以多重無線存取技術強化高速列車無線傳輸之研究

Abstract

在高速列車上提供商用行動通訊網路服務會面臨到一些挑戰，尤其當高速列車快速行經基地台的無線覆蓋區域時，頻繁的換手可能會造成嚴重的通訊中斷問題。解決方法如階層式兩層架構與無縫雙連線換手機制被提出來克服這些挑戰。本論文提出多重無線接取技術，即允許高速列車同時連上兩種以上的異質網路 (如通用行動通訊系統網路與長期演進技術網路)，來解決高速列車上網路換手問題。以此方法，便能夠藉由同時保持高速列車上的多重異質網路連線，以及在其它網路連結進行換手流程時於現有連結上維持網路連線，來改善換手流程。我們展現出多重無線接取技術可以藉由減少換手失敗的影響來有效強化高速列車上的通訊。本方法可與其他解決方案如雙連線換手機制並用以更加強化高速列車上的通訊效能。

Provisioning commercial mobile telecommunications service on high speed train (HST) faces several challenges. In particular, when a HST quickly passes through the radio coverage of the base stations, frequent handovers may result in serious communication interruption. Methods such as the hierarchical two-hop (HTH) network and the seamless dual-link handover scheme were proposed to address these challenges. This paper proposes the multiple radio access technology (multi-RAT) to resolve the HST handover issue, which allows the HST to simultaneously connect to two or more heterogeneous mobile networks (e.g., Universal Mobile Telecommunications System (UMTS) and Long Term Evolution (LTE)). With this approach, the handover process can be improved by keeping multiple heterogeneous network links of the HST at the same time and maintaining the connection through one link during the handover process of the other link. We show that multi-RAT can effectively enhance HST communications by reducing the impact of handover failure. This approach can work together with other solutions such as the dual-link scheme to further enhance the performance of the HST communications.