  To attain seamless handover and reduce the han- dover failure probability for
high-speed railway (HSR) com- munication systems, this paper proposes a remote
antenna unit (RAU) selection assisted handover scheme where two antennas are
installed on high speed train (HST) and distributed antenna system (DAS) cell
architecture on ground is adopted. The RAU selection is used to provide high
quality received signals for trains moving in DAS cells and the two HST
antennas are employed on trains to realize seamless handover. Moreover, to
efficiently evaluate the system performance, a new met- ric termed as handover
occurrence probability is defined for describing the relation between handover
occurrence position and handover failure probability. We then analyze the
received signal strength, the handover trigger probability, the handover
occurrence probability, the handover failure probability and the communication
interruption probability. Numerical results are provided to compare our
proposed scheme with the current existing ones. It is shown that our proposed
scheme achieves better performances in terms of handover failure probability
and communication interruption probability.
