BTS_Tests: add TC_ms_pwr_ctrl_pf_ewma: test EWMA based power filtering

This test case is very similar to TC_ms_pwr_ctrl_constant(), but the
key difference that we simulate sharp UL RSSI changes between -50 dBm
and -100 dBm on each iteration.

The 'uplink-power-target' (-75 dBm) is right in the middle of the
change range, so with EWMA filtering and 80% smoothing it's expected
that all averaged UL RSSI values would be around -75 dBm.

It's expected that the Uplink power level remains constant, however
this test case fails at the moment.  The problem is that the IUT is
still quite sensitive to small deviations from 'uplink-power-target',
so ideally we should introduce a 'hysteresis' defining a range:

  ['target' - 'hysteresis' ... 'target' + 'hysteresis']

in which the MS power loop should not trigger any power changes.

For example, let's say:

  'uplink-power-target' is -75 dBm (default), and
  'hysteresis' is 8 dBm,

so then the range would be: -83 dBm ... -67 dBm.

Change-Id: I3be1a4a4a0ab7eebb9a930eee7039295c045a791
Depends: Iacedbd4d69d3d74e2499af5622a07a8af0423da0
Related: SYS#4916
1 file changed