Accelerated Graph Neural Networks on an SoC FPGA for Onboard LEO Satellite Network Routing

This paper presents a system-on-chip field-programmable gate array (SoC FPGA) acceleration architecture for graph-neural-network- and deep-reinforcement-learning (GNN–DRL)-based routing inference in low-Earth-orbit (LEO) satellite networks. Because LEO satellites move at high orbital speeds, the network topology changes continuously, and routing decisions must track the current link state rather than rely only on static rules. GNN-based DRL routing can represent the graph structure of the network when selecting paths, but its message-passing and readout stages are computationally expensive for resource-constrained onboard platforms. To address this limitation, the trained GNN routing model is ported to an SoC FPGA and implemented with a collaborative processing-system (PS) and programmable-logic (PL) architecture. The PS handles candidate-path generation, environment setup, path selection, and network-state updates, whereas the PL executes the computationally dominant message-passing neural network (MPNN) and readout layers. Post-training INT8 quantization, nonlinear-function approximation, vector-level parallelization, and a parallel multiply–accumulate structure are applied to reduce memory pressure and execution time. Experiments on a ZCU104 board using a PYNQ-controlled PS–PL implementation and an NSFNET-based routing environment show that the proposed PS–PL structure reduces the evaluation time from 94.08 s to 12.63 s compared with the PS-only implementation while maintaining an evaluation score close to that of the original model.