Dual-Tier IRS-Assisted Mid-Band 6G Mobile Networks: Robust Beamforming and User Association

TL;DR

This paper introduces a dual-tier IRS framework with terrestrial and aerial IRSs for 6G mid-band networks, enhancing connectivity and resource allocation in challenging environments, especially for IoT applications.

Contribution

It proposes a novel IRS-assisted framework combining terrestrial and aerial IRSs for 6G, addressing LoS blockages in the FR3 spectrum with an efficient joint beamforming and user association solution.

Findings

Approaches exhaustive search performance with lower complexity

Outperforms existing greedy and random baselines

Supports massive IoT connectivity in challenging environments

Abstract

The rapid growth of Internet of Things (IoT) applications necessitates robust resource allocation in future sixth-generation (6G) networks, particularly at the upper mid-band (7-15 GHz, FR3). This paper presents a novel intelligent reconfigurable surface (IRS)-assisted framework combining terrestrial IRS (TIRS) and aerial IRS (AIRS) mounted on low-altitude platform stations, to ensure reliable connectivity under severe line-of-sight (LoS) blockages. Distinguishing itself from prior work restricted to terrestrial IRS and mmWave and THz bands, this work targets the FR3 spectrum, the so-called Golden Band for 6G. The joint beamforming and user association (JBUA) problem is formulated as a mixed-integer nonlinear program (MINLP), solved through problem decomposition, zero-forcing beamforming, and a stable matching algorithm. Comprehensive simulations show our method approaches exhaustive search performance with significantly lower complexity, outperforming existing greedy and random baselines. These results provide a scalable blueprint for real-world 6G deployments, supporting massive IoT connectivity in challenging environments.