hamdi,
4 extra TS on a 4/4/4 BTS gives :
4 x 4 = 16 extra nibbles
3(1bc + 2sd) x 3 = 9 bonus nibbles
=> 25 “extra” nibbles available
1 MS in MCS9 needs 18 nibbles. That’s 4 basic nibbles + 14 “extra” nibbles.
So with 4 extra TS, you can have 1 MS in MCS9, or 2 MS with MCS7, etc…
If you cinlude free basic nibbles from other radio timeslots, then you might reach 2 MS with MCS9, etc…