Proof of Concept: Local TX Real-Time Phase Calibration in MIMO Systems

Fuente: arXiv
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Main Authors: Collmann, Carl, Nimr, Ahmad, Fettweis, Gerhard
Format: Preprint
Published: 2026
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author Collmann, Carl
Nimr, Ahmad
Fettweis, Gerhard
author_facet Collmann, Carl
Nimr, Ahmad
Fettweis, Gerhard
contents Channel measurements in MIMO systems hinge on precise synchronization. While methods for time and frequency synchronization are well established, maintaining real-time phase coherence remains an open requirement for many MIMO systems. Phase coherence in MIMO systems is crucial for beamforming in digital arrays and enables precise parameter estimates such as Angle-of-Arrival/Departure. This work presents and validates a simple local real-time phase calibration method for a digital array. We compare two different approaches, instantaneous and smoothed calibration, to determine the optimal interval between synchronization procedures. To quantitatively assess calibration performance, we use two metrics: the average beamforming power loss and the RMS cycle-to-cycle jitter. Our results indicate that both approaches for phase calibration are effective and yield RMS of jitter in the 2.1 ps to 124 fs range for different SDR models. This level of precision enables coherent transmission on commonly available SDR platforms, allowing investigation on advanced MIMO techniques and transmit beamforming in practical testbeds.
format Preprint
id arxiv_https___arxiv_org_abs_2602_16441
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Proof of Concept: Local TX Real-Time Phase Calibration in MIMO Systems
Collmann, Carl
Nimr, Ahmad
Fettweis, Gerhard
Signal Processing
Channel measurements in MIMO systems hinge on precise synchronization. While methods for time and frequency synchronization are well established, maintaining real-time phase coherence remains an open requirement for many MIMO systems. Phase coherence in MIMO systems is crucial for beamforming in digital arrays and enables precise parameter estimates such as Angle-of-Arrival/Departure. This work presents and validates a simple local real-time phase calibration method for a digital array. We compare two different approaches, instantaneous and smoothed calibration, to determine the optimal interval between synchronization procedures. To quantitatively assess calibration performance, we use two metrics: the average beamforming power loss and the RMS cycle-to-cycle jitter. Our results indicate that both approaches for phase calibration are effective and yield RMS of jitter in the 2.1 ps to 124 fs range for different SDR models. This level of precision enables coherent transmission on commonly available SDR platforms, allowing investigation on advanced MIMO techniques and transmit beamforming in practical testbeds.
title Proof of Concept: Local TX Real-Time Phase Calibration in MIMO Systems
topic Signal Processing
url https://arxiv.org/abs/2602.16441