Energy-and Spectral-Efficiency Trade-off in Distributed Massive-MIMO Networks

Abstract

This paper investigates the energy efficiency (EE) and spectral efficiency (SE) trade-off in uplink distributed massive multiple-input multiple-output (D-mMIMO) systems. Unlike conventional approaches where power consumption focuses primarily on transmit power, we use a comprehensive system-level power consumption framework which incorporates consumption due to fronthaul signaling, distributed processing, and circuit level power, which are, themselves, critically influenced by the dynamic access point (AP) activation (ON-/OFF decisions), and AP-user equipment (UE) association strategies. Consequently, we analyze the EE-SE trade-off through the joint optimization of transmit power allocation, AP activation, and AP-UE association. We formulate an optimization problem that maximizes EE while satisfying sum-SE constraints, per-user minimum SE requirements, and fronthaul capacity limits. Our solution uses a fractional programming-based approach to simultaneously determine transmit power levels, dynamic AP-UE associations, and AP activation strategies. Numerical results demonstrate that dynamic AP activation and association substantially impact the EE-SE trade-off, revealing optimal operating points that balance spectral performance with energy consumption. The findings provide practical guidelines for energyefficient D-mMIMO deployment in next generation wireless networks, highlighting the importance of adaptive resource allocation in achieving sustainable high-performance communications.