Sorry for my late response.
Yes, it’s continuously decreasing (Dedicated mode).
At first, EN_BS_PC was ENABLE.
And other parameters :
L_RXQUAL_DL_P = 30 x0.1
U_RXQUAL_DL_P = 30 x0.1
A LEV PC = 4 SACCH
A QUAL PC = 4 SACCH
When I disabled EN_BS_PC, then the signal strength was more stable.
I concluded that in the area where there were only few sites (Suburban Area), it’s okay to disable power control (EN_BS_PC and EN_MS_PC), but not in the crowded sites (Urban Area) coz it will emerge an interference.
As I know, if Power control is disabled (EN_BS_PC and EN_MS_PC), the MS will transmit with max power. If PC is ENABLED, MS will adjust the power transmitted regarding to the command from BSC. BSC will send command to MS about how strength the MS must transmit the power.