Terminal Uplink Control for Multi-TRP Cell Coordination

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Solution Overview

Problem

In future radio communication systems, controlling uplink transmission for multiple transmission/reception points or non-serving cells is challenging, leading to potential degradation of communication quality.

Innovation Solution

A terminal equipped with a receiving section to process downlink control channel orders and a control section to determine candidate cells based on these orders, enabling appropriate communication with multiple transmission/reception points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UL transmission control is performed for each transmission/reception point or cell, then communication quality can be maintained, but the complexity of control increases significantly

Engineering Contradiction:
Improvecommunication qualityVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the control approach by introducing a serving cell concept that coordinates multiple transmission/reception points. Instead of independently controlling each TRP, the system divides control responsibilities: the serving cell manages timing advance and random access procedures, while other TRPs are controlled through the serving cell's coordination. This segmentation reduces overall control complexity while maintaining communication quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The serving cell acts as an intermediary between the terminal and multiple transmission/reception points. The terminal controls UL transmission to the serving cell, which then coordinates with other TRPs. This intermediary approach simplifies terminal control logic while enabling quality maintenance across multiple points through centralized coordination at the serving cell level.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple transmission/reception points are used for communication, then communication capacity and reliability improve, but the difficulty of controlling uplink transmission increases

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidcontrol difficulty
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent merges control functions for multiple TRPs into a unified serving cell control mechanism. The terminal maintains a single timing advance value and performs random access procedures with the serving cell, which then coordinates UL transmission to all TRPs. This merging approach maintains communication reliability through multiple TRPs while reducing control difficulty by consolidating management functions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The serving cell is designed with multi-functionality, serving both as a regular communication point and as a coordinator for multiple other TRPs. It performs dual roles: receiving UL transmission from the terminal and managing timing/coordination for other TRPs. This universal approach enables reliable multi-TRP communication without increasing terminal control complexity.

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

3Measurement precision

If timing advance control is performed for each cell, then uplink synchronization is improved, but the number of control parameters increases

Engineering Contradiction:
Improveuplink synchronization precisionVSAvoidnumber of control parameters
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts timing advance control from individual TRP management and consolidates it at the serving cell level. Instead of maintaining separate timing advance parameters for each TRP, the system uses a single timing advance value managed by the serving cell. This extraction approach maintains uplink synchronization precision while reducing the number of control parameters the terminal must manage.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The serving cell performs preliminary timing advance determination through random access procedures, establishing a baseline timing value before actual UL transmission to multiple TRPs begins. This preliminary action at the serving cell enables subsequent TRP communications to use the established timing reference, avoiding the need for separate timing negotiations with each TRP and reducing overall control parameters.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4615133A1Terminal, wireless communication method, and base station
Publication Date: 2025.09.10 NTT DOCOMO INC
  • EP4615133A1 patent drawingFigure 1A~1D
  • EP4615133A1 patent drawingFigure 2A~2B
  • EP4615133A1 patent drawingFigure 3A~3B

AI summary

A terminal according to one aspect of the present disclosure includes: a receiving section that receives, from a candidate cell, a downlink control channel order to be used for triggering a random access procedure; and a control section that determines the candidate cell associated with a serving cell, based on the downlink control channel order. According to one aspect of the present disclosure, even when communication is performed by using a plurality of transmission points, communication can be appropriately controlled.