power_control: make P_CON_INTERVAL parameter configurable

Change-Id: I6e0fae81cc60f708e49d5eb8dfc0bbcad926b18f
Related: SYS#4918

1 files changed, 22 insertions, 1 deletions

diff --git a/doc/manuals/chapters/power_control.adoc b/doc/manuals/chapters/power_control.adoc
index dbe2d1381..4c1a275b8 100644
--- a/doc/manuals/chapters/power_control.adoc
+++ b/doc/manuals/chapters/power_control.adoc
@@ -88,6 +88,7 @@ OsmoBSC(config-ms-power-ctrl)# list with-flags
 ...
   . l.  mode (static|dyn-bts) [reset]
   . l.  bs-power (static|dyn-max) <0-30>
+  . lv  ctrl-interval <0-31>
   . lv  step-size inc <2-6> red <2-4>
   . lv  rxlev-thresh lower <0-63> upper <0-63>
   . lv  rxqual-thresh lower <0-7> upper <0-7>
@@ -135,6 +136,27 @@ that allows to configure the maximum BS power reduction value in `dyn-bts` mode,
 and a fixed power reduction value in `static` mode.  In the later case, no
 attenuation (0 dB) is applied by default (full power).
 
+==== Power control interval
+
+Having requested a transmit power level, the MS/BS power control loop may optionally
+by suspended for a certain number of SACCH multiframes defined by VTY parameter
+`ctrl-interval`.  Given that SACCH is relatively slow and transmission of a data block
+takes 480 ms, suspension allows an observation of the effect of one power control
+decision before initiating the next one.
+
+----
+OsmoBSC(config-bs-power-ctrl)# ctrl-interval ?
+  <0-31>  P_CON_INTERVAL, in units of 2 SACCH periods (0.96 seconds)
+----
+
+By default, the suspension interval is set to 0 for both MS/BS power control loops,
+therefore the power control decision is taken every 480 ms (one SACCH block period).
+Setting `ctrl-interval` to 1 increases the interval to 960 ms, so basically every
+second Uplink SACCH block is skipped;  value 2 corresponds to the interval of
+1920 ms, so 3/4 received SACCH blocks are skipped.
+
+3GPP TS 45.008 briefly mentiones this parameter in table A.1 (P_Con_INTERVAL).
+
 ==== Power change step size
 
 In order to slow down the reactivity of the power control loop and thus make it more
@@ -302,7 +324,6 @@ network
 <4> Osmocom specific EWMA is applied to RxQual values with smoothing factor = 50% (beta=0.5).
 <5> RxQual: Hreqave and Hreqt values: 2 out of 3 SACCH blocks produce an averaged measurement.
 
-// TODO: Document P_Con_INTERVAL (not implemented yet)
 // TODO: Document other power control parameters:
 //		OsmoBSC(config-net-bts)# ms max power <0-40>
 //		OsmoBSC(config-net-bts-trx)# max_power_red <0-100>