Hi Hungtran (still in vietnam ? 🙂 )
satellite BTS shall be set to free running. it is stable. Some timers in the BSC shall be set to special values, to take into account the delay due to the distance earth-satellite-earth.
BSC PARAMETERS
T3168 = 1.5s
ROUND TRIP DELAY = 700ms
T GCH CORR = 700ms
T GCH ESTAB = 1000ms
BS CV MAX = 15
T3192 = 1000ms (if DRX TIMER MAX > 0 or EN DELAYED DL TBF REL = ENABLE)
But please liase with your TPM so he can confirm you those values.