I think it might be more difficult than it would seem... everything I’ve seen so far in telecom has the assumption that the gNB (the base station) has a fixed location relative to neighboring gNBs. That’s what would facilitate handoffs. You would have to reconfigure parts of the core network as the train moves, so that you could smoothly handle the instance where someone takes a call on the train, disembarks, and the train pulls away. I don’t think the topology is that malleable.