Repeater-Aided Over-the-Air Phase Synchronization in Distributed MIMO

2026-03-20

AI Summary

This work addresses the challenge of phase synchronization in distributed MIMO systems, where weak or absent direct links between access points hinder coherent joint transmission. To overcome this limitation, the paper introduces a relay-assisted over-the-air phase calibration scheme—leveraging a relay node for the first time in this context—and proposes a closed-form calibration algorithm that achieves high-precision phase synchronization without requiring direct inter-access-point links. By enabling accurate synchronization even under severely limited interconnectivity, the proposed approach effectively resolves a critical bottleneck in practical deployments of distributed MIMO. Consequently, it significantly extends the operational applicability of such systems and preserves their performance advantages in challenging propagation environments.

Technology Category

• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs

Abstract

Phase synchronization of access points (APs) in a distributed multiple-input multiple-output (D-MIMO) system is critical to leverage the performance benefits of D-MIMO. Existing over-the-air phase synchronization methods assume that APs can communicate directly to perform necessary measurements. However, this assumption might not hold in scenarios where inter-AP signaling is too weak for effective communication. To address this, in this paper, we propose a novel over-the-air calibration scheme that uses repeater nodes to facilitate phase synchronization when direct AP signaling is infeasible. We give the steps of the algorithm for phase calibration in closed form, and show how it enables coherent joint transmission (CJT) by the APs. The framework expands the applicability of D-MIMO systems to challenging environments, where existing over-the-air synchronization techniques fall short.

Problem

• phase synchronization
• distributed MIMO
• over-the-air calibration
• repeater-aided
• coherent joint transmission

Innovation

• repeater-aided synchronization
• over-the-air calibration
• distributed MIMO
• coherent joint transmission
• phase synchronization