Distributed IoT With LEO Satellites: Optimal Attempt Rate Schemes With Low Feedback

Abstract

Low Earth Orbit (LEO) nano-satellite communications are playing an increasingly vital role in supporting ground-based Internet of Things (IoT) sensing applications. A key challenge is designing grant-free uplink communication access schemes that are fair and scalable, with minimal feedback to the ground terminals. This paper proposes a novel weighted attempt rate (WAR) scheme. We formulate an ordinary differential equation (ODE) to find the optimal set of terminal weights that achieve max–min fairness. The ODE’s convergence to an optimal point is rigorously analyzed, and an ODE solver is developed. We also address the feedback overhead problem for dynamic IoT applications where terminal weights need to be changed on a per satellite pass basis. We propose a quantized time-grid clustering method with a corresponding feedback mechanism, which delivers the weights to terminals in real-time during the satellite pass. The number of weights depends only on the time-grid dimensions, thus ensuring that downlink signalling is independent of the terminal population size. Extensive numerical studies validate the convergence, robustness, and reliability of the proposed scheme, while also illustrating the inherent trade-off between feedback overhead and fairness performance.