Multi-Aircraft Cooperative Handover Scheme for Satellite-to-Aircraft Communication Systems

In this work, we propose a multi-aircraft cooperative handover scheme for satellite-to-aircraft communication systems. Specifically, considering the dual characteristics of aircraft resource demands and three satellite states (normal, congested, and failed), multiple aircraft collaborate to make handover decisions while maintaining network stability and avoiding congestion. We formulate the cooperative handover problem as a multi-objective optimization problem to minimize communication latency and network congestion while maximizing connection stability. To solve this problem, we first model the handover scheme into the Markov decision process to facilitate seamless satellite-aircraft handover. Then we develop a multi-agent deep deterministic policy gradient (MADDPG) algorithm with centralized training and decentralized execution architecture. Due to the time-varying nature of the action space and the constraint that action selection is limited to currently visible and undamaged satellites, we implement an action mask approach to effectively filter out illegal actions instead of using conventional negative reward methods. The simulation results demonstrate that the proposed framework effectively reduces handover frequency, minimizes communication latency, and achieves better network load balancing, validating its feasibility and effectiveness in satellite-toaircraft communication systems.