TRP Selection Using CTDSIF to Limit CSI Aging in CJT

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Solution Overview

Problem

The selection of unsuitable candidate TRPs in coherent joint transmission (CJT) leads to rapid changes in the equivalent channel, making it highly sensitive to CSI aging, which significantly degrades CJT performance.

Innovation Solution

A method and device for selecting a TRP based on a channel time-domain selectivity increasement factor (CTDSIF) and a threshold, considering factors like Doppler shift, time intervals, and load, to determine suitable candidate TRPs for joint transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If unsuitable candidate TRPs are selected for coherent joint transmission, then the number of TRPs for joint transmission is increased, but the equivalent channel changes rapidly making it highly sensitive to CSI aging

Engineering Contradiction:
Improvenumber of TRPsVSAvoidCSI aging sensitivity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a new parameter CTDSIF (Channel Time-Domain Selectivity Increasement Factor) to quantify the time-domain selectivity change of the equivalent channel when adding candidate TRPs. By calculating and comparing CTDSIF values against thresholds, the system dynamically selects TRPs that minimize channel variability, thereby reducing CSI aging sensitivity while maintaining multi-TRP transmission benefits

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the UE measures the CTDSIF of the equivalent channel formed by serving TRP and candidate TRP, reports this information to the network device, and the network device uses this feedback to make informed decisions about TRP selection for coherent joint transmission, ensuring optimal channel stability

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If more candidate TRPs are selected to join serving TRP for CJT transmission, then transmission diversity is improved, but the equivalent channel becomes more sensitive to CSI aging

Engineering Contradiction:
Improvetransmission diversityVSAvoidCSI aging sensitivity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses CTDSIF as a key parameter to evaluate and compare different TRP combination scenarios. By calculating the CTDSIF for each candidate TRP combination and selecting combinations with lower values, the system achieves transmission diversity through multiple TRPs while maintaining channel stability and reducing CSI aging sensitivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic TRP selection based on real-time channel conditions. The CTDSIF calculation and comparison process allows the system to adaptively adjust which TRPs are selected for coherent joint transmission, optimizing the balance between transmission diversity and channel stability according to current environmental conditions

Inventive Principle:
Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Reduces CSI aging by selecting appropriate TRPs for joint transmission, enhancing CJT performance by considering time-domain changes in the equivalent channel.

Implementation Method 1

the first CTDSIF is determined based on a Doppler-domain bandwidth increasement factor or a normalized Doppler offset factor; wherein the Doppler-domain bandwidth increasement factor is determined based on a first bandwidth and a second bandwidth, the first bandwidth is determined by a Doppler-domain bandwidth of a composite channel

Methodology Applied
Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentEP4712652A1TRP selection method and apparatus, and communication device, communication system and storage medium
Publication Date: 2026.03.18 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4712652A1 patent drawingFigure 1~3
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  • EP4712652A1 patent drawingFigure 7~9

AI summary

Provided in the embodiments of the present disclosure are a TRP selection method and apparatus, and communication device, a communication system and a storage medium. The TRP selection method is executed by a UE, and comprises: determining a first CTDSIF of at least one first TRP, wherein the first CTDSIF is a CTDSIF of a first channel, which is a channel from the first TRP to the UE; acquiring a first threshold, wherein the first threshold is used for indicating a threshold of the CTDSIF; and on the basis of the first CTDSIF and the first threshold, determining whether to select the first TRP as a third TRP.