Optimal Energy-Saving Multi-Path Routing for Space-Air-Ground Integrated Networks

Traditional multi-path routing schemes for Space-Air-Ground Integrated Networks (SAGINs) pose the prominent challenge in reducing energy consumption. To address this, we study the energy minimization problem in multi-path routing by jointly optimizing link assignment, storage allocation, power control, and network routing in SAGINs over dynamic topologies. We first propose a Two-scale Time-Expanded Graph (TTEG) model to capture both network topology changes in large-timescale slots and mission data transmission in small-timescale slots. Using this TTEG model, we formulate the studied problem into a Mixed-Integer Non-Linear Program (MINLP) to minimize total energy consumption. We then leverage the inherent structure of the MINLP to divide it into two smaller subproblems. These two subproblems are solved iteratively with information feedback between them, thereby determining an optimal solution to the original problem in a few iteration steps. Simulation results validate the correctness and efficiency of the proposed solution.