1/ Could you try to increase the Cell Reselect Hysteresis in both cells ? Also, increase the HO_Margin in both directions.
2/ Could you relocate (and add) the SDCCH timeslot onto other TRX’s ?
3/ Could you resize the size of the RSL on the Abis for the TRE that are carrying SDCCH timeslots ? I mean.. instead of multiplexing 4 RSL in 1 Abis TS, try to multiplex only 2 RSL / Abis TS.
Could you give me the RTCH_Assign_Fail_Radio_Rate and *_BSS_Rate and *_Cong_Rate ?
Do you see an increase in the amount of RTCH_Assign_Request ?