With the rapid development of high speed public
transportation, more travelers choose high speed
vehicles, such as bullet trains, for leisure or business
purpose. On-board passengers would like to
keep contact with the outside world through
mobile communications. On the other hand, the
service quality on high speed vehicles is far from
satisfactory. First, due to the Doppler effect at
high speed, channel condition becomes much
worse, which leads to the data rate degradation
and even radio link failure. Second, a large
group of UEs perform HO (Handover) simultaneously,
resulting in much reduced HO success
rate because of signaling congestion. Lastly, the
continuous measurements in both active and idle
mode can quickly draw out the UE power.