Remote Antenna Unit Selection Assisted Seamless Handover for High-Speed Railway Communications with Distributed Antennas

To attain seamless handover and reduce the handover failure probability for high-speed railway (HSR) systems, this paper proposed a remote antenna unit (RAU) selection assisted handover scheme based on two HST antennas and distributed antenna system (DAS) cell architecture. The RAU selection is adopted to provide high quality received signals for trains 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 metric termed as handover occurrence probability is define for describing the relation between handover occurrence position and handover failure probability. We derive the expressions of the received signal strength, the handover trigger probability, the handover occurrence probability, the handover failure probability and the communication interruption probability of our proposed method. Numerical experimental results are provided to compare our proposed scheme with traditional handover scheme and some existing ones. It is shown that, our proposed scheme is able to achieve the lowest handover failure probability and communication interruption probability among all schemes.