HO Parameters in dual band Cells

Hi all,
We are implementing 850MHz cells in existing 1900MHz-Cells (Nokia), but without common BCCH feature. For a propagation reason, 850MHz cells get most traffic than the 1900 (using dual-band antennas)… Any advice about parameteres for traffic balancing between cells, without reducing TxPwr ? .. We have change PWRBGT_margins and active DADL direct_acces_to_desired_layer),

BR.