hi,
on 2G :
1/ decrease the fdd ecno and fdd rscp thresholds, so that the MS will reselect the 3G at lower levels.
2/ ensure all other idle parameters will ease the exit of 2G and reselection to 3G
on 3G :
1/ reduce the 2d threshold and increase the 2D time to trigger
2/ in idle, delay the the threshold to exit the 3G and reselect the 2G.
Regards