Dynamic Routing for Integrated Satellite-Terrestrial Networks: A Constrained Multi-Agent Reinforcement Learning Approach

The integrated satellite-terrestrial network (ISTN) system has experienced significant growth, offering seamless communication services in remote areas with limited terrestrial infrastructure. However, designing a routing scheme for ISTN is exceedingly difficult, primarily due to the heightened complexity resulting from the inclusion of additional ground stations, along with the requirement to satisfy various constraints related to satellite service quality. To address these challenges, we study packet routing with ground stations and satellites working jointly to transmit packets, while prioritizing fast communication and meeting energy efficiency and packet loss requirements. Specifically, we formulate the problem of packet routing with constraints as a max-min problem using the Lagrange method. Then we propose a novel constrained Multi-Agent reinforcement learning (MARL) dynamic routing algorithm named CMADR, which efficiently balances objective improvement and constraint satisfaction during the updating of policy and Lagrange multipliers. Finally, we conduct extensive experiments and an ablation study using the OneWeb and Telesat mega-constellations. Results demonstrate that CMADR reduces the packet delay by a minimum of 21% and 15%, while meeting stringent energy consumption and packet loss rate constraints, outperforming several baseline algorithms.

I. Introduction

The popularity of LEO satellites is driven by their capability to provide wide-area coverage and high-speed internet communication services, delivering fast and reliable data transmission and communication capabilities to users, particularly in remote areas with limited infrastructure. Telesat [1] is a satellite communication project with a long-term strategy of deploying 351 satellites operating in the Ka-band at an altitude of approximately 1015 kilometers. Another typical example, OneWeb [2] plans to deploy around 720 satellites, enabling a vast satellite network that offers users worldwide reliable and low-latency internet connectivity, delivering high-speed broadband internet services.