band-steering: add band-steering component

This adds a new band-steering component to usteer.

With band-steering enabled, usteer will attempt to move clients with a
consistently good SNR / signal from 2.4 GHz to the 5 GHz band.

In contrast to existing policies usteer tracks, band-steering is
non-invasive and will not lead to forceful connection termination.

Signed-off-by: David Bauer <mail@david-bauer.net>

openwrt/usteer/files/etc/config/usteer

@@ -117,6 +117,14 @@ config usteer
 	# Reason code on client kick based on channel load (default: WLAN_REASON_DISASSOC_AP_BUSY)
 	#option load_kick_reason_code 5
 
+	# Attempting to steer clients to a higher frequency-band every n ms.
+	# A value of 0 disabled band-steering.
+	#option band_steering_interval 120000
+
+	# Minimal SNR or absolute signal a device has to maintain over band_steering_interval to be
+	# steered to a higher frequency band
+	#option band_steering_min_snr -60
+
 	# Script to run after bringing up a node
 	#option node_up_script ''
 

openwrt/usteer/files/etc/init.d/usteer

@@ -85,6 +85,7 @@ uci_usteer() {
 		roam_kick_delay roam_scan_tries roam_scan_timeout \
 		roam_scan_snr roam_scan_interval \
 		roam_trigger_snr roam_trigger_interval \
+		band_steering_interval band_steering_min_snr \
 		load_kick_threshold load_kick_delay load_kick_min_clients \
 		load_kick_reason_code
 	do