Obstacle-Aware Multicast Routing Algorithm for Large-Scale LEO Constellations

The emergence of large-scale Low Earth Orbit (LEO) satellite networks presents new opportunities for high-quality video distribution. Leveraging advanced multicast technologies, LEO constellations can efficiently utilize satellite access and backbone network bandwidth, thereby reducing network traffic. However, existing research has predominantly focused on multicast within LEO constellations, overlooking the obstacle challenges introduced by satellite failures or link congestion in large-scale multilayer LEO networks. This paper proposes a novel approach to enhance the quality of satellite-based video distribution services in large-scale LEO satellite networks. Our method combines Software-Defined Multicast (SDM) and obstacle avoidance technologies. Firstly, we model obstacle links in LEO satellite networks. Building upon this, we design a multilayer obstacle avoidance spanning graph and validate the effectiveness of multilayer link replacement for optimizing tree length. Additionally, we develop a multilayer obstacle avoidance rectilinear Steiner tree construction algorithm that utilizes the multilayer obstacle avoidance spanning graph and multilayer link replacement. Through rigorous experimental evaluation, the algorithm presented in this study significantly mitigates link congestion within the LEO network. In comparison to conventional baseline algorithms, our algorithm demonstrates a 7% improvement in optimizing tree length, concurrently ensuring successful obstacle avoidance.