Time-Scale-Adaptable Spectrum Sharing for Hybrid Satellite-Terrestrial Networks

TL;DR

This paper tackles spectrum scarcity in hybrid satellite-terrestrial networks by introducing a time-scale-adaptable spectrum sharing framework that operates under coarse network-wide synchronization with time scale $\Delta\tau$ and relies on statistical CSI. It combines joint link scheduling and power control, satellite selection, and flexible frequency reuse, implemented via a low-complexity scheme based on link-feature sketching, hierarchical link clustering, Monte-Carlo sampling, and successive-approximation. The approach decouples scheduling and power optimization to reduce complexity while preserving performance, and it is shown to provide substantial throughput gains under strict interference constraints, with QoS guarantees for both CUs and SUs. The results suggest practical viability for scalable spectrum sharing in 6G-era hybrid networks, enabling efficient use of time-frequency resources with reduced signaling and coordination overhead.

Abstract

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.

Figures (14)

• Figure 1: Illustration of a hybrid satellite-terrestrial network.
• Figure 2: A random topology of the hybrid network for simulations.
• Figure 3: Average sum rate of the hybrid network for $F=4$.
• Figure 4: Average sum rate of the CUs achieved by different schemes for $F=4$.
• Figure 5: Proportion of SUs with QoS violation for $F=4$.