Cooperation between satellite and terrestrial wireless networks promises great potential in meeting fast-growing demands for ubiquitous communications coverage. To tackle spectrum scarcity, spectrum sharing is studied for a hybrid satellite-terrestrial network where satellite links share the same group of time-slotted sub-carriers with terrestrial links opportunistically. In particular, with coarse network-wide time synchronization, a time-scale-adaptable spectrum sharing framework is proposed based on a satellite-terrestrial cooperation time scale that can be flexibly adjusted according to practical requirements. For generality, it is assumed that both full and partial frequency reuse could be adopted among the base stations (BSs) and satellite selection is supported when multiple satellites are available. Relying on only statistical channel state information (CSI), joint link scheduling and power control are explored to maximize the average sum rate of the network while ensuring quality of service (QoS) for users. To solve the complicated mixed integer programming (MIP) problem, a low-complexity spectrum sharing scheme is presented based on link-feature-sketching-aided hierarchical link clustering and Monte-Carlo-and-successive-approximation-aided transmit power optimization. Simulation results demonstrate that by link feature sketching, diversity of the links brought by the spatial distribution of the users could be well utilized. The proposed scheme promises a significant performance gain even under strict inter-link interference constraints.

翻译：卫星与地面无线网络的协同为满足日益增长的泛在通信覆盖需求展现出巨大潜力。为解决频谱稀缺问题，本文研究一种混合星地网络的频谱共享机制，其中卫星链路与地面链路机会式共享同一组时隙化子载波。特别地，在粗粒度全网时间同步条件下，提出一种基于星地协同时间尺度的时域自适应频谱共享框架，该时间尺度可根据实际需求灵活调整。为保持普适性，假设基站间可采用全频复用或部分频复用策略，并在多卫星可用时支持卫星选择机制。基于统计信道状态信息，通过联合链路调度与功率控制，在保障用户服务质量的前提下最大化网络平均总速率。针对这一复杂的混合整数规划问题，提出一种低复杂度频谱共享方案，其核心包括基于链路特征素描的层次化链路聚类，以及基于蒙特卡洛与逐次逼近的发射功率优化。仿真结果表明，通过链路特征素描技术，可充分利用用户空间分布带来的链路分集增益。所提方案即使在严格的链路间干扰约束下，仍能实现显著的性能提升。