpa_supplicant *wpa_s,
 
 #ifndef CONFIG_NO_ROAMING
 	wpa_dbg(wpa_s, MSG_DEBUG, "Considering within-ESS reassociation");
-	wpa_dbg(wpa_s, MSG_DEBUG, "Current BSS: " MACSTR " level=%d",
-		MAC2STR(current_bss->bssid), current_bss->level);
-	wpa_dbg(wpa_s, MSG_DEBUG, "Selected BSS: " MACSTR " level=%d",
-		MAC2STR(selected->bssid), selected->level);
+	wpa_dbg(wpa_s, MSG_DEBUG, "Current BSS: " MACSTR
+		" level=%d snr=%d est_throughput=%u",
+		MAC2STR(current_bss->bssid), current_bss->level,
+		current_bss->snr, current_bss->est_throughput);
+	wpa_dbg(wpa_s, MSG_DEBUG, "Selected BSS: " MACSTR
+		" level=%d snr=%d est_throughput=%u",
+		MAC2STR(selected->bssid), selected->level,
+		selected->snr, selected->est_throughput);
 
 	if (wpa_s->current_ssid->bssid_set &&
 	    os_memcmp(selected->bssid, wpa_s->current_ssid->bssid, ETH_ALEN) ==
@@ -1236,6 +1240,12 @@ static int wpa_supplicant_need_to_roam(struct wpa_supplicant *wpa_s,
 		return 1;
 	}
 
+	if (selected->est_throughput > current_bss->est_throughput + 5000) {
+		wpa_dbg(wpa_s, MSG_DEBUG,
+			"Allow reassociation - selected BSS has better estimated throughput");
+		return 1;
+	}
+
 	if (current_bss->level < 0 && current_bss->level > selected->level) {
 		wpa_dbg(wpa_s, MSG_DEBUG, "Skip roam - Current BSS has better "
 			"signal level");