Energy Efficient Downlink mMIMO Using Dynamic Antenna and Power Adaptation

TL;DR

The paper tackles energy efficiency in downlink mMIMO for 6G by introducing a dynamic per-slot scheme that jointly adapts the number of active antennas and transmit power using a CSI-RS based antenna adaptation and the POLITE power adaptation method. It formulates a per-user, per-slot optimization that balances network energy savings (NES) with user perceived throughput (UPT), leveraging per-user buffers and channel measurements. The key contribution is the integration of antenna and power adaptation into a cohesive scheduling framework, demonstrated to significantly reduce energy consumption (approximately 35–41% gains under certain loads) while maintaining throughput across varying traffic conditions. This approach offers practical energy savings for large-scale mMIMO deployments, with future work focusing on mitigating CSI acquisition limitations of the multi-CSI-RS framework.

Abstract

Massive multiple-input multiple-output (mMIMO) technology and its future evolutions are expected to address the high data rate demands of sixth generation (6G) communication systems. At the same time, network energy savings (NES) is essential in reducing the operational costs and meeting the sustainability goals of network operators. In this regard, we propose a dynamic scheme for joint antenna and power adaptation to improve NES from a user scheduling and resource allocation perspective. Antenna adaptation is performed using the multiple channel state information resource signal (CSI-RS) framework. Furthermore, the recently introduced transmit power-aware link adaptation scheme, referred to as POLITE for short, is used as the power adaptation technique. The proposed scheme adapts to variations in users' instantaneous traffic and channel conditions to opportunistically maximize NES while also inherently accounting for the user throughput. Numerical simulation results show that the proposed scheme consistently achieves a balance between NES and user perceived throughput (UPT) for different network load conditions. Especially in low and light load conditions, the proposed scheme significantly improves the intra-cell interference and boosts the overall NES, while ensuring that UPT is unaffected.

Figures (5)

• Figure 1: Illustration of multiple CSI-RS framework
• Figure 2: Comparison of power consumption vs network load
• Figure 3: Comparison of user throughput vs network load
• Figure 4: Empirical distribution of interference power values
• Figure 5: Comparison of resource utilization vs network load