Document bgscan configuration options

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

wpa_supplicant/wpa_supplicant.conf

@@ -494,6 +494,23 @@ fast_reauth=1
 # set, scan results that do not match any of the specified frequencies are not
 # considered when selecting a BSS.
 #
+# bgscan: Background scanning
+# wpa_supplicant behavior for background scanning can be specified by
+# configuring a bgscan module. These modules are responsible for requesting
+# background scans for the purpose of roaming within an ESS (i.e., within a
+# single network block with all the APs using the same SSID). The bgscan
+# parameter uses following format: "<bgscan module name>:<module parameters>"
+# Following bgscan modules are available:
+# simple - Periodic background scans based on signal strength
+# bgscan="simple:<short bgscan interval in seconds>:<signal strength threshold>:
+# <long interval>"
+# bgscan="simple:30:-45:300"
+# learn - Learn channels used by the network and try to avoid bgscans on other
+# channels (experimental)
+# bgscan="learn:<short bgscan interval in seconds>:<signal strength threshold>:
+# <long interval>[:<database file name>]"
+# bgscan="learn:30:-45:300:/etc/wpa_supplicant/network1.bgscan"
+#
 # proto: list of accepted protocols
 # WPA = WPA/IEEE 802.11i/D3.0
 # RSN = WPA2/IEEE 802.11i (also WPA2 can be used as an alias for RSN)