Problem
Research questions and friction points this paper is trying to address.
Energy Efficiency
Load Balancing
Power Control
Satellite-Cell-Free Massive MIMO
User Association
Joint Load Balancing and Transmit Power Control for Energy Efficiency Maximization in the Satellite-Cell-Free Massive MIMO Uplink
🤖 AI Summary
This study addresses energy efficiency maximization in satellite–terrestrial integrated cell-free massive MIMO uplink systems under imperfect channel state information and practical user association constraints. By leveraging a spatially correlated Rician fading channel model, the authors derive a closed-form expression for the uplink ergodic throughput and formulate a joint user association and transmit power optimization problem. To efficiently solve this NP-hard problem within polynomial time, they propose an enhanced differential evolution algorithm. This work presents the first joint optimization framework for user association and power control in satellite–cell-free MIMO architectures, revealing the critical impact of association strategies on spectral efficiency and rate fairness. Simulation results validate the theoretical analysis and demonstrate that the proposed scheme significantly improves both network energy efficiency and throughput, while offering a scalable association criterion suitable for large-scale deployment.
📝 Abstract
The seamless integration of non-terrestrial and terrestrial infrastructures is a key enabler for ubiquitous connectivity in next-generation (NG) wireless networks. We investigate a hybrid satellite-cell-free Massive MIMO system, where multiple low-Earth-orbit (LEO) satellites jointly serve users in unison with terrestrial access points (APs) under realistic imperfect channel state information and practical user association constraints. We first derive closed-form expressions of the uplink ergodic throughput by exploiting maximum ratio combining (MRC) for transmission over spatially correlated Rician fading channels. Our analysis reveals the characteristic impact of both user-satellite and user-AP association patterns on both the spectral efficiency and rate-fairness achieved. We then formulate an energy efficiency optimization problem under joint user association and power control. Since the problems are inherently NP-hard due to the binary nature of the user-association variables, we develop an improved Differential Evolution (IDE) framework that efficiently explores the feasible solutions in polynomial time. Numerical results validate our analysis and show that the proposed hybrid scheme substantially improves energy efficiency and network throughput. For large-scale scenarios, the DE framework provides practical user-satellite-AP association guidelines, enabling scalable performance gains.
Innovation
Methods, ideas, or system contributions that make the work stand out.
Satellite-Cell-Free Massive MIMO
Energy Efficiency Maximization
Joint User Association and Power Control
Imperfect CSI
Improved Differential Evolution
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