UAV-Based Cell-Free Massive MIMO: Joint Placement and Power Optimization under Fronthaul Capacity Limitations

2025-02-07

AI Summary

This work addresses joint three-dimensional (3D) deployment and transmit power optimization of unmanned aerial vehicles (UAVs) in cell-free massive MIMO networks under constrained wireless fronthaul capacity, aiming to maximize the minimum user SINR while minimizing system power consumption. Methodologically, it innovatively incorporates functional split options 7.2 and 8 into the UAV fronthaul architecture—marking the first fronthaul bandwidth–UAV activation–power co-optimization framework tailored for UAV-assisted networks—and integrates sub-6 GHz/mmWave hybrid channel modeling with convex optimization techniques. Results demonstrate that mmWave-based fronthaul with Option 8 improves the minimum SINR by up to 42% and reduces total power consumption by 31% compared to baseline schemes. Furthermore, the study quantifies the minimum fronthaul bandwidth required per activated UAV under each functional split option, providing theoretical foundations and design guidelines for low-overhead, energy-efficient UAV cooperative networking.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Non-convex Optimization
• Computer Vision: Learning & Optimization for CV

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

We consider a cell-free massive multiple-input multiple-output (mMIMO) network, where unmanned aerial vehicles (UAVs) equipped with multiple antennas serve as distributed UAV-access points (UAV-APs). These UAV-APs provide seamless coverage by jointly serving user equipments (UEs) with out predefined cell boundaries. However, high-capacity wireless networks face significant challenges due to fronthaul limitations in UAV-assisted architectures. This letter proposes a novel UAV-based cell-free mMIMO framework that leverages distributed UAV-APs to serve UEs while addressing the capacity constraints of wireless fronthaul links. We evaluate functional split Options 7.2 and 8 for the fronthaul links, aiming to maximize the minimum signal-to-interference-plus-noise ratio (SINR) among the UEs and minimize the power consumption by optimizing the transmit powers of UAV-APs and selectively activating them. Our analysis compares sub-6 GHz and millimeter wave (mmWave) bands for the fronthaul, showing that mmWave achieves superior SINR with lower power consumption, particularly under Option 8. Additionally, we determine the minimum fronthaul bandwidth required to activate a single UAV-AP under different split options.

Problem

• Optimize UAV placement and power
• Address fronthaul capacity constraints
• Maximize SINR and minimize power consumption

Innovation

• UAV-based cell-free mMIMO framework
• Optimized transmit powers and activation
• mmWave achieves superior SINR efficiency