Thank you for your replay. 🙂
I’ve done the checks that you asked:
1. It’s CESTIMMASS(number of SDCCH establishment failure due to timeout after sending Immediate Assignment, timer T3101 expired.) that goes up when the SDCCH establishment succes rate goes down
2. The trafic is the same. No changes before/after the degradation
3. SDCCH_mht is also constant. No chagens before/after the degradation
4. I didn’t find nothing that could help me. I made the analysis on MO, MT, LU and SMS but nothing.
I also mention that i played a little with MAXTA and TA and i obtained great results: CESTIMMASS was reduced to low valeus and SDCCH_establishment_rate was good again.
But again, i don’t implement this solution because with the same values the performance was good.
I guess i have to go and ask for RACH traces.