AoI-Aware Energy Efficiency Resource Allocation for Integrated Satellite-Terrestrial IoT Networks

Integrated satellite and terrestrial network (ISTN) is a potential technology to achieve ubiquitous and reliable broadband communication for Internet of Things (IoT) devices. Timely delivery of information updates represents a pivotal metric in IoT networks. However, due to the limited satellite transmission resources and the huge propagation delay caused by long distance from satellites to the Earth, ISTN faces great challenges in ensuring such freshness. Moreover, energy efficiency (EE) is also a crucial factor in ISTN with multiple antennas serving multiple users. In this research, we incorporate Age of Information (AoI) as a metric to ensure the information freshness of all IoT devices and design an AoI-aware EE resource allocation scheme. We maximize the system average EE by jointly optimizing the beamforming of Low Earth Orbit (LEO) satellites and base station (BS), and scheduling while maintaining the maximum AoI constraints of all IoT devices. To solve such a difficult problem, a Lyapunov drift-plus-penalty approach is leveraged to transform the original dynamic resource allocation problem into a deterministic problem, which is efficiently solved by an alternating optimization. Compared with existing schemes, our proposed scheme achieves the highest average EE. Our simulations also verify the tradeoff between average EE and information freshness.