No such parameter exist within Alcatel & Ericsson. Not explicitly .
What i’ll suggest to you is to upgrade your 1800 band to 4 TRX. Then make this band as the prefered band for traffic what i mean is to put more load on this band. Then do drive test from near the cell till the village to see if sufficient level is received from 1800 band, if not normally a handover from 1800 to 900 band will be done.
If the level (1800 band) in the village is sufficient enough then you could downgrade the 900 band in order to have this configuration 2 TRX in 900 band and 4 TRX in 1800 band.
The reason why to do this is that 1800 band suffer more from path loss than 900 band.