Dynamic FDD for Spectrum Sharing in Non-Terrestrial Networks

2026-06-03

AI Summary

This work addresses the severe interference caused by densely deployed low Earth orbit (LEO) satellite constellations operating in shared frequency bands, a challenge that conventional fixed-frequency-division duplexing (FDD) systems struggle to mitigate due to their spectral rigidity. To overcome this limitation, the paper introduces, for the first time, a dynamic FDD mechanism tailored for non-terrestrial networks. The proposed approach enables interference-aware, flexible spectrum management through the joint optimization of dynamic bandwidth allocation, user scheduling, and bidirectional power control. The resulting non-convex mixed-integer problem is efficiently solved via equivalent transformation and alternating optimization, leveraging industrial-grade solvers. Experimental results demonstrate that, in dense deployment scenarios, the proposed scheme achieves up to a 30% improvement in system throughput compared to traditional FDD.

Abstract

Future 6G networks are envisioned to integrate low Earth orbit satellite mega-constellations to enable seamless global connectivity, particularly in underserved and remote areas. However, the deployment of dense mega-constellations introduces interference among satellites operating over shared frequency bands. This represents a rather new setup for studying spectrum sharing, which exacerbates the limited flexibility of conventional FDD systems based on fixed bands for downlink and uplink transmissions. We address this spectrum-sharing problem and propose dynamic re-assignment of FDD bands for improved interference management in dense deployments, as well as evaluate the performance gain of this approach. To this end, we formulate a joint optimization problem that incorporates dynamic band assignment, user scheduling, and power allocation in both directions. This non-convex mixed integer problem is solved using a combination of equivalence transforms, alternating optimization, and state-of-the-art industrial-grade mixed integer solvers. Numerical results demonstrate that the proposed approach of dynamic FDD band assignment significantly enhances system performance over conventional FDD, achieving up to 30\% improvement in throughput in dense deployments.

Problem

• spectrum sharing
• non-terrestrial networks
• interference management
• FDD
• satellite mega-constellations

Innovation

• Dynamic FDD
• spectrum sharing
• non-terrestrial networks
• interference management
• joint optimization