I am not familiar with ZTE but I am quiet confused with your last Scenario:
“Maxpathloss:-132 and Min Pathloss: 126 and Max1800 TA:1 and Min1800 TA:0. After that 90% traffic in 1800 and again 90% calls on 900 and making congestion.”
Is this correct? how can you have 90% of Traffic on 1800 and the congestion is on the 900?