CSSR Optimization for GSM and WCDMA

CSSR stands for Call Set up Success Rate  that is one of important KPI(Key Performances Indicator) in Optimization both GSM and UMTS/WCDMA. For the beginning we have to know that KPI in WCDMA including CSSR are separated based on each Services such as : CSSR CS( for Voice services), CSSR PS(for PS/Data Services), CSSR Video(for Video Services),CSSR HSDPA(For HSDPA Services), CSSR HSUPA(for HSUPA Services). In GSM there is only one type CSSR(Voice Services), For Data services usually called as PDASR(Packet data Access Success Rate) or TBF Establishment Success Rate.There are some tips how to optimizes CSSR in GSM and WCDMA.
1. GSM CSSR Optimization tips 
-Make Sure no Hardware issue
Hardware checking is always the first step to check all KPI because you will have no impact about your action if common problem like Hardware or Installation has occurred in your network. Defect GRFU/CU(TRX Module) or Combiner will make CSSR degraded below 95%. Swap module to other sector to identify the problem and replace bad module.Also make sure no problem with Power or Transmission. Check for TCH availability and active alarm to make sure no hardware issue.
-Make Sure no SD Blocking
Lack of SDCCH can make degradation in CSSR because SD Blocking included in CSSR Formula, make sure no SD Blocking found in your cells. If found then you have to add SD channel based on Erlang Calculation. If you lazy to calculate, just add 1 channel first :D ,then increase 1 channel again if still found Blocking on SDCCH.
-Make Sure no Frequency Interference
Frequency Interference can make high SD drop in your cells.SD drop also included in CSSR Formula,check for SD drop first if found then you need to clear the cells by re-tune/change BCCH Frequency. Interference problem also will impact to other KPI like drop call rate, Handover, etc
-Make Sure no Overshooting
Overshooting also will make your CSSR getting low and under threshold because to much attempt at the edge of Coverage with low RX Level. You have to make sure no overshooting occurred to make good CSSR. If found then you need to adjust your coverage by add Tilting value(Down Tilt)
-Tuning Parameter
You need to change parameter smoothly if all main problem have cleared. Try to change wisely related access parameter such as : RXLEVAMI/RXLEVACCMIN/AccMin(Different name between Vendor),RACHBT,T200,MAXRETR,etc.Make sure no extreme setting to avoid bad user perception :D.
-TRX Layering
Shifting traffic from bad TRX  to Good TRX can improve your KPI included CSSR. Try to set Good TRX as high priority  and bad TRX as lowest priority to improve your CSSR. TRX BCCH usually has better Quality to set as highest priority because Full Power(No Power Control).

2. WCDMA CSSR Optimization Tips
Continued here

You might also Need to know:
- How to Optimize Handover Success Rate in GSM Network
- Drop Call Rate Optimization in GSM and UMTS
- Power Control activation for Electricity Saving in Huawei GSM