對比於現有的第三代行動電話技術(Universal Mobile Telecommunications System; UMTS)，長期演進技術 (Long-Term Evolution; LTE) 更能提供使用者在高鐵上快速而優良的連線品質，為國際鐵路聯盟(International Union of Railways; UIC)建議為下一代鐵路專用通訊標準。然而，在高達時速三百公里的移動過程中，接近基地台邊緣會有嚴重的訊號強度不足現象造成連線中斷、甚至造成換手失敗的情形。在高速的移動下，因為沿線經過的基地台多且須頻繁的轉換，因此若無有效的換手過程，很可能造成使用者斷斷續續的連線情形、甚至行動通訊裝置在重覆搜索基地台訊號的情況下，電池蓄電量將大幅耗損。
為了解決上述問題，本論文提出以移動式中繼站技術來提供使用者不需換手的通訊品質。使用架設於車廂中的移動式中繼站提供穩定的訊號給使用者，以架設於列車頂的天線來與外界大型基地台做通訊連結，更按照列車固定行進與速度的模式，提出中繼站內建基地台白名單、主動換手、複製並提早傳送封包至沿線基地台的換手方式，來提高換手的準確性和成功率。從模擬結果可得知，本論文提出的方法不僅排除乒乓效應的發生機率，達成最精簡的換手次數，換手失敗率也減少19%，在高速下發生信號品質不良的RLF機率也減少20%。

In contrast to the existing third-generation mobile phone technology (Universal Mobile Telecommunications System, UMTS), Long Term Evolution (Long-Term Evolution, LTE) provides users excellent communication quality on the high-speed rail. LTE also has been proposed as next generation railway communication standards by the International Union of Railways. However, in the course of up to 300 kmph, close to the edge of the base station, there might be serious signal weak lead to connection interruption, even handover failure. Moreover, due to the frequently base station change, there might be bad connection experience, cause depletion of battery capacity under repeatedly searching signal without effective handover procedure.
To solve issues mention above, we propose a new technology applying relaying to provide users handover-less communication by setting up a relay node inside the train to provide stable quality signal strength to users and connecting to base station by antenna set up on the top of train. Then we propose a novel handover scheme to rise up handover success rate with white list, active handover and bi-casting according to the features of fixed direction and speed of train. Simulation results show that the proposed scheme can not only avoid ping-pong handover, but also reduce 19% handover failure rate and 20% RLF.

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