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Abstract—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. Index Terms—handover, hierarchical two-hop (HTH), high speed train (HST), multiple radio access technology (Multi-RAT) I