From this data,what I can conclude is:
1.This cell is either at LA boundary or overshooting at LA boundary beacuse LU request is high.
2.Call setup Indication is Low,which means there is either Imm. assignment reject(SDCCH Blk) or call setup indication timed out(T3101 expiry).
3.Your immediate aasignment success is poor for Non-call type.
1.Give tilt to the cell if overshooting
2.Check Co-BSIC-BCCH cells,if nearby
3.Increase Cell reselection hysteresis if on LA boundary.
4.Check for SDCCH Blocking(remote possibility)
This formula is actually too gross,you should use CSSR for CS services only.
You can increase the “RACH Min. Access level”,”RACH Busy threshold”,& “RACH error threshold” to reduce this,but you cant eliminate the effect totally.
It is better if you use “Immediate assignment commands/Immediate Assignment requests” in place of RA303I.