Distributed Spectrum Sharing in UAV-Assisted HetNet Considering Interference Coordination: A Two-Level Stackelberg Game Approach

To address the low efficiency of traditional spectrum-sharing systems, UAVs can serve as airborne relays to enhance user communication services. However, the issues of spectrum scarcity and underutilized spectrum holes have not been fully resolved. Therefore, designing an effective spectrum resource reallocation mechanism is essential to improve spectrum utilization efficiency further. Moreover, existing research rarely explores co-channel interference arising from spectrum trading between UAVs and often overlooks queuing mechanisms in spectrum trading scenarios. This paper proposes a dynamic spectrum-sharing scheme (DSS) leveraging UAV-assisted communication to address these challenges. To enhance spectrum utilization, a two-level Stackelberg game-based incentive mechanism is developed for on-demand UAV spectrum trading. Additionally, a co-channel interference preference-based spectrum matching scheme (CIPS) is designed, which comprehensively considers co-channel interference resulting from spectrum sharing and prioritizes the importance of UAV users’ services. Finally, optimal pricing and trading volume strategies are efficiently determined using a gradient-based iterative search algorithm. Simulation results demonstrate that the proposed model achieves higher system revenue, which is 8.97% to 186.82% higher than other models, and ensures flexible spectrum allocation and effective co-channel interference mitigation.