Hierarchical Dynamic Spectrum Sharing Between Terrestrial Networks and Non-Terrestrial Networks

Abstract

Integrated satellite-terrestrial networks (ISTNs) are envisioned as a key architecture for realizing ubiquitous coverage and efficient spectrum utilization in future communication systems. However, spectrum sharing between terrestrial networks (TNs) and non-terrestrial networks (NTNs) within ISTNs inevitably introduces cross-tier interference, which can degrade communication quality. To address this challenge, we introduce a hierarchical dynamic spectrum-sharing mechanism between TNs and NTNs to enhance spectrum utilization efficiency while maintaining the quality-of-service (QoS) requirements of TN and NTN users. We establish a generalized ISTNs framework comprising multiple satellites and terrestrial base stations (BSs), where TNs dynamically share a portion of their licensed spectrum with NTNs in remote areas. A Stackelberg game-theoretic framework is developed to capture the hierarchical interaction between TNs and NTNs. In this framework, terrestrial BSs act as leaders who jointly optimize their transmit power and spectrum-sharing time allocation to manage interference and incentivize cooperation. In response, satellites adjust their transmit power and spectrum access strategies to align with TN decisions. Utility functions for both TNs and NTNs are carefully designed to incorporate data-rate utility, energy consumption, and spectrum-access cost, balancing performance and resource efficiency. Simulation results demonstrate that even under imperfect channel state information (CSI), the introduced mechanism significantly improves overall utility, with gains of up to 18.3% for NTNs and 21.9% for TNs, while ensuring QoS requirements and accounting for the effect of spectrum utilization on mutual interference.