Ok, i gave you “design” values 🙂 To have a rough idea of your operator coverage, you can use any value you want… even though -106dBm seems to low. A MS shall be sensitive down to -102dBm. Not less than this.
So the minimal threshold you can use is -102dBm. But if anyone goes out and check the validity of your study, you’ll be in trouble 🙂 Also, in your RNP, did you set your tool to take into account body margin, fast fading and lognormal margin ?
For me, a “safe” threshold (for your purpose) would be -92dBm, for outdoor coverage.
A little aggressive would be -95dBm. And if noone is never going to check it, or if you want to compare your network with another operator that is using a certain threshold, then -of course- use their threshold !
If they already use -106dBm, then use -106dBm. Otherwise your network will look bad.