Create a network with two base stations connected to an MSC
Let BS1 be at (1000,1000) and the BS2 be at (2000,1000) and the network grid be 5000 * 5000
Keep MS1 at 500,1000 and set mobility to zero
Keep MS2 at 1500, 1000 (mid way between two BS) and set mobility to say 100 m per s
Generate traffic from MS1 to MS2.
Call Inter arrival time = 1s
Call duration = 1000 s
Run simulation for say 250 seconds
Check packet animation you are likely to see the mobile undergoing hand over between the two BS's.
Also, in the performance metrics, under the cellular metrics you will find Handover Requests that were send by each Mobile Station(MS).
Open the packet trace and you will see that hand over request packets will be shown at this time.
Note: In GSM hand over is based on distance (hard hand over), while in LTE it is based on SNR (soft hand over)