SD drops.
Kindly check the following.
1- Site/Sector is stable means it should not be fluctuating.
2-TRXs are stable,Not fluctuating or not being restart frequently.
3-DL quality of the Segement/TRXs.(Q5)
if these are degraded then replace TRXs and check VSWR should be good one.
4- Adjust TA value (try to decrease)
5- HYS value can be set 10 if this is Nokia BTS.
Thanks