RRU Calibration Topology for Minimizing Multi-Hop Deviation

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Solution Overview

Problem

Conventional calibration methods for remote radio units (RRUs) in communication systems suffer from calibration deviations due to multi-hop calibration paths, leading to reduced precision and poor signal quality, especially in scenarios requiring coherent multipoint joint transmission.

Innovation Solution

A calibration method that determines a calibration path topology with direct connections between RRUs having sufficient signal quality, allocates time-frequency resources for calibration signals, and calculates calibration coefficients based on path information to minimize hop count and reduce calibration deviations, thereby improving precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional calibration method with multi-hop calibration paths is used, then calibration can be performed across all RRUs, but calibration deviation accumulates and precision decreases

Engineering Contradiction:
Improvecalibration precisionVSAvoidcalibration deviation
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent segments the calibration process into direct pairs of RRUs, avoiding multi-hop paths. Each RRU is calibrated directly against reference RRUs through direct connections, dividing the calibration graph into independent direct pairs rather than allowing cumulative error propagation through multiple hops.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces reference RRUs as intermediary elements that provide stable calibration references. By establishing direct calibration paths from each RRU to reference RRUs, the system uses these reference points as mediators to eliminate cumulative errors that would otherwise propagate through multi-hop paths.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the number of calibration paths is increased to cover all RRUs, then coverage is improved, but calibration deviation accumulates and precision decreases

Engineering Contradiction:
Improvecalibration coverageVSAvoidcalibration precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the calibration network into direct pairs connected to reference RRUs. Instead of creating a single long multi-hop path covering all RRUs, the system divides coverage into multiple independent direct calibration pairs, each maintaining high precision while collectively providing comprehensive coverage.

Inventive Principle:
Principle #1Segmentation

3Area of stationary object

If RRUs are connected through multiple hops to establish calibration paths, then network coverage is extended, but calibration deviation accumulates

Engineering Contradiction:
Improvecalibration network coverageVSAvoidcalibration deviation
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent segments the calibration network into multiple direct calibration pairs, each with its own direct connection to reference RRUs. This segmentation allows the network to extend coverage through multiple reference points while maintaining direct (one-hop) calibration paths, preventing deviation accumulation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses reference RRUs as intermediary calibration anchors distributed throughout the network. Each RRU connects directly to these reference intermediaries, allowing extensive network coverage while maintaining stable, direct calibration paths that do not accumulate deviation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3706336B1Correction method and apparatus
Publication Date: 2023.01.04 HUAWEI TECH CO LTD
  • EP3706336B1 patent drawingFigure 1
  • EP3706336B1 patent drawingFigure 2A
  • EP3706336B1 patent drawingFigure 2B

AI summary

This application provides a calibration method and an apparatus, and relates to the field of communications technologies, to reduce a calibration deviation between RRUs and improve calibration precision. The method includes: receiving, by a control apparatus of an RRU, resource configuration information sent by a centralized control apparatus, where a time-frequency resource indicated by the resource configuration information is used to send and receive a calibration signal between the RRU and n other RRUs, the n other RRUs are RRUs in a calibration path topology, a quantity of hops of a calibration path between the RRU and each of the n other RRUs is 1, and a quantity of hops of a shortest calibration path between any two RRUs in the calibration path topology is less than or equal to a hop quantity threshold; controlling, based on the resource configuration information, the RRU to send and receive a calibration signal on the time-frequency resource; obtaining m groups of path information based on the calibration signal sent and received by the RRU; obtaining m calibration coefficients based on the m groups of path information; and compensating M channels of the RRU by using the m calibration coefficients.