n a UMTS network, a mobile user is moving from one Node B to another within the same Radio Network Controller $($RNC$)$ area. The initial signal strength from Node B$1$ is $-75$ dBm$,$ and from Node B$2$ it is $-90$ dBm$.$ The user moves at a constant speed of $10$ m$/$s$,$ and the handover threshold is set at $-85$ dBm$.$ The distance between Node B$1$ and Node B$2$ is $2$ km$.$