FHAP: Fast Handover Authentication Protocol for High-Speed Mobile Terminals in 5G Satellite–Terrestrial-Integrated Networks

The integration of satellite and terrestrial networks presents new opportunities and challenges for high speed rail (HSR) communications. Since the HSR runs vary fast, user terminals on the HSR have to perform handover authentication when the HSR passes through different terrestrial base stations or satellite coverage areas. To improve the security and robustness of HSR communication services, a fast handover authentication protocol (FHAP) for high-speed mobile terminals in the 5G satellite–terrestrial-integrated networks (STNs) is proposed. In the FHAP, user terminals in the same carriage form a temporary group managed by a relay node. The prehandover authentication mechanism is employed, in which the terrestrial 5G core network configures the preauthentication information to multiple access nodes based on the Chinese Remainder Theorem according to the location information of the HSR. Thus, group members and one of the access nodes can achieve fast handover authentication with the preconfigured information. Considering that HSR has a high running speed, when handover authentication fails, user terminals can perform handover authentication with other access nodes, and the probability of handover authentication failure caused by a single access node can be effectively reduced. We use the protocol verification tool Scyther and the Burrows–Abadi–Needham (BAN) logic to prove the security of the FHAP and compare it with other similar protocols in terms of signaling, bandwidth, and computational overhead. The analysis results show that the FHAP satisfies better security properties and has excellent performance.