PUCCH Cell Selection in Dual-Connectivity Base Stations

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Solution Overview

Problem

In dual connectivity scenarios, there is a lack of a detailed method for the secondary eNB to determine which cell a terminal should transmit a Physical Uplink Control Channel (PUCCH) to, with the secondary eNB needing assistance from the master eNB but no clear method established on how to do so.

Innovation Solution

The master eNB generates assistance information based on radio quality measurements from the terminal, including cell identification and quality, which is then used by the secondary eNB to select the primary SCell (pSCell) for PUCCH transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the secondary eNB determines the PUCCH transmission cell autonomously, then the system complexity is reduced, but the communication quality and reliability deteriorate due to lack of coordination with master eNB

Engineering Contradiction:
Improvesystem complexityVSAvoidcommunication quality
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The master eNB acts as an intermediary by generating assistance information that guides the secondary eNB's cell selection for PUCCH transmission. This mediator approach allows the secondary eNB to make informed decisions without full autonomous authority, balancing system complexity with communication quality through coordinated information exchange.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the master eNB provides detailed assistance information to the secondary eNB, then the cell selection accuracy improves, but the information exchange overhead and processing complexity increase

Engineering Contradiction:
Improvecell selection accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The master eNB performs preliminary actions by pre-calculating and providing assistance information about suitable cells for PUCCH transmission before the secondary eNB needs to make its selection. This advance preparation enables the secondary eNB to make accurate cell selections without performing complex real-time analysis, thus improving selection accuracy while managing processing complexity.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If multiple cells are configured for PUCCH transmission, then the adaptability and coverage are improved, but the terminal's uplink control signaling complexity increases

Engineering Contradiction:
ImprovecoverageVSAvoidterminal signaling complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The PUCCH transmission functionality is segmented across multiple cells, with each cell configured for specific transmission purposes. The master eNB and secondary eNB divide the responsibility of PUCCH management, allowing the terminal to transmit control signals to multiple cells without bearing the full complexity of managing all transmission parameters centrally.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4084394B1Base station apparatus, control method, and program
Publication Date: 2025.11.19 KDDI CORP
  • EP4084394B1 patent drawingFigure 1~2
  • EP4084394B1 patent drawingFigure 3
  • EP4084394B1 patent drawingFigure 4~5

AI summary

In a wireless communication system in which when connecting one terminal apparatus to a base station apparatus and another base station apparatus, the other base station apparatus selects a frequency band to be used for control channels transmitted from the terminal apparatus to the other base station apparatus from a plurality of frequency bands usable by the other base station apparatus, and notifies the terminal apparatus of the selected frequency band, the base station apparatus acquires, from the terminal apparatus, information about radio quality of a signal received from the other base station apparatus for at least one frequency band out of the plurality of frequency bands, extracts portion of frequency bands out of the plurality of frequency bands based on the acquired information about radio quality, and notifies the other base station apparatus of information representing the portion of frequency bands.