Radio Unit Tx-Rx Calibration Monitoring for Precoding Accuracy

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Solution Overview

Problem

Existing wireless radio communication systems face performance degradation due to suboptimal precoding matrices resulting from inaccurate transmitter-receiver (Tx-Rx) calibration in radio units, which is often undetected and difficult to correct, especially in time division duplexing (TDD) networks.

Innovation Solution

A software-based method for monitoring and correcting Tx-Rx calibration inaccuracies in radio units by exploiting channel reciprocity, using user equipment (UE) reports to adjust precoding matrices without additional hardware, and applying calibration phasors to recalibrate the Tx-Rx phase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a limited codebook of precoding matrices is used to reduce control signaling, then signaling overhead is reduced, but the selected precoding matrices become suboptimal

Engineering Contradiction:

Improvecontrol signaling overheadVSAvoidprecoding matrix optimality

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The system implements a feedback mechanism where the UE reports calibration status information about its Tx-Rx calibration. The base station uses this feedback to identify when recalibration is needed and to select appropriate precoding matrices based on actual calibration conditions, thereby maintaining optimality without increasing signaling overhead

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the precoding matrix selection based on calibration parameter changes. When calibration drift is detected, the system transitions from using fixed codebook entries to dynamically computing precoding matrices based on current channel state information and calibration status, resolving the contradiction between limited signaling and optimal performance

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If Tx-Rx calibration is performed initially, then beamforming and precoding can be established, but calibration inaccuracies occur over time due to heating, aging, and mechanical damage

Engineering Contradiction:

Improveinitial calibration setupVSAvoidcalibration accuracy over time

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The system performs preliminary calibration setup during manufacturing or initial deployment, establishing baseline Tx-Rx calibration. The calibration status information is then continuously monitored and updated, allowing the system to maintain accuracy despite aging and environmental factors by applying corrections based on detected drift

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE continuously reports calibration status information to the base station, providing feedback about calibration degradation. This enables the system to detect when calibration has drifted due to heating, aging, or mechanical damage and to apply corrections, thereby maintaining reliability over time without requiring continuous manual recalibration

Inventive Principle:

Principle #23Feedback

3Reliability

If calibration monitoring and correction is implemented, then communication performance is improved, but system complexity increases

Engineering Contradiction:

Improvecommunication performanceVSAvoidcalibration monitoring system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements self-service calibration monitoring where the UE autonomously reports its own calibration status information. The base station automatically processes this information and adjusts precoding matrices as needed, eliminating the need for complex external monitoring equipment or manual intervention while maintaining high communication performance

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The calibration status information reporting mechanism serves multiple functions: it monitors calibration accuracy, triggers recalibration when needed, provides data for precoding matrix selection, and enables performance optimization. This multi-functionality reduces overall system complexity by consolidating multiple monitoring and control functions into a single mechanism

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250323694A1Distributed unit monitoring and correction of a radio unit's transmitter-receiver calibration

Publication Date: 2025.10.16 DELL PROD LP

AI summary

The technology described herein is directed towards monitoring transmitter and receiver phase calibration by measuring phase calibration inaccuracies in a deployed and running base station, without utilizing any additional hardware or additional signaling. A group of reported user equipment precoding matrix indicators (PMIs) corresponding to each antenna of a radio unit of the base station is obtained and combined (e.g., averaged) into a user equipment-based PMI. A sounding reference signal (SRS)-based PMI is estimated at the base station based on user equipment sounding reference signal data received via the antenna. Receive and transmit phase difference data is determined for each antenna based on its corresponding user equipment-based PMI and the SRS-based PMI. Action can be taken on the phase difference, including to determine phase difference calibration coefficient data that is applied to compensate for the receive and transmit phase difference data, and/or report the difference data to an operator.