Check:
-AMR radiolink timeout (ARLT)in all the BTSs, I´ve seen high dcr when this value is less than 20mS
-Check the dimensionning of AMR (pool-23) and FR/EFR(pool-20) CGR’s, if you don´t have enough circuits it is possible dcr
-Check In TCSM, the DL DTX setting, ON is only for Test purposes. Anyway since should be always OFF, check that TSL are OFF for all TCSM.