thanks pix! your inputs are greatly appreciated.. i will review the parameters. maybe you have more to add with this clearer scenario.
the scenario is that,in a 200 meter tunnel. the car is moving very fast and cell-1 serving. at the middle of the tunnel, there is low rx lev (-90 to 100 dBm) already, quality is 7. there should be HO to cell-3 because that is the best neighbor but the result is call drop. however when we move slow, HO is executed successfully.
can i use parameters in fast moving HO even if they are in the same layer?