Over-the-Air Phase Synchronization for CoMP Joint Transmission

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Solution Overview

Problem

Coordinated multipoint (CoMP) joint transmission in wireless communication networks is limited by phase synchronization issues, particularly due to phase drifts across base stations, which degrade performance and are not adequately addressed by existing calibration methods that are infrequent and inefficient.

Innovation Solution

Implementing over-the-air phase synchronization techniques that utilize reciprocity-based feedback mechanisms, such as UE-assisted operations and inter-gNB cooperation, to maintain accurate phase coherence among base stations during coordinated multipoint transmissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If infrequent calibration methods are used to maintain phase synchronization, then device complexity is reduced, but phase synchronization precision deteriorates due to phase drifts across base stations

Engineering Contradiction:
Improvecalibration mechanism complexityVSAvoidphase synchronization precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements continuous feedback mechanisms where base stations exchange phase information through uplink and downlink transmissions. User equipment (UE) assists by providing feedback on received phase information, enabling the system to detect and correct phase drifts in real-time without requiring complex infrequent calibration procedures.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system enables base stations to autonomously maintain phase synchronization through self-organizing mechanisms. Each base station continuously monitors its own phase coherence with other base stations and automatically adjusts its transmission phase based on received feedback, eliminating the need for external calibration intervention.

Inventive Principle:
Principle #25Self-service

2Reliability

If continuous phase synchronization is implemented, then phase coherence is maintained, but loss of time increases due to frequent calibration overhead

Engineering Contradiction:
Improvephase coherenceVSAvoidcalibration overhead time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Phase synchronization is maintained continuously through ongoing uplink and downlink transmissions rather than through periodic calibration interruptions. The useful communication action itself serves as the synchronization mechanism, eliminating dedicated calibration time slots while maintaining phase coherence throughout the transmission period.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The uplink and downlink transmission channels serve dual purposes: they simultaneously carry user data/communication traffic and phase synchronization information. This multi-functionality allows phase coherence to be maintained without requiring separate calibration procedures, thus avoiding time loss while ensuring reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If reciprocity-based feedback mechanisms are used, then phase synchronization accuracy is improved, but device complexity increases due to UE-assisted operations and inter-gNB cooperation

Engineering Contradiction:
Improvephase synchronization accuracyVSAvoidfeedback mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

User equipment (UE) acts as an intermediary that facilitates phase synchronization between base stations. The UE receives downlink transmissions from multiple base stations, measures phase differences, and provides feedback to the base stations. This intermediary approach enables accurate inter-gNB phase coordination without requiring direct complex communication infrastructure between base stations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4009599B1Over-the-air phase synchronization for reciprocity-based comp joint transmission
Publication Date: 2026.03.04 QUALCOMM INC
  • EP4009599B1 patent drawingFigure 1
  • EP4009599B1 patent drawingFigure 2
  • EP4009599B1 patent drawingFigure 3

AI summary

The invention relates to a receiving node for over-the-air phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission. A receiving node receives a first phase synchronization reference signal (PSRS) from a plurality of other network nodes in communication with the first network node, computes a co-phasing value based on a phase difference between the first PSRS of each pair of the plurality of other network nodes, and transmits a second PSRS to one or more of the plurality of other network nodes, wherein the second PSRS is modulated for transmission by the first network node using the co-phasing value.