Hello guys, some suggestions:
Due to traffic there are many options available, i.e. Directed Re-try, load based HO, relax compress mode and IRAT triggering threshold etc.
Further idle mode parameters can be tuned on 3G & 2G side.
You can also play with parameters like FDDQMIN and QSEARCH (I, C, P). These are the Idle mode regulation parameters which can be set from the 2G side. By tuning of this parameters you can make reselection procedure from 2G to 3G more complicated. So they can help you to keep more traffic at the 2G side.
But also check if in your network MS can go from 2G to 3G only by resection or also by handover (parameters - BET3GHOEN, OutSysLoadHoEn).
To shift traffic just during specific hours then load based handover is fine. OR you may schedule script in OSS for auto revision just mention specific time.
From 3G side you can also push more traffic to 2G by changing the IDLE mode parameters (Qqualmin, Qrxlevmin, SsearchRat, be careful - do not create ping pong). As other option to be more aggressive in IRAT HO thresholds from 3G to 2G - groups UCELLINTERRATHOCOV and UCELLINTERRATHONCOV). There are also load balancing algorithms for the traffic redistribution - check LDR and DRD if you 3G network has high traffic load that can help.
You can play with LDR actions in 3G to offload to 2G. LDR has 5 steps to offload the 3G traffic… CS INTERFREQ, PS INTERFREQ, CS IRAT, and PS IRAT.
LDR is more safe as a technique to offload the traffic since it will check the 2G condition before shifting the bearer.
And finally, in case you want the opposite, take a look here: Best way to move traffic from 2G->3G
Hope that helps.