MADRL-based UAVs Trajectory Design with Anti-Collision Mechanism in Vehicular Networks
This addresses safety and efficiency challenges in UAV trajectory design for 6G vehicular networks, representing an incremental improvement over existing methods.
The paper tackles the problem of designing collision-free trajectories for multiple UAVs serving vehicular networks using multi-agent deep reinforcement learning, proposing a rank-based binary masking approach that reduces unsafe actions and improves training performance.
In upcoming 6G networks, unmanned aerial vehicles (UAVs) are expected to play a fundamental role by acting as mobile base stations, particularly for demanding vehicle-to-everything (V2X) applications. In this scenario, one of the most challenging problems is the design of trajectories for multiple UAVs, cooperatively serving the same area. Such joint trajectory design can be performed using multi-agent deep reinforcement learning (MADRL) algorithms, but ensuring collision-free paths among UAVs becomes a critical challenge. Traditional methods involve imposing high penalties during training to discourage unsafe conditions, but these can be proven to be ineffective, whereas binary masks can be used to restrict unsafe actions, but naively applying them to all agents can lead to suboptimal solutions and inefficiencies. To address these issues, we propose a rank-based binary masking approach. Higher-ranked UAVs move optimally, while lower-ranked UAVs use this information to define improved binary masks, reducing the number of unsafe actions. This approach allows to obtain a good trade-off between exploration and exploitation, resulting in enhanced training performance, while maintaining safety constraints.