Dynamic Data Routing for Non-ISL LEO Satellite-Based NT-IoT Communications

Satellite-based IoT systems using Low Earth Orbit (LEO) constellations offer global coverage for delay-sensitive applications in remote regions. However, in non-inter-satellite link (non-ISL) constellations, intermittent visibility and missing ISLs pose major challenges for dynamic routing. In this letter, we investigate the routing problem of connecting remote IoT nodes to ground stations via visibility-limited satellites. We formulate a time-to-visibility matrix that captures link availability across all ground-satellite pairs and enables delay-aware routing. Building on this, we propose DyDRA, a Dynamic Dijkstra-based Routing Algorithm that exploits this matrix to construct low-latency paths in real time. DyDRA is lightweight and suitable for edge IoT devices with limited processing capabilities. Our simulations show that the proposed algorithm effectively minimizes routing delay, while offering significant processing time reduction, i.e., by more than 60% compared to other heuristic algorithms.