Control-Aware Energy-Efficient Transmission for Satellite Internet of Things Systems

As a promising solution for global coverage, low-earth orbit (LEO) satellite communication networks can provide reliable communication and stable control for Internet of Things (IoT) mobile devices. Compared to terrestrial networks, the limited transmission resources, extended propagation delay, and severe signal loss in satellite systems make it challenging to achieve energy-efficient wireless control for satellite IoT applications. In this article, we consider a satellite-based wireless control system (WCS) and propose a control-aware energy-efficient transmission scheme. Different from traditional satellite communication, this scheme ensures the control stability of the satellite IoT systems and minimize the transmission energy consumption through the joint design of satellite beamforming, power allocation, and user scheduling. To reduce energy consumption while satisfying control stability, we first transform the constraint of the control stability into a communication reliability requirement. Then, we use a Lyapunov drift-plus-penalty optimization framework to convert the long-term resource allocation into a deterministic one-shot problem. Finally, we solve the transformed problem through alternating optimization in each time slot. Specifically, user scheduling scheme is designed by utilizing a semidefinite relaxation approach and beamforming and power allocation are carried out by applying a path-following approach. Simulation results illustrate that the proposed schemes can achieve control stability of satellite IoT systems and obtain the lower energy consumption compared to existing schemes.