Headway switching, rather than feedforward loss alone, destabilises cooperative platoons under V2X dropout

This is the authors' abstract. We don't add key points for this paper.

Cooperative Adaptive Cruise Control (CACC) uses vehicle-to-everything (V2X) communication to sustain short, string-stable headways, but real wireless links drop packets, eroding this guarantee. We show that at a representative moderate-loss point, discontinuous headway switching on packet loss, not feedforward loss itself, is the dominant destabilising mechanism: a canonical plant-inverting design remains string stable losing feedforward at fixed headway, but not when switching headway on loss. Continuous, non-learned scheduling recovers stability at moderate but not severe loss. We train a dropout-aware multi-agent reinforcement-learning (TD3) controller with a learned V2X reliability gate; four of five training seeds converge to a policy string stable at $$30%$$ and $$60%$$ loss, outperforming the strongest classical scheduler under V2X-only information. The comparison is not information-matched: the learned policy also observes an idealised, always-exact onboard predecessor acceleration no classical controller here uses, and a non-learned controller given that signal alone is competitive with it, limiting attribution to learning. Frequency sensitivity, severe-burst robustness, and training reliability are all seed-dependent. These results identify switching, not information loss, as a primary vulnerability of communication-dependent platooning, and give a candid account of how much a learning-based remedy owes to learning itself.