Implementation of fast handovers and additional authentication in GSM/UMTS for high-speed users

We analyze how to speed-up handover in GSM and UMTS. There are several reasons to speed up handovers. On one hand these systems face problems with high-speed users, e.g. those moving in a high-speed train. This is important because the European railway organization decided to use GSM as their communication system for signaling and train control. As GSM was designed for speed up to 250 km/h there are problems with handovers and cell camping for higher speed. As the passengers in the train are going to communicate via UMTS the handovers of UMTS have also to be speed up. On the other hand it is known that there are security problems in GSM authentication that also weaken UMTS when having handovers between both systems. Therefore it is proposed to have an additional authentication just before the handover from UMTS to GSM. We analyzed how and how much time can be saved and show that we can also make use of the network topology to integrate additional authentication to secure the communication for example between the dispatcher and the train