How to balance traffic 850 1900 3g

Hello,

Can you help me please, how can we balance traffic between 850 and 1900 in 3g, vendor NSN.

We use the same antenna, and the same azimuth. I tried before placing more tilt for 850 and less for 1900 like in gsm but i need parameters to force the traffic to 1900, as it is in GSM with (AUCL, C2, etc…). I dont know how can I do that in 3g.

Thank you for you help.