The only answear for WHY is because it’s NOKIA 🙂
Actualy MQL is in % from TCH resource on cell. For example if there are 3 TRX on the cell, so it’s about 24 TS, so MQL will be 12.
We changed parameters to 25%,5s,3s and SDCCH drop decreased were observed and HO sucsess rate increased!
Next step is to make TLH=0
Will see 😉